TWI383181B - Method for manufacturing a wide-frequency twisted layer liquid crystal film, a circularly polarizing plate, a linear polarizing element, a lighting device, and a liquid crystal display device (2) - Google Patents

Description

Method for manufacturing broadband twisted layer liquid crystal film, circular polarizing plate, linear polarizing element, illumination device and liquid crystal display device (2)

The present invention relates to a method of manufacturing a broadband twisted layer liquid crystal film. The wide-band torsion layer liquid crystal film of the present invention can be used as a circularly polarizing plate (reflective type polarizer). Moreover, the present invention relates to a linear polarizing element, an illumination device, and a liquid crystal display device using the circular polarizing plate.

In general, a liquid crystal display has a structure in which a liquid crystal is injected between glass plates forming a transparent electrode, and a polarizer is disposed in front of and behind the glass plate. The polarizer used in such a liquid crystal display is produced by absorbing iodine or a dichroic dye or the like on a polyvinyl alcohol film and extending it in a certain direction. The polarizer thus produced absorbs light that vibrates in one direction, and only passes light that vibrates in the other direction to generate linearly polarized light. Therefore, the efficiency of the photon cannot theoretically exceed 50%, which is the biggest cause of the decrease in the efficiency of the liquid crystal display. Moreover, since the light absorbing light causes the liquid crystal display device to increase the output of the light source to a certain extent, the polarized light is destroyed by the heat generated by the heat transfer of the absorbed light, and, due to the inside of the unit cell The thermal influence of the liquid crystal layer may result in poor display quality and the like.

The torsion layer liquid crystal having a circular polarization separation function is such that the rotation direction of the liquid crystal spiral coincides with the circular polarization direction, and has a selective reflection characteristic of reflecting only circularly polarized light having a wavelength of liquid crystal. By using this selective reflection characteristic, a specific circularly polarized light of natural light in a certain wavelength band is transmitted and separated, and the remaining light is reflected and reused, whereby a highly efficient polarizing film can be manufactured. At this time, the circularly polarized light that has passed through is converted into a linearly polarized light by the λ/4 wavelength plate, and the direction of the linearly polarized light is made The absorption direction of the absorption type polarizer used for the liquid crystal display is uniform, whereby a liquid crystal display device having high transmittance can be obtained. That is, once the twisted-layer liquid crystal film is combined with the λ/4 wavelength plate as a linear polarizing element, there is theoretically no loss of light, so that compared to the conventional absorption type polarizer that absorbs 50% of light alone, In theory, the brightness can be increased by 2 times.

However, the selective reflection characteristics of the twisted layer liquid crystal are limited to a specific wavelength band, and it is difficult to cover the entire visible light line. The thickness of the selected reflection wavelength domain of the torsion layer liquid crystal Δλ is: Δλ=2 λ‧(ne-no)/(ne+no)

No: refractive index of twisted layer liquid crystal molecules to normal light

Ne: refractive index of twisted liquid crystal molecules on abnormal light

λ: The center wavelength of the selective reflection is expressed by the molecular structure of the twisted layer liquid crystal. According to the above formula, if ne-no is made larger, the selective reflection wavelength domain width Δλ is widened, and ne-no is usually 0.3 or less. When this value is made large, other functions (orientation characteristics, liquid crystal temperature, and the like) of the liquid crystal may become insufficient, which is practically difficult. Therefore, in reality, the reflection wavelength domain width Δλ is also selected to be about 150 nm at the maximum. It can be used as a twisted layer liquid crystal only up to 30~100nm.

Also, the reflection center wavelength λ is selected to be: λ = (ne + no) P / 2

P: The pitch length required for the twisting of the twisted layer liquid crystal indicates that if the pitch is fixed, the average refractive index and the pitch of the liquid crystal molecules are long.

Therefore, to cover the entire field of visible light, it is possible to carry out a plurality of laminated layers having different selective reflection center wavelengths, or to continuously change the pitch in the thickness direction to form The existence distribution of the selective reflection center wavelength.

For example, a method of continuously changing the pitch length in the thickness direction can be referred to, for example, Japanese Laid-Open Patent Publication No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. In this method, when the torsion layer liquid crystal composition is cured by ultraviolet light, the exposure intensity difference between the exposure surface side and the emission surface side is imparted, and a difference in polymerization speed is imparted, thereby providing a liquid crystal composition having a different reaction rate in the thickness direction. The composition ratio changes.

The focus of this method is to increase the difference in exposure intensity between the side of the exposure surface and the side of the emission surface. Therefore, in many cases of the above-described embodiments of the prior art, a method in which an ultraviolet absorber is mixed with a liquid crystal composition to cause absorption in the thickness direction to increase the exposure amount with an optical path length is employed.

However, in the method of continuously changing the pitch length in Japanese Laid-Open Patent Publication No. Hei 6-281814, the thickness of the liquid crystal layer required for the function to be exhibited must be about 15 to 20 μm, and in addition to the precise coating problem of the liquid crystal layer, a large amount of high price is required. LCD, so the cost increase is inevitable. And the exposure time needs to be about 1~60 minutes. If you want to get the production line speed of 10m/min, the length of the exposure production line needs to be longer than the manufacturing line of 10~600m. If the line speed is reduced, the production line length can be reduced, but the production speed is reduced, but it is inevitable.

This is disclosed in Japanese Laid-Open Patent Publication No. Hei 6-281814, the composition of which is caused by the difference in the ultraviolet light exposure intensity in the thickness direction and the difference in the polymerization speed caused by the change in the pitch length in the thickness direction. Compared with the change, it is theoretically problematic to control the pitch of the torsion layer by the composition ratio change, so it is very difficult to form a rapid pitch change. In Japanese Laid-Open Patent Publication No. Hei 6-281814, the pitch length between the short pitch side and the long pitch side is about 100 nm, so the composition ratio must be changed greatly. To achieve this, it is necessary to have a comparable liquid crystal thickness, weak ultraviolet radiation, and extended exposure time.

In the publication of Japanese Laid-Open Patent Publication No. H11-248943, the material having a change in the pitch is superior to the material used in the Japanese Patent Publication No. Hei 6-281814. Therefore, the film can be formed in an exposure amount of about 1 minute. However, this situation still requires a thickness of 15 μm.

In the specification No. 3272668, the temperature conditions of the primary exposure and the double exposure are changed, and the time required for the composition ratio to vary in the thickness direction is additionally disposed in the dark, however, if the substantial visible light region is covered by the method, the temperature is The waiting time for the movement of the substance caused by the change takes about 120 minutes.

In the method of continuously changing the pitch length in the publication of JP-A-2002-286935, it takes about 15 to 20 μm for the function to exhibit the required liquid crystal layer thickness, and in addition to the precise coating problem of the liquid crystal layer, a large amount of expensive liquid crystal is required. Therefore, the increase in costs is inevitable. In the case where the torsion layer liquid crystal composition is cured by ultraviolet light exposure from the base material and the opposite side (air interface side), the exposure intensity difference between the exposure surface side and the emission surface side is given by oxygen inhibition. Thereby, the composition ratio change is changed in the thickness direction.

However, in the fourth embodiment of the first embodiment of the Japanese Patent Publication No. 2002-286935, although the selective reflection wavelength is widened, the inclination of the short-wavelength end side and the long-wavelength side of the transmittance curve is stable, substantially Not covered by the entire visible light range. Further, in the sixth embodiment of the second embodiment of the publication, the inclination of the two wavelength ends is steep, and the frequency band is narrow.

In particular, when such a polarizing element is used in a liquid crystal display device, it is necessary to sufficiently ensure a flat transmittance/reflectance characteristic for three wavelengths of 435 nm, 545 nm, and 615 nm of an emission spectrum of a backlight source. Noted in JP-A-2002-286935 The wide-bandwidth range obtained by the methods of Examples 1 and 2, each of which does not sufficiently cover the luminance spectrum of 435 nm and 615 nm. In this case, it is difficult to obtain white color by the light ray, and it cannot be used for a liquid crystal display device or the like.

In response to the above problems, the applicant has filed a special request No. 2001-339632. In this application, the liquid crystal composition coated on the oriented substrate is irradiated with ultraviolet rays from an oriented substrate. Thereby, the surface is polymerized from the surface of the liquid crystal layer, which is less susceptible to the influence of oxygen on the contact-oriented substrate, which is advantageous for the polymerization resistance, which facilitates the absorption of the molar extinction coefficient of the liquid crystal layer, and forms an ultraviolet irradiation intensity distribution in the thickness direction to reduce the air surface which is hindered by oxygen. The effective ultraviolet radiation amount on the side is formed to form a slope larger than the conventional liquid crystal reaction speed and a composition concentration distribution slope. By giving the difference in exposure intensity between the exposure surface side and the emission surface side as described above, it is possible to form a large change in the thickness direction of the twisted layer pitch length. In this application, it is possible to obtain a selective reflection wavelength bandwidth of up to 296 nm.

The aforementioned application may cover a wavelength band of about 400 to 700 nm. These wavelength bands cover the spectrum of the source. These provide good circularly polarized light reflection characteristics near normal incidence. On the other hand, when obliquely incident, a sufficient wavelength bandwidth cannot be said. The selected reflection wavelength λ due to oblique incidence is: λ = npcos{sin ^-1 (sin θ/n)}

n = average refractive index of liquid crystal

p=Twisted layer pitch length

θ = angle of incidence Once obliquely incident, the selected reflection wavelength will move to the shorter wavelength side than when it is incident vertically. Therefore, in order for oblique incident light to function effectively, it must be made to function in the long wavelength range.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method of fabricating a wide-band twisted layer liquid crystal film having a wide-band reflection band in a long wavelength region.

Further, an object of the present invention is to provide a circularly polarizing plate using a wide-frequency torsion layer liquid crystal film produced by the manufacturing method, and to provide a linear polarizing element, an illumination device, and a liquid crystal display device using the circular polarizing plate.

As a result of intensive studies to solve the above problems, the present inventors have found that a wide-frequency twisted-layer liquid crystal film which achieves the above object can be obtained by the following production method, and completed the present invention. That is, the present invention is as follows.

A method for producing a wide-band twisted layer liquid crystal film comprising the steps of applying a liquid crystal mixture containing a polymerizable liquid crystal precursor compound (A) and a polymerizable optically active agent (B) to an oriented substrate, and ultraviolet absorbing the liquid crystal mixture Irradiating the step of polymerizing and hardening to produce a wide-band twisted-layer liquid crystal film having a reflection bandwidth of 200 nm or more, wherein the ultraviolet polymerization step comprises: at a temperature of 20 ° C or higher in a state where the liquid crystal mixture is brought into contact with an oxygen-containing gas a step (1) of performing ultraviolet irradiation for 0.2 to 5 seconds from the side of the oriented substrate with ultraviolet irradiation intensity of 20 to 200 mW/cm ² ; and then, in a state where the liquid crystal layer is brought into contact with an oxygen-containing gas, at 70 Step (2) of heating at 120 ° C for 2 seconds or more; then, in a state where the liquid crystal layer is brought into contact with an oxygen-containing gas, at a temperature of 20 ° C or higher, lower than the ultraviolet irradiation intensity of the step (1), from the foregoing Step (3) of subjecting the substrate side to ultraviolet irradiation for 10 seconds or more; then, step (4) of irradiating ultraviolet rays in the absence of oxygen.

2. The method of producing a wide-band twisted layer liquid crystal film according to the above item 1, wherein the pitch length change of the wide-band twisted layer liquid crystal film is continuously narrowed from the side of the oriented substrate.

3. The method for producing a wide-band twisted layer liquid crystal film according to the above item 1, wherein the polymerizable liquid crystal original compound (A) has one polymerizable functional group, and the polymerizable optically active agent (B) has two or more. Polymeric functional group.

4. The method for producing a wide-band twisted layer liquid crystal film according to any one of items 1 to 3 above, wherein the molecular extinction coefficient of the polymerizable liquid crystal original compound (A) is 0.1 to 500 dm ³ mol ^-1 cm ^-1 @ 365 nm, 10 to 30000 dm ³ mol ^-1 cm ^-1 @334 nm, and 1000 to 100000 dm ³ mol ^-1 cm ^-1 @314 nm.

5. The method for producing a wide-band twisted layer liquid crystal film according to any one of items 1 to 4 above, wherein the polymerizable liquid crystal original compound (A) is represented by the following general formula (1):

a compound represented by the formula (wherein R ₁ to R ₁₂ may be the same or different and represent -F, -H, -CH ₃ , -C ₂ H ₅ or -OCH ₃ , and R ₁₃ represents -H or -CH ₃ , X ₁ represents a general formula (2): -(CH ₂ CH ₂ O) _a -(CH ₂ ) _b -(O) _c -, X ₂ represents -CN or -F, and only a in the general formula (2) is An integer from 0 to 3, b is an integer from 0 to 12, c is 0 or 1, and b=0, c=0 when a=1~3, b=1~12, c=0~ when a=0 1).

A circular polarizing plate using a wide-frequency twisted layer liquid crystal film obtained by the production method according to any one of the above items 1 to 5.

A polarizing element in which a front phase difference is arranged between at least two reflective polarizers (a) in which wavelength bands of selective polarization of polarization are overlapped with each other (normal line side) a phase difference layer (b) having a λ/8 or more with respect to incident light obliquely incident at 30° or more with respect to the normal direction, wherein the reflective polarizer (a) is a circle of the above-mentioned sixth item Polarizer.

8. The polarizing element according to item 7 above, wherein the selective reflection wavelength of the at least two reflective polarizers (a) overlaps each other in a wavelength range of 550 nm ± 10 nm.

9. The polarizing element according to Item 7 or 8, wherein the retardation layer (b) is a planar orientation for fixing a liquid crystal phase of a twisted layer having a selective reflection wavelength region outside the visible light region for fixing the rod shape. The vertical alignment state of the liquid crystal is used to fix the phase of the phase of the discotic liquid crystal or the orientation of the tube bundle phase, or to orient the polymer film 2 or to fix the inorganic lamellar compound having a negative 1 axis. , the normal direction of the face constitutes the optical axis.

A linear polarizing element which is obtained by laminating a λ/4 plate on the circular polarizing plate of the sixth item or the polarizing element of any one of the above items 7 to 9 to obtain a linear polarized light.

11. The linear polarizing element according to item 10 above, wherein the twisted layer liquid crystal film of the laminated circular polarizing plate is continuously narrowed to the λ/4 plate so that the pitch length is continuously narrowed.

12. The linear polarizing element according to the above item 10 or 11, wherein the λ/4 plate is subjected to phase difference correction of the 2-axis extended oblique incident light to improve the phase difference plate of the viewing angle.

13. The linear polarizing element according to the above item 10 or 11, wherein the λ/4 plate is coated and fixed with a nematic liquid crystal or a matrix liquid crystal, and the liquid crystal polymer type has a phase difference board.

The linear polarizing element according to any one of the items 10 to 13, wherein the λ/4 plate has a main refractive index of nx and ny in the in-plane, and a main refractive index in the thickness direction is nz. The Nz coefficient defined by nx-nz)/(nx-ny) satisfies -0.5 to -2.5.

A linear polarizing element which is obtained by laminating a λ/2 plate on a λ/4 plate of the linear polarizing element according to any one of the above items 10 to 14.

A linear polarizing element which aligns a transmission axis direction of an absorbing polarizer with a transmission axis of a linear polarization element according to any one of the above 10th to 15th, and laminates the absorption on a λ/4 plate side of the linear polarization element. Type photon.

A illuminating device comprising the circular polarizing plate of the sixth aspect, the polarizing element according to any one of the above items 7 to 9, or the 10th to 16th, on the surface side of the surface light source having the reflective layer on the back side A linear polarizing element of any one of the items.

A liquid crystal display device comprising a liquid crystal cell on a light emitting side of the illumination device of the above item 17.

A viewing angle-enhancing liquid crystal display device in which the viewing angle-enhancing film that diffuses light passing through a visual side of a liquid crystal cell is disposed on a visual side of a liquid crystal cell in the liquid crystal display device of the above-described item 18.

20. The liquid crystal display device of claim 19, wherein a diffusion plate having substantially no backscattering and polarization elimination is used as the viewing angle widening film.

As described above, in the present invention, in order to increase the reflection bandwidth, when the liquid crystal mixture is irradiated with ultraviolet rays from the side of the oriented substrate in contact with the oxygen-containing gas, the ultraviolet irradiation illuminance and the irradiation temperature are in the first exposure step. (1) In the step (3) of the second exposure, conditions different from each other are used. Thereby, the control of the reaction behavior of the polymerizable liquid crystal mixture can be made more compact, and a wide-frequency twisted layer liquid crystal film can be obtained by a high-efficiency production speed as compared with the prior art.

In other words, the ultraviolet irradiation conditions are the first irradiation intensity > the second irradiation intensity, and the first irradiation time < the second irradiation time. Further, a heating step (3) is provided between the first ultraviolet irradiation and the second ultraviolet irradiation. The amount of radicals generated by the ultraviolet light reaction of the photoreaction initiator in the liquid crystal composition per unit time varies greatly in the first ultraviolet irradiation and the second ultraviolet irradiation by the difference in irradiation intensity. In the first ultraviolet irradiation, a large amount of radicals are instantaneously formed in a monomer-rich condition at the initial stage of the reaction, and the absorption of the liquid crystal composition causes the radicals to be distributed to form a large inclination in the thickness direction. A polymer/oligomer having an average molecular weight of about 10,000 to 500,000 is formed thereby, and a concentration distribution is formed in the thickness direction. Moreover, in this case, since the reaction rate of the polymerizable liquid crystal raw compound (A) and the polymerizable optically active agent (B) in the liquid crystal mixture is different, the polymerization ratio is different in the thickness direction. Therefore, the polymerizable optical agent (B) has a short pitch in the rich surface and a long surface in the opposite direction. Thereby, a twisted layer liquid crystal film having a reflection wavelength of a wide frequency as a whole can be obtained.

The wide-frequency torsion layer liquid crystal film thus obtained can be used as a wide-band circularly polarizing reflector, and has the same optical properties as those of the above-mentioned Japanese Patent Publication No. Hei 6-281814, and the like, and the number of laminated sheets is reduced as compared with the conventional manufacturing method. It can reduce the thickness, and it can be easily manufactured in a short time, which can reduce the cost due to the increase in production speed.

The wide-band torsion layer liquid crystal film obtained by the above-described manufacturing method of the present invention has a reflection bandwidth of a selective reflection wavelength of 200 nm or more and a wide-band reflection bandwidth. The reflection bandwidth is preferably 300 nm or more, more preferably 400 nm or more, especially It is preferably at 450 nm. Further, the reflection bandwidth of 200 nm or more is preferably in the field of visible light, particularly in the wavelength range of 400 to 900 nm.

The circularly polarizing reflector also has a broadband reflection band in the long wavelength region, which is an important problem for the liquid crystal display device in order to obtain a good viewing angle. In the practical range of view, in order to make the transmitted light not visible, the long wavelength end of the selective reflection must reach 800 to 900 nm. According to the manufacturing method of the present invention, a wide-band twisted layer liquid crystal film having a reflection bandwidth at the long wavelength end can be obtained. The wide-frequency twisted-layer liquid crystal film is not only used as a polarizing element which is formed by a combination of other optical element groups such as a phase difference plate, but also when it is used as a reflective polarizer for obtaining high luminance. The oblique incident light has a stable optical characteristic.

Simple illustration

Fig. 1 is a conceptual diagram of an enlarged liquid crystal display device using the viewing angles of the polarizing plate-integrated polarizing elements of Examples 1 and 3 and Comparative Examples 1 to 3.

Fig. 2 is a conceptual view showing an enlarged liquid crystal display device by the viewing angle of the polarizing plate-integrated polarizing element of the second embodiment.

Fig. 3 is a view showing the axial angles of the respective layers in the polarizing plate-integrated polarizing element of the second embodiment.

Fig. 4 is a reflection spectrum of the twisted layer liquid crystal film produced in Example 1, Comparative Example 1, and Comparative Example 2.

The wide-frequency twisted-layer liquid crystal film of the present invention is obtained by subjecting a liquid crystal mixture containing a polymerizable liquid crystal original compound (A) and a polymerizable optical agent (B) to ultraviolet polymerization.

The polymerizable liquid crystal original compound (A) is suitably used to have at least one polymerization. A functional group having a liquid crystal original group formed of a cyclic unit or the like. The polymerizable functional group may, for example, be an acrylonitrile group, a methacryl group, an epoxy group or a vinyl ether group, and among them, an acrylonitrile group or a methacryl group is preferred. Moreover, by using a polymerizable functional group having two or more, a crosslinked structure can be introduced to improve durability. Examples of the cyclic unit to be a liquid crystal priming unit include biphenyl, phenyl benzoate, phenylcyclohexane, azobenzene, azomethine, azobenzene, and phenylpyrimidine. , diphenylacetylene, biphenyl benzoate, dicyclohexane, cyclohexylbenzene, terphenyl and the like. Further, the terminal of these cyclic units may have a substituent such as a cyano group, an alkyl group, an alkoxy group or a halogen group. The liquid crystal primor may also be bonded via a pitch plate portion that imparts flexibility. The pitch plate portion may be a polymethylene chain or a polyhydroxymethylene chain. The number of the structural units forming the pitch plate portion can be appropriately determined by the chemical structure of the liquid crystal original portion, and the reversal unit of the polymethylene chain is preferably 0 to 20, and preferably 2 to 12, and the polyhydroxymethylene chain. The reversal unit is preferably 0~10, and 1~3 is better.

The molar extinction coefficient of the polymerizable liquid crystal original compound (A) is 0.1 to 500 dm ³ mol ^-1 cm ^-1 @365 nm, 10 to 30000 dm ³ mol ^-1 cm ^-1 @334 nm, and 1000 to 100000 dm ³ mol ^-1 cm. ^-1 @314nm is better. Those having the aforementioned moir extinction coefficient have ultraviolet absorbing energy. The molar extinction coefficient is suitably 0.1 to 50 dm ³ mol ^-1 cm ^-1 @365 nm, 50 to 10000 dm ³ mol ^-1 cm ^-1 @334 nm, and 10000 to 50000 dm ³ mol ^-1 cm ^-1 @314 nm. The molar extinction coefficient is more suitably 0.1 to 10 dm ³ mol ^-1 cm ^-1 @365 nm, 1000 to 4000 dm ³ mol ^-1 cm ^-1 @334 nm, and 30,000 to 40000 dm ³ mol ^-1 cm ^-1 @314 nm. If the molar extinction coefficient is less than 0.1 dm ³ mol ^-1 cm ^-1 @365 nm, 10 dm ³ mol ^-1 cm ^-1 @334 nm, 1000 dm ³ mol ^-1 cm ^-1 @314 nm, sufficient polymerization speed difference cannot be given. It is difficult to widen. On the other hand, if it is more than 500 dm ³ mol ^-1 cm ^-1 @365 nm, 30000 dm ³ mol ^-1 cm ^-1 @334 nm, 100000 dm ³ mol ^-1 cm ^-1 @314 nm, the polymerization may not proceed completely, and hardening may not be completed. Further, the molar extinction coefficient is a value measured by measuring the spectrophotometry of each material from the extinction degrees of 365 nm, 334 nm, and 314 nm obtained.

The polymerizable liquid crystal original compound (A) having one polymerizable functional group may, for example, be of the following general formula: (1) a compound represented by the formula (wherein R ₁ to R ₁₂ may be the same or different and represent -F, -H, -CH ₃ , -C ₂ H ₅ or -OCH ₃ , and R ₁₃ represents -H or -CH ₃ , X ₁ represents a general formula (2): -(CH ₂ CH ₂ O) _a -(CH ₂ ) _b -(O) _c -, and X ₂ represents -CN or -F. However, a in the general formula (2) is An integer from 0 to 3, b is an integer from 0 to 12, c is 0 or 1, and b=0, c=0 when a=1~3, b=1~12, c=0~ when a=0 1).

Specific examples of the polymerizable liquid crystal original compound (A) represented by the general formula (1) are shown in Table 1.

The polymerizable liquid crystal original compound (A) is not limited to these exemplified compounds.

Further, the polymerizable optical agent (B) is, for example, LC756 manufactured by BASF Corporation.

The amount of the polymerizable optically active agent (B) is preferably 1 to 20 parts by weight, and 3 to 7 parts by weight, based on 100 parts by weight of the total of the polymerizable liquid crystal original compound (A) and the polymerizable optical agent (B). good. The helical twisting force (HTP) can be controlled by the ratio of the polymerizable liquid crystal original compound (A) to the polymerizable optically active agent (B). By With the foregoing ratio within the foregoing range, the reflection band can be selected such that the reflection spectrum of the obtained torsion layer liquid crystal film covers the long wavelength region.

Further, the liquid crystal mixture usually contains a photopolymerization initiator (C). The photopolymerization initiator (C) can be used in various kinds without particular limitation. For example, Irgacure Irgacure 184, Irgacure 907, Irgacure 369, Irgacure 651, etc., manufactured by Ciba Specialty Chemicals Co., Ltd. may be mentioned. The amount of the photopolymerization initiator is preferably from 0.01 to 10 parts by weight, more preferably from 0.05 to 5 parts by weight, per 100 parts by weight of the total of the polymerizable liquid crystal original compound (A) and the polymerizable optically active agent (B).

In the above mixture, in order to broaden the bandwidth of the obtained twisted layer liquid crystal film, an ultraviolet absorber may be mixed to increase the difference in ultraviolet exposure intensity in the thickness direction. Further, the same effect can be obtained by using a photoreaction initiator having a large molar extinction coefficient.

The foregoing mixture can be used as a solution. The solvent used in the preparation of the solution can usually be used: halogenated hydrocarbons such as chloroform, dichloromethane, dichloroethane, tetrachloroethane, trichloroethylene, tetrachloroethylene, chlorobenzene, phenol, p-chloro Phenols such as phenol, aromatic hydrocarbons such as benzene, toluene, xylene, methoxybenzene, 1,2-dimethoxybenzene, others such as acetone, methyl ethyl ketone, ethyl acetate, and third Alcohol, glycerol, ethylene glycol, triethylene glycol, ethylene glycol monomethyl ether, diethylene glycol dimethyl ether, ethyl sialoin, butyl cytosine, 2-pyrrolidone, N-methyl-2-pyrrolidone, pyridine, triethylamine, tetrahydrofuran, dimethylformamide, dimethylacetamide, dimethylhydrazine, acetonitrile, butyronitrile, carbon disulfide, cyclohexanone, Cyclopentanone and the like. The solvent to be used is not particularly limited, and methyl ethyl ketone, cyclohexanone, cyclopentanone or the like is preferred. The concentration of the solution is not limited to the thickness of the twisted-layer liquid crystal film due to the solubility to the thermal liquid crystalline compound or the final purpose, and is usually about 3 to 50% by weight.

The production of the wide-frequency twisted layer liquid crystal film of the present invention comprises the steps of applying the liquid crystal mixture to the oriented substrate, and polymerizing and curing the liquid crystal mixture by ultraviolet irradiation.

The oriented substrate may be any known ones, for example, a film formed of a polyimide film or a polyvinyl alcohol or the like formed on a substrate and rubbed with a rayon cloth or the like; A vapor-deposited film; a light-oriented film which irradiates a polarizing ultraviolet-ray on a polymer which has a photo-crosslinking group, such as cinnamic acid or azobenzene, or a polyimine In addition, it can also be oriented by magnetic field, electric field orientation, and friction stress operation.

The type of the substrate is not particularly limited, and a method of irradiating the irradiation line (ultraviolet rays) from the substrate side is preferable to use a material having a high transmittance. For example, the substrate preferably has a transmittance of 10% or more, particularly 20% or more, in an ultraviolet region of 200 nm or more and 400 nm or less, particularly 300 nm or more and 400 nm or less. Specifically, a plastic film having a transmittance of ultraviolet rays having a wavelength of 365 nm of 10% or more and even 20% or more is preferable. Further, the transmittance is a value measured by a U-4100 Spectrophotometer manufactured by HITACHI.

Further, as the substrate, polyethylene terephthalate, triacetonitrile cellulose, normethazine resin, polyvinyl alcohol, polyimine, polyallyl ester, polycarbonate, polyfluorene or polyether can be used. A film made of plastic, a glass plate, or a quartz sheet. For example, triacetyl cellulose manufactured by FUJIFILM Co., Ltd., ARTON manufactured by JSR, and ZEONEX manufactured by Japan ZEON can be mentioned.

Further, the polymer film described in JP-A-2001-343529 (WO01/37007) may, for example, contain a thermoplastic resin having a substituted and/or unsubstituted guanamine group in the side chain of (A), and (B) ) having substituted and/or unsubstituted benzene on the side chain A resin composition of a base and a nitrile-based thermoplastic resin. Specific examples thereof include a film comprising a cross-polymer of isobutylene and N-methylbutyleneimine and a resin composition of an acrylonitrile styrene copolymer. As the film, a film formed of a mixed product of a resin composition or the like can be used.

The substrate may be used in a state of being adhered to the twisted-layer liquid crystal layer, or may be removed by peeling. When used in a fitted state, a material having a very small phase difference in practical use is used.

When it is used for bonding to a substrate, it is preferable to use a substrate which does not decompose, deteriorate, or yellow even if it is irradiated with ultraviolet rays. For example, mixing a light stabilizer or the like in the aforementioned substrate can achieve the desired purpose. As the light stabilizer, TINUVIN 120, 144, etc., manufactured by Ciba Specialty Chemicals Co., Ltd. can be suitably used. When the wavelength of 300 nm or less is removed from the exposure light, the coloring, deterioration, and yellowing can be reduced.

The coating thickness of the liquid crystal mixture (in the case of a solution, the coating thickness after solvent drying) is preferably about 1 to 20 μm. When the coating thickness is thinner than 1 μm, the reflection bandwidth can be secured, but the degree of polarization tends to be inferior, which is not preferable. The coating thickness is preferably 2 μm or more, or even 3 μm or more. On the other hand, if it is thicker than 20 μm, the reflection bandwidth and the degree of polarization are not significantly improved, and it is not suitable because it increases the cost. The coating thickness is preferably 15 μm or less, more preferably 10 μm or less.

The method of coating the above-mentioned mixed solution on the oriented substrate may be, for example, a roll coating method, a gravure coating method, a spin coating method, a wire coating method, or the like. After the coating of the mixed solution, the solvent is removed to form a liquid crystal layer on the substrate. The conditions for removing the solvent are not particularly limited as long as the solvent can be removed, and the liquid crystal layer does not flow or flow. Usually, it is dried at room temperature, dried in a drying oven, The solvent is removed by heating or the like on a hot plate.

Next, the liquid crystal layer formed on the oriented substrate is in a liquid crystal state to orient the twist layer. For example, heat treatment is performed to make the liquid crystal layer a liquid crystal temperature range. The heat treatment method can be carried out in the same manner as the above drying method. The heat treatment temperature varies depending on the type of the liquid crystal material or the oriented substrate, and therefore cannot be generalized, but is usually 60 to 300 ° C, and preferably 70 to 200 ° C. Moreover, the heat treatment time varies depending on the heat treatment temperature and the type of the liquid crystal material or the oriented substrate used, so it cannot be generalized, and it is usually selected within the range of 10 seconds to 2 hours, and preferably in the range of 20 seconds to 30 minutes. .

The step of applying the liquid crystal mixture to the oriented substrate and irradiating with ultraviolet rays comprises the above steps (1) to (4).

Step (1), the liquid crystal mixture in a state of contacting with the oxygen-containing gas at a temperature of above 20 ℃, ultraviolet irradiation intensity of 20 ~ 200mW / cm ² of ultraviolet rays from the side of the alignment substrate 0.2 to 5 seconds. Thereby, the liquid crystal mixture is polymerized to form a polymer/oligomer having an average molecular weight of about 10,000 to 500,000, and the difference in reaction rate due to oxygen inhibition and the amount of radical generation due to ultraviolet absorption of the liquid crystal composition It is produced in the thickness direction of the oriented substrate side and the opposite side (oxygen interface side) to form a layer in which the amount of formation of the polymer/oligomer is continuously distributed in the thickness direction.

In the step (1), in order to cure and cure the liquid crystal mixture in a favorable orientation state, the temperature at the time of the first ultraviolet irradiation is 20 ° C or higher. On the other hand, the upper limit of the temperature is not particularly limited, and it is preferably 100 ° C or lower. If the temperature is higher than 100 ° C, diffusion will occur during irradiation and it is difficult to manage. From these points, the aforementioned temperature is preferably from 20 ° C to 50 ° C. A first ultraviolet light irradiation intensity of 20 ~ ² 00mW / cm 2, again 25 ~ 200mW / cm ^2, still preferably, 40 ~ 150mW / cm ² more preferably. When the ultraviolet irradiation intensity is less than 20 mW/cm ² , the polymerization in which the monomer distribution can be formed in the thickness direction cannot be completed, and the width cannot be made wide. Further, when the ultraviolet irradiation intensity is higher than 200 mW/cm ² , the polymerization reaction rate is higher than the diffusion rate, and the widening cannot be completed, which is not preferable.

In the step (1), the first ultraviolet irradiation time is 0.2 to 5 seconds, preferably 0.3 to 3 seconds, and more preferably 0.5 to 1.5 seconds. If it is shorter than 0.2 second, polymerization which can cause a monomer distribution in the thickness direction cannot be completed, and it is not possible to widen. Further, when it exceeds 5 seconds, the pitch change of the twisted-layer liquid crystal layer does not change continuously from the oriented substrate side to the oxygen interface side, and becomes discontinuous, which is not preferable. If a discontinuous change is formed, the coloring becomes severe when viewed from an oblique position.

The exposure environment at the time of ultraviolet irradiation is performed in a state where the liquid crystal mixture applied to the substrate is brought into contact with an oxygen-containing gas. The oxygen-containing gas preferably contains 0.5% or more of oxygen. The environment may be any environment that can be inhibited by oxygen polymerization, and generally can be carried out in an atmospheric environment. Further, the oxygen concentration may be increased or decreased depending on the wavelength width for the pitch control in the thickness direction and the speed required for the polymerization. In addition, Irgacure 184 and Irgacure 907 are used in an amount of about 1 to 5 parts by weight based on 100 parts by weight of the total of the polymerizable liquid crystal raw compound (A) and the polymerizable optically active agent (B). For the purpose of the Ciba Specialty Chemicals Co., Ltd., the desired purpose can be achieved, but the amount of the photopolymerization initiator (C) may be increased as a result.

Further, when the weight average molecular weight of the formed polymer/oligomer is too small at the time of the first ultraviolet ray irradiation, the diffusion rate is too high. Therefore, care should be taken not to homogenize the polymer/oligomer concentration gradient due to uncontrolled diffusion rates. It is necessary not only to form a large change in the thickness direction of the liquid crystal layer having a long pitch of the twist layer, but also to be able to maintain it. When the molecular weight of the polymer/oligomer is too low, the formed tilt cannot be maintained, and the structure disappears due to molecular diffusion. In order for the diffusion rate to satisfy the conditions governed by industrial conditions, it is necessary to form a polymer/oligomer in a range of a weight average molecular weight of about 10,000 to 500,000. The weight average molecular weight of the polymer/oligomer is preferably from 100,000 to 300,000. Further, the weight average molecular weight of the polymer/oligomer is a value measured by a GPC method. Further, the weight average molecular weight was calculated using a polyethylene oxide as a standard sample. Body: HLC-8120GPC made by TOSOH, pipe column: East SuperAWM-H+SuperAWM-H+SuperAW3000 (each 6mm ψ×15cm, 45cm), column temperature: 40°C, dissolving solution: 10mM-LiBr/NMP, flow rate: 0.4ml/min, inlet pressure: 8.5MPa Sample concentration: 0.1% NMP solution, detector: differential refractometer (RI).

When the concentration distribution formed by the first ultraviolet irradiation in the step (1) is directly immobilized, only the reflection wavelength band of the same level as that of JP-A-2002-286935 or the like can be obtained.

Therefore, in the step (2), the liquid crystal layer is heated at 70 to 120 ° C for 2 seconds or more in a state where the liquid crystal layer is brought into contact with the oxygen-containing gas. According to the step (2), in the step (1), the polymer/oligomer is formed to be inclined at a concentration in the thickness direction, and conversely, the residual concentration in the thickness direction of the formed unpolymerized monomer component is obliquely distributed in the thickness direction. Uniform, use it to carry out further pitch length expansion.

The heating temperature is preferably 70 ° C to 100 ° C. If it is less than 70 ° C, the diffusion speed is very slow, and it takes a long time to widen. And the orientation will gradually deteriorate, so it is not suitable. On the other hand, if it exceeds 120 ° C, the diffusion rate is too long to manage. The heating time is more than 2 seconds, or even more than 10 seconds. Only because of the one-sided Since the liquid crystal layer supported by the substrate has an oxygen interface, if the heating time is long, volatilization loss of the liquid crystal composition component, photopolymerization initiator, or the like, or poor flatness of the film surface, adhesion of foreign matter, or the like may occur. Practically, it is preferably 5 minutes or less or even 2 minutes or less.

By the heating homogenization step, as described above for a few seconds to several minutes, it is not necessary to perform heating in the dark. On the other hand, in the specification of No. 3272668, if the selective reflection band of the twisted layer liquid crystal is expanded by more than twice of the single pitch, an annealing time of 4 minutes or more is required, and a selective reflection bandwidth of 300 nm or more covering the visible light region is required. It takes about 2 hours to anneal.

In the specification No. 3272668, the expansion of the pitch length of the liquid crystal by the diffusion twisted layer remarkably takes a long time, and therefore it is necessary to maintain the molecular diffusion speed in the liquid crystal layer. Therefore, if the irradiation of light during heating is not avoided as much as possible, photopolymerization will occur during heating, and the pitch expansion cannot be obtained due to an increase in molecular weight or progress in crosslinking. This is because in the specification No. 3272668, since the substrate is held on both sides and is protected from oxygen, a polymer component having a slow diffusion rate is formed during the first ultraviolet irradiation, and the molecular mobility is low even if the polymerization degree is low. Still very low, this is an unavoidable disadvantage.

On the other hand, in the present invention, in the step (1), since the degree of polymerization due to the reverse use of oxygen is inferior, even in the same reaction conditions, the molecular weight of the produced reactant is low, and the diffusion rate can be secured. The condition for ensuring the diffusion speed is greatly alleviated, and even if the heating step is performed in a bright place for a short time, the expansion of the pitch length can be sufficiently completed. In this way, not only is the time significantly shortened, but also the line quality management, inspection, and measurement at the time of exposure are also dominant. When the line speed is 10m/min, in the specification No. 3272668, the annealing must be carried out in the dark. For up to 120 minutes, this processing is essentially impossible on the line. In the present invention, the above-described short time can be implemented, and practical problems are few.

Next, in the step (3), ultraviolet irradiation is performed for 10 seconds from the side of the oriented substrate at a temperature lower than the ultraviolet irradiation intensity of the step (1) in a state where the liquid crystal layer is brought into contact with the oxygen-containing gas at 20 ° C or higher. the above. By the second ultraviolet irradiation in the step (3), the effective depth of the polymerization inhibition caused by the oxygen permeated from the oxygen interface side is deeper than the step (1), so that the pitch of the short pitch field on the oxygen interface side is not substantially caused. The long change only proceeds the reaction in the long pitch region on the side of the oriented substrate, whereby the long pitch on the side of the oriented substrate is further increased.

As described above, the broadband irradiation is insufficient by the first ultraviolet irradiation alone. Therefore, in the step (2), after the polymer/oligomer polymer concentration gradient structure, that is, the pitch length change structure is maintained, the remaining unreacted monomers are homogenized, and then the step (3) is carried out. The second ultraviolet irradiation polymerizes the remaining monomer to form a pitch inclination. Thereby, the effective depth of the polymerization resistance caused by the oxygen permeated from the oxygen interface side can be made deeper than the step (1), so that the pitch length of the short pitch field on the oxygen interface side is not substantially changed, and only the oriented substrate side is made. The reaction in the long pitch field proceeds, whereby the long pitch on the oriented substrate side is further increased.

The increase in the molecular weight of the liquid crystal composition layer and the diffusion rate are inferior, and the difference is large compared to the first ultraviolet irradiation in the step (1), so that the amount of radicals generated per unit time is reduced, and the polymerization progress rate is lowered. Can be more broadband.

The second ultraviolet ray irradiation in the step (3) is carried out at a temperature of 20 ° C or higher. The upper limit of the temperature is not particularly limited, and is preferably 140 ° C or less. It is preferably 60 ° C ~ 140 ° C, more preferably 80 ° C ~ 120 ° C. If the temperature is lower than 20 ° C, the diffusion rate of the polymerizable liquid crystal original compound (A) is very slow, and it takes a long time to widen the frequency. Chemical.

The second ultraviolet irradiation is performed by irradiating the ultraviolet irradiation intensity lower than the first ultraviolet irradiation. When the illuminance is lower than the first ultraviolet ray irradiation, the oxygen polymerization resistance depth can be deeper than the oxygen resistance depth at the first ultraviolet ray irradiation, and the short wavelength band formed on the air interface side hardly changes, and the substrate side length is long. The wavelength bandwidth is frequencyd. Further, the second ultraviolet ray irradiation intensity is a range lower than the first ultraviolet ray irradiation intensity, and preferably 1 to 50 mW/cm ² .

The second ultraviolet irradiation time varies depending on the illuminance, and is generally 10 seconds or longer, and more preferably 30 seconds or longer. Further, the ultraviolet irradiation time is preferably 120 seconds or less, and more preferably 60 seconds or less, from the viewpoint of the operation time.

Further, in comparison with the embodiment of the specification No. 3272668, it can be seen that in the specification of No. 3272668, the irradiation intensity of the first ultraviolet irradiation and the second ultraviolet irradiation is the same. In this method, since the pitch expansion at the time of the second ultraviolet ray irradiation cannot be expected, it is necessary to depend on the diffusion at the time of annealing. Therefore, in the specification of No. 3272668, a long annealing time is required, which is a big problem in practical use.

Further, if the pitch length change in the step (1) has a defect such as discontinuity, the step (3) can be used to make it continuous. When the pitch length changes discontinuously, it may have unnecessary characteristics in the selective reflection wavelength band, such as only the specific wavelength can be deleted, or the transmittance is high. At this time, there is a problem that the color tone is uneven in the plane, or the color tone is colored. Even as described above, the wavelength characteristic shifts to a short wavelength at oblique incidence, so that when the bright wavelength spectrum of the light source is high/low in the field of the light source, an impulsive color tone and a change in brightness are caused, resulting in markedly inferior visuality. . It is best to try to eliminate this defect so that the reflectance wavelength within the band reflectance / transmittance The changes are few and flat. By the widening step of the step (3), the broadening of the step (1) is different in the ultraviolet irradiation condition, so even if the discontinuity of the pitch length change is temporarily generated, the wavelength domain formed in the step (1) is also formed. Different areas are produced, so the overlapping effect makes the whole disadvantages complementary, and the result can form a continuous change. In the case of the second embodiment, for example, in the second embodiment of the Japanese Patent Publication No. 2002-286935, a step is generated in the expanded band, but the present invention has continuous and smooth characteristics as shown in the later-described embodiment. . This is very advantageous in practical use.

As described above, the widening is achieved by the step (3), and the widening of the frequency shown in the following embodiment can be realized. The angle of view caused by the color shift and the discoloration caused by the blue shift of the oblique incident light becomes very large, and the viewing angle can be remarkably reduced. Coloring.

Next, in the step (4), ultraviolet rays are irradiated in the absence of oxygen. By the third ultraviolet irradiation, the torsion layer reflection band which is expanded in the steps (1) to (3) can be made inferior and hardened. Thereby, the pitch change configuration can be made inferior and fixed.

In the absence of oxygen, for example, it can be in an inert gas atmosphere. The inert gas is not particularly limited as long as it does not affect the ultraviolet polymerization of the liquid crystal mixture. Examples of the inert gas include nitrogen, argon, helium, neon, krypton, xenon, and the like. Among them, nitrogen is most commonly used, which is very suitable. Further, the transparent substrate may be bonded to the twisted layer liquid crystal layer to prevent oxygen from being present.

In the step (4), ultraviolet irradiation can be carried out from either the side of the oriented substrate or the side on which the liquid crystal mixture has been applied.

The ultraviolet irradiation conditions are not particularly limited as long as they are conditions for curing the liquid crystal mixture. Usually, the irradiation intensity of about 40 to 300 mW/cm ^{2 is} preferably about 1 to 60 seconds. The irradiation temperature is about 20 to 100 °C.

Thereby, the reliability can be remarkably improved by the increase in the crosslink density of the liquid crystal layer and the increase in the molecular weight. In the present invention, the first ultraviolet ray irradiation in the step (1) and the second ultraviolet ray irradiation in the step (3) are performed by ultraviolet irradiation from the surface side of the oriented substrate in order to actively use oxygen to be inhibited. Therefore, a large gradient can be formed in the thickness direction in the reaction rate, but the problem is that the hardness of the film surface is insufficient, the strength of the film is insufficient, or the long-term reliability is insufficient due to the low polymerization rate on the air interface side. Therefore, in the step (4), the third ultraviolet ray irradiation is performed in the absence of oxygen, and the residual monomer is polymerized and the film quality is strengthened. In this case, the reaction rate on the surface in an air environment (in the presence of oxygen) is not sufficiently increased, and the reaction rate is hardly higher than 90%. Therefore, in order to obtain sufficient reliability, it is preferred to perform ultraviolet irradiation in the absence of oxygen. The direction of irradiation is not particularly limited. It is preferable to irradiate from the liquid crystal layer side, but in the nitrogen atmosphere, the surface reaction can be sufficiently performed even when irradiated from the substrate side.

The twisted-layer liquid crystal film thus obtained can be used without being peeled off from the substrate, or can be used after being peeled off from the substrate.

The wide-band twisted layer liquid crystal film of the present invention can be used as a circularly polarizing plate. A λ/4 plate can be laminated on the circular polarizing plate as a linear polarizing element. It is preferable that the circularly polarizing plate, that is, the twisted-layer liquid crystal film, is laminated on the λ/4 plate in a state in which the pitch length is continuously narrowed.

The λ/4 plate is not particularly limited, and may be suitably used such as polycarbonate, polyethylene terephthalic acid, polystyrene, polyfluorene, polyvinyl alcohol, polymethyl methacrylate or the like to extend the pan of the phase difference. A transparent resin film or a normidine resin film such as an ARTON film manufactured by JSR Corporation is used. Further, if a phase difference plate that performs two-axis extension and compensates for a change in phase difference due to an incident angle is used, the viewing angle characteristics can be improved, which is preferable. In addition, in addition to extending the phase difference by the resin extension, it can also be used to The λ/4 plate obtained by, for example, λ/4 layer obtained by orienting the liquid crystal is used. At this time, the thickness of the λ/4 plate can be greatly reduced. The thickness of the λ/4 wavelength plate is usually 0.5 to 200 μm, preferably 1 to 100 μm.

A phase difference plate that functions as a λ/4 wavelength plate in a wide wavelength range such as a visible light region can be displayed, for example, by a phase difference layer that functions as a λ/4 wavelength plate with light-colored light having a wavelength of 550 nm. The phase difference layer of the other phase difference characteristics is obtained, for example, such that the phase difference layers functioning as the λ/2 wavelength plate overlap each other. Therefore, the phase difference plate disposed between the polarizing plate and the brightness enhancement film may be formed of one or two or more layers of retardation layers.

The absorbing polarizer can be used by being aligned on the transmission axis in the direction of the transmission axis of the linear polarizing element.

The polarizer is not particularly limited and various types can be used. As a polarizer, for example, a hydrophilic polymer film such as a polyvinyl alcohol film, a partially acetalized polyvinyl alcohol film, or a vinyl styrene acetate copolymer partial saponified film is adsorbed with iodine or dichroism. A polyene-based alignment film such as a uniaxially stretched dichroic material such as a dye, a dehydrated material of polyvinyl alcohol, or a dechlorinated product of polyvinyl chloride. Among them, a polarizer formed of a polyvinyl alcohol-based film and a dichroic substance such as iodine is preferred. The thickness of these polarizers is not particularly limited and is generally about 5 to 80 μm.

The uniaxially extending polarizer in which the polyvinyl alcohol-based film is dyed with iodine can be produced, for example, by immersing polyvinyl alcohol in an aqueous iodine solution, and stretching it to a length of 3 to 7 times. It may be immersed in an aqueous solution containing potassium iodide such as boric acid, zinc sulfate or zinc chloride as needed. Further, the polyvinyl alcohol-based film may be immersed in water and washed with water before dyeing. By washing the polyvinyl alcohol film with water, not only the dirt or the clogging inhibitor on the surface of the polyvinyl alcohol film can be washed, but also the polyvinyl alcohol is used. The membrane expands to prevent uneven effects such as staining mottle. The extension may be carried out after dyeing with iodine, or while dyeing, or after iodine. It may also be extended in an aqueous solution such as boric acid or potassium iodide or in a water bath.

The aforementioned polarizer is usually used as a polarizing plate provided with a transparent protective film on one side or both sides. The transparent protective film is excellent in transparency, mechanical strength, thermal stability, moisture shielding property, isotropic property, and the like. The transparent protective film may, for example, be a polyester polymer such as polyethylene terephthalate or polyethylene naphthalate, a cellulose polymer such as bisacetyl cellulose or triacetyl cellulose, or a poly A film formed of a transparent polymer such as a carbonate polymer or an acrylic polymer such as polymethacrylate. Further, a styrene-based polymer such as polystyrene, acrylonitrile/styrene copolymer, or a polyolefin having a structure of polyethylene, polypropylene, a ring system or a nor formamidine, or a vinyl propylene copolymer may be used. A film formed of a transparent polymer such as a polyolefin polymer, a vinyl chloride polymer, or a polyamide polymer such as nylon or aromatic polyamide. Further, an imine polymer, a fluorene polymer, a polyether fluorene polymer, a polyether ether ketone polymer, a polyphenylene sulfide polymer, a vinyl alcohol polymer, or a vinylidene chloride system A film formed of a transparent polymer such as a polymer, a polyvinyl butyral polymer, an allyl ester polymer, a polyoxymethylene polymer, an epoxy polymer, or a blend of the above polymers. In particular, it is preferable to use less optical refraction. From the viewpoint of the protective film of the polarizing plate, triacetyl cellulose, polycarbonate, acrylic polymer, cyclic polyolefin resin, polyolefin having a norform structure, and the like are suitable.

Further, the polymer film described in JP-A-2001-343529 (WO01/37007) may, for example, contain a thermoplastic resin having a substituted and/or unsubstituted guanamine group in the side chain of (A), and (B) ) having substituted and/or unsubstituted benzene on the side chain A resin composition of a base and a nitrile-based thermoplastic resin. Specific examples thereof include a film comprising a cross-polymer of isobutylene and N-methylbutyleneimine and a resin composition of an acrylonitrile styrene copolymer. As the film, a film formed of a mixed product of a resin composition or the like can be used.

A transparent protective film is a triacetyl cellulose film whose surface is saponified by alkali or the like, which is particularly suitable for the viewpoint of polarization characteristics or durability. The thickness of the transparent protective film can be appropriately determined, and is generally about 10 to 500 μm, particularly preferably 20 to 300 μm, and more preferably 30 to 200 μm, from the viewpoints of workability such as strength and handleability, and thin layer properties.

Further, the transparent protective film is preferably not colored as much as possible. Therefore, it is preferable to use: Rth=[(nx+ny)/2-nz]‧d (only, nx, ny is the main refractive index in the film plane, nz is the refractive index in the film thickness direction, and d is the film thickness) The phase difference in the film thickness direction indicated is a protective film of -90 nm to +75 nm. By using the phase difference (Rth) in the thickness direction of -90 nm to +75 nm, the coloring (optical dyeing) of the polarizing plate due to the protective film can be almost eliminated. The phase difference (Rth) in the thickness direction is preferably -80 nm to +60 nm, particularly preferably -70 nm to +45 nm.

The transparent protective film may be a transparent protective film formed of the same polymer material in the surface, or a transparent protective film formed of a different polymer material or the like.

The surface of the transparent protective film which is not followed by the polarizer may be subjected to a treatment for the purpose of the hard cover layer, the reflection preventing treatment, the adhesion prevention or diffusion, or even the anti-glare.

The hard cover treatment is carried out for the purpose of preventing the loss of the surface of the polarizing plate, and a hardened film excellent in hardness or sliding property formed by a suitable ultraviolet curable resin such as acrylic or polyoxygen can be added to the hard coat film. Transparent protective film watch The way to form. The reflection preventing treatment is performed for the purpose of preventing reflection of light outside the surface of the polarizing plate, and can be achieved by forming a conventional anti-reflection film or the like. Further, the adhesion prevention treatment is performed for the purpose of preventing adhesion to the adjacent layer.

Further, the anti-glare treatment is performed for the purpose of preventing external light from being reflected on the surface of the polarizing plate and obstructing the visual observation of the light transmitted through the polarizing plate, and the like, for example, by a sandblasting method such as a sandblasting method or an embossing method, Alternatively, a fine concavo-convex structure is formed on the surface of the transparent protective film by a suitable method such as a method of blending transparent fine particles. In the formation of the surface fine concavo-convex structure, as the fine particles contained therein, for example, ceria, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, cerium oxide, or the like having an average particle diameter of 0.5 to 50 μm can be used. The transparent fine particles such as the inorganic fine particles formed by the conductivity and the organic fine particles formed by the crosslinked or uncrosslinked polymer. When the surface fine uneven structure is formed, the amount of fine particles used is generally from 2 to 50 parts by weight, and preferably from 5 to 25 parts by weight, per 100 parts by weight of the transparent resin forming the surface fine uneven structure. The anti-glare layer can also serve as a diffusion layer (expanding the viewing angle function, etc.), and the polarizing plate can be diffused by light to expand the viewing angle and the like.

Further, the antireflection layer, the adhesion preventing layer, the diffusion layer, the antiglare layer, and the like may be provided on the transparent protective film, or may be provided as a separate transparent protective film as a separate use optical layer.

The linear polarizing element may be provided with an adhesive layer for adhering to other members such as a liquid crystal cell. The adhesive for forming the adhesive layer is not particularly limited, and for example, an acrylic polymer, a polyoxymethylene polymer, a polyester, a polyurethane, a polyamide, a polyether, a fluorine atom, or a rubber can be appropriately selected. The polymer is a matrix polymer To use. In particular, the acrylic pressure-sensitive adhesive is excellent in optical transparency, exhibits appropriate wettability, cohesiveness and adhesion properties, and is excellent in weather resistance and heat resistance, and is particularly preferably used.

In addition, in addition to the above, it is possible to prevent foaming or peeling due to moisture absorption or the like, to prevent deterioration of optical characteristics due to thermal expansion, or to warp the liquid crystal cell, and to have high quality and excellent durability. In order to form the liquid crystal display device, it is preferable to use an adhesive layer having a low moisture absorption rate and excellent heat resistance.

The adhesive layer may contain, for example, a resin of a natural product or a composition, particularly, such as an adhesive-imparting resin, glass fiber, glass beads, metal powder, a filler formed of other inorganic powder, or the like, a pigment, a colorant, or an antioxidant. Additives that can be added to the adhesive layer. Further, it may be an adhesive layer containing fine particles and exhibiting light diffusibility.

The attachment of the adhesive layer can be carried out in an appropriate manner. For example, an adhesive solution prepared by dissolving or dispersing a matrix polymer or a composition thereof in a solvent formed from a separate substance or mixture of a suitable solvent such as toluene or ethyl acetate may be used. And attaching it directly to the polarizing plate or the optical film by a suitable expansion method such as a flow-through method or a coating method, or forming an adhesive layer on the release film according to the above, and then moving it to the polarizing plate. The way on or on the optical film. The adhesive layer may be provided on one or both sides of the polarizing plate or the optical film as an overlapping layer of different compositions or types. Further, in the case of double-sided, an adhesive layer of different composition, type, thickness, or the like may be formed in the surface of the polarizing plate or the optical film. The thickness of the adhesive layer can be appropriately determined depending on the purpose of use or adhesion, and is generally 1 to 500 μm, preferably 5 to 200 μm, particularly preferably 10 to 100 μm.

Before the application is practical, for the purpose of preventing its contamination, the adhesion of the adhesive layer Temporarily attached to the release film to cover it. Thereby, contact with the adhesive layer can be prevented under the general processing state. In addition to the above-mentioned thickness conditions, the release film may be, for example, a suitable sheet of a plastic film, a rubber sheet, a paper, a cloth, a non-woven fabric, a net, a foamed sheet or a metal foil, or a laminate of these sheets, and may be used as needed. A suitable release agent such as an oxygen system, a long-chain alkyl group, a fluorine element or a molybdenum sulfide may be applied to a coating agent or the like as appropriate.

Further, in each layer such as an adhesive layer, it can be treated by, for example, a salicylate-based compound, a phenol-based compound, a benzotriazole-based compound, a cyanoacrylic compound, or a nickel-salt-based compound. In other ways, it has ultraviolet absorption energy and the like.

The linear polarizing element of the present invention can be suitably used in the formation of various devices such as a liquid crystal display device. The formation of the liquid crystal display device can be conventionally performed as a reference. In other words, the liquid crystal display device is generally formed by appropriately combining a liquid crystal cell, an adhesive optical film, and a component such as an illumination system as needed, into a drive circuit or the like, and the present invention uses the present invention. The polarizing plate or the optical film to be formed is not particularly limited, and may be a conventional method. As the liquid crystal cell, any type such as a TN type, an STN type, or a π type can also be used.

A liquid crystal display device in which a polarizing plate or an optical film is disposed on one side or both sides of a liquid crystal cell, or a liquid crystal display device in which a backlight or a reflector is used in an illumination system can be formed. At this time, the polarizing plate or the optical film formed by the present invention may be disposed on one side or both sides of the liquid crystal cell. When a polarizing plate or an optical film is provided on both sides, the same may be the same or different. Further, when the liquid crystal display device is formed, for example, a diffusion plate, an anti-glare layer, an anti-reflection film, a protective plate, a ruthenium array, a lens array film, a light diffusion plate, a backlight, or the like can be suitably disposed at a suitable position. The parts are configured in one or more layers.

Further, a circularly polarizing plate (reflecting polarizer) using the twisted-layer liquid crystal film is used in a polarizing element system in which at least two reflective polarizers (a) overlapping each other in a wavelength band in which polarization selective reflection is overlapped In the case where the front phase difference (normal direction) is almost zero and the phase difference layer (b) having λ/8 or more is incident on the incident light obliquely incident with respect to the normal direction by 30 or more. Further, the twisted layer liquid crystal film may be one side of the maximum pitch and the minimum pitch of the helical twisted molecular structure as the retardation layer (b) side, but from the viewpoint of the viewing angle (good viewing angle and small coloration), if the reflection is polarized Sub-(a) is expressed as (maximum pitch/minimum pitch), and is preferably configured to have a maximum pitch/minimum pitch/phase difference layer (b)/maximum pitch/minimum pitch. Further, as shown in Fig. 6, when the λ/4 plate is combined, it is preferable that the minimum pitch side of the reflected polarizer (a) is λ/4 plate side.

The polarizing element system, that is, a twisted layer liquid crystal laminate having a broadband selective reflection function, has a circular polarization reflection/transmission function in the front direction, and can be used as a wide frequency circular polarizing plate for a liquid crystal display device. In this case, it can be used as a circularly polarizing plate by a liquid crystal cell arranged in a circularly polarized pattern; for example, a light source side having a multi-domain transmissive VA type liquid crystal cell.

The retardation layer (b) has a phase difference of almost zero in the front direction and a phase difference of λ/8 or more with respect to incident light at an angle of 30° from the normal direction. The purpose of the front phase difference is to maintain the polarization of the normal incidence, so it is preferably below λ/10.

The incident light from the oblique direction can be appropriately determined in accordance with the angle at which the polarized light can be efficiently converted and totally reflected. For example, if it is completely totally reflected at an angle of about 60° from the normal line, the phase difference at 60° measurement may be determined as λ/2. However, due to the transmitted light by the reflected polarizer (a), the polarization state is also Depending on the birefringence of the C-plate property of the reflected polarizer itself, the phase difference when the normally inserted C plate is measured at the angle is less than λ/2. Since the phase difference of the C plate is more monotonous when the incident light is inclined, the incident light with an angle of 30° has a λ/8 or more as an effective total reflection at an angle of 30° or more. Standards are fine.

The material of the retardation layer (b) is not particularly limited as long as it has the optical characteristics as described above. For example, the planar orientation state of the torsion layer liquid crystal having a selective reflection wavelength other than the visible light region (380 nm to 780 nm), or the vertical alignment state of the fixed rod liquid crystal, or the tube beam phase orientation or phase using the discotic liquid crystal may be mentioned. A columnar orientation, a negative one-axis crystal orientation in the plane, a biaxially oriented polymer film, and the like.

In the present invention, a C plate having a planar orientation state of a twisted layer liquid crystal having a selective reflection wavelength, which is fixed in the visible light region (380 nm to 780 nm), is preferably used as a selective reflection wavelength of the twisted layer liquid crystal in the visible light region. Therefore, the choice of reflected light must not be in the visible light field. The selective reflection is determined in a single meaning by the optical pitch of the twisted layer liquid crystal and the refractive index of the liquid crystal. The value of the center wavelength of the selective reflection may be in the infrared field, but it may be slightly complicated due to the influence of the optical rotation, and therefore the ultraviolet portion at 350 nm or less is more preferable. The formation of the twisted layer liquid crystal layer can be performed simultaneously with the formation of the twisted layer of the reflective polarizer.

In the present invention, the C plate in a fixed vertical orientation state uses a liquid crystal thermoplastic resin or a liquid crystal monomer which exhibits nematic liquid crystal at a high temperature by irradiation with ionizing radiation such as electron beams or ultraviolet rays, or by heat. The polymerizable liquid crystal polymerized by the orientation aid, or a mixture thereof. The liquid crystal property may be liquid to heat or heat, but from the viewpoint of ease of control or ease of formation of a single domain, It is preferred to use a thermal liquid crystal. The vertical alignment system is obtained by, for example, coating the above-mentioned birefringent material on a film on which a vertically oriented film (long-chain alkyl decane or the like) is formed, exhibiting a liquid crystal state, and being fixed.

As a C plate using a discotic liquid crystal, a discotic liquid crystal material having a negative one-axis property such as a phthalocyanine or a triphenyl compound having a molecular enlargement in a plane, exhibiting a nematic phase or a column The phase is fixed and used as a liquid crystal material. For example, JP-A-6-82777 and the like can be referred to as a negative one-axis inorganic layered compound.

The C-plate oriented by the biaxial orientation of the polymer film can be oriented in parallel by a method of pressurizing the thermoplastic resin with a polymer film having positive refractive index anisotropy in a well-balanced 2-axis manner. A method of cutting out a crystal or the like is obtained.

The laminate of the respective layers may be placed only in an overlapping manner, and it is preferable to laminate the layers by an adhesive or an adhesive from the viewpoint of workability and light use efficiency. In this case, the adhesive or the adhesive is transparent and does not absorb in the visible light region, and the refractive index is preferably as close as possible to the refractive index of each layer based on the viewpoint of suppressing surface reflection. From this viewpoint, for example, an acrylic adhesive or the like can be suitably used. Each layer may be formed into a single domain by using a different orientation film or the like, and then sequentially stacked by a method such as transcribing a light-transmissive substrate, or an adhesive layer may be formed to form an orientation film or the like for orientation. The layers are directly formed in order.

In each layer and the (adhesive) layer, it is possible to add particles as the degree of diffusion, and to impart isotropic properties, or to add an ultraviolet absorber, an antioxidant, and a surfactant to impart adjustability during film formation. .

The polarizing element (twist layer liquid crystal laminate) of the present invention has a circularly polarized light reflection/transmission function, and can be used as a linear polarizing element that converts transmitted light into linearly polarized light by combining a λ/4 plate. The same as the foregoing can be exemplified as λ /4 board.

If the λ/4 plate is a single layer formed of a single material, it has a good function only for a specific wavelength, and for other wavelengths, there is a problem that the wavelength dispersion characteristic is inferior as a λ/4 plate. Therefore, if the λ/2 plate is laminated with the shaft angle, it can be practically unobstructed, and functions as a wide-band λ/4 plate in the entire visible light region. In this case, each of the λ/4 plate and the λ/2 plate may be the same material, or may be produced by a combination of another material obtained by the same method as the above λ/4 plate.

For example, in a wide-band circular polarizer laminated λ/4 plate (140 nm), a λ/2 plate (270 nm) is arranged at 17.5 degrees with respect to the axial angle. In this case, the transmission axis is 10 degrees with respect to the axis of the λ/4 plate. Since the bonding angle varies by the phase difference value of each phase difference plate, it is not limited to the above-described bonding angle.

The absorbing type polarizer is attached to the transmission axis by aligning the transmission axis direction of the linear polarizing element.

(Distribution of diffused reflector)

A diffuse reflection plate should be disposed on the lower side of the light guide plate (opposite side of the liquid crystal cell arrangement surface). The main component of the light reflected by the parallel actinic film is an oblique incident component, which is reflected back in the parallel actinic film and returns to the backlight direction. Here, when the reflector on the back side is highly reflective, the reflection angle is maintained, and the front direction cannot be emitted, and the light is lost. Therefore, in order to expand the scattered reflection component in the front direction without maintaining the reflection angle of the reflected light, it is preferable to dispose the diffuse reflection plate.

(Distribution board configuration)

In the present invention, the parallel actinic film and the backlight source should be appropriately diffused. board. Since the light reflected by oblique incidence is scattered near the backlight light guide body, and a part thereof is scattered toward the normal incident direction, the light reuse efficiency can be improved.

The diffusion plate to be used can be obtained by embedding fine particles having different refractive indices in the resin, in addition to the surface irregularities. The diffusing plate may be sandwiched between the parallel actinic film and the backlight, or may be attached to the parallel actinic film.

When the liquid crystal cell to which the parallel actinic film is attached is disposed close to the backlight, a Newton's ring may be generated between the surface of the film and the gap of the backlight, and the side surface of the light guide plate of the light parallelizing film in the present invention is disposed to have diffusion of surface unevenness The plate, thereby suppressing the occurrence of Newton's rings. Further, a layer having both a concavo-convex structure and a light-diffusing structure may be formed on the surface of the parallel actinic film of the present invention.

(configuration of viewing angle expansion film)

The viewing angle expansion in the liquid crystal display device of the present invention is such that the backlight is combined with the backlight which is parallelized, and the light having good display characteristics is obtained from the vicinity of the front surface of the liquid crystal display device, and the light is diffused to obtain uniformity in the entire viewing angle. And good display characteristics to get.

The viewing angle expanding film used herein uses a diffusing plate which is substantially free from the rear. The diffuser plate can be placed as a diffusion adhesive. The installation location is the visual side of the liquid crystal display device, and any of the polarizing plates can be used. However, in order to prevent the contrast caused by the infiltration of the pixels or the like, or the slightest residual, the contrast between the polarizing plate and the liquid crystal cell is preferably as close as possible to the layer close to the unit cell. Further, in this case, it is preferable to use a film which does not substantially eliminate the polarized light. A fine particle dispersion type diffusion plate disclosed in, for example, JP-A-2000-347006 and JP-A-2000-347007 can be suitably used.

When the viewing angle expansion film is located outside the polarizing plate, the liquid crystal layer - to the polarizing plate industry The light that is parallelized by the light is transmitted, so if it is a TN liquid crystal cell, it is not necessary to specifically use the viewing angle compensation phase difference plate. In the case of an STN liquid crystal cell, it is only necessary to use a retardation film which can be favorably compensated only by the front surface characteristics. In this case, since the viewing angle widening film has an air surface, it is also possible to adopt a type in which the surface shape causes a refractive effect.

On the other hand, when the viewing angle widening film is inserted between the polarizing plate and the liquid crystal layer, the light is diffused at the stage of transmitting the polarizing plate. In the case of TN liquid crystal, the viewing angle characteristics of the polarizer itself need to be compensated. In this case, it is necessary to insert a phase difference plate that compensates for the viewing angle characteristics of the polarizer between the polarizer and the viewing angle widening film. In the case of the STN liquid crystal, in addition to the front phase difference compensation of the STN liquid crystal, it is necessary to insert a phase difference plate that compensates for the viewing angle characteristic of the polarizer.

A micro-lens array film or a full-image film-like viewing angle-enlarging film having a regular structure as in the prior art, and a black matrix of a liquid crystal display device or a conventional backlight parallelizing optical system The fine structures such as the microlens array/稜鏡 array/griver/micro mirror array interfere with each other to easily generate moiré. However, the parallel actinic film of the present invention does not have a regular structure in the plane, and the emitted light does not have a regular tone change, so that it is not necessary to consider the degree of cooperation or the order of arrangement with the viewing angle enlargement film. Therefore, the viewing angle widening film is not particularly limited as long as it does not interfere with the pixel black matrix of the liquid crystal display device, and the selection is wide.

In the present invention, the viewing angle widening film can be used as it is, and the light-scattering plate described in Japanese Laid-Open Patent Publication No. 2000-347006, No. 2000-347007, and the degree of twisting is 80%. 90%. Others, the full-image sheet, the micro-turn matrix, the microlens array, etc., even if the internal structure has a regular structure, as long as the pixel black matrix interference/moire of the liquid crystal display device is not formed, use.

Further, the liquid crystal display device can be produced by appropriately using various optical layers or the like according to a usual method.

Example

The invention is illustrated by the following examples and comparative examples, but the invention is not limited by these examples.

Example 1

In the photopolymerizable mesogen compound (polymerizable nematic liquid crystal monomer using the compounds of Table 120, molar extinction coefficient of ^{1dm 3 mol -1 cm -1 @ 365nm} , 2100dm 3 mol -1 cm -1 @ 334nm, 36000dm ³ mol ^-1 cm ^-1 @314nm. Purity >99%) 94.8 parts by weight, polymerizable optically active agent (LC756, manufactured by BASF Corporation) 5.2 parts by weight and solvent (cyclopentanone), mixed and mixed to form a selective reflection center wavelength of 550 nm In the solution, 3 wt% of a photopolymerization initiator (Irgacure 907, manufactured by Ciba Specialty Chemicals Co., Ltd.) was added to the solution to prepare a coating liquid (solid content: 30% by weight). The coating liquid was applied to an extended polyethylene terephthalate film (oriented substrate) by a wire ingot so that the thickness after drying was 6 μm, and the solvent was dried at 100 ° C for 2 minutes. On the obtained film, the first ultraviolet ray was irradiated for 1 second at 50 mW/cm ² from the oriented substrate side in an air atmosphere of 40 °C. Then, it was heated at 90 ° C for 1 minute in the absence of ultraviolet irradiation (the selective reflection wavelength at this time was 420 to 650 nm). Next, the second ultraviolet ray was irradiated at 5 mW/cm ² for 60 seconds in an air atmosphere of 90 ° C (the selective reflection wavelength at this time was 420 to 900 nm). Subsequently, the third ultraviolet ray was irradiated for 30 seconds from the oriented substrate side at 80 mW/cm ² in a nitrogen atmosphere at 50 ° C to obtain a wide-band twisted-layer liquid crystal film having a selected wavelength of 420 to 900 nm. The reflection spectrum of the wide-band twisted layer liquid crystal film is shown in Fig. 4.

A negative two-axis phase difference plate was formed on the upper portion of the obtained wide-band twisted-layer liquid crystal film (circular polarized reflection plate) by using a light-transmitting adhesive. The negative two-axis phase difference plate was obtained by the following method. In other words, cyclopentanone was added as a solvent to 93 parts by weight of a photopolymerizable nematic liquid crystal monomer (LC242, manufactured by BASF Corporation) and 7 parts by weight of a polymerizable optically active agent (LC756, manufactured by BASF Corporation), and the solution was made 30% by weight. After the concentration is adjusted and mixed to a wavelength of the selective reflection center of 350 nm, 5% by weight of a photopolymerization initiator Irgacure 907 is added to the solid component to prepare a coating liquid, and the solution is applied to the extended polyethylene pair by a wire ingot. The phthalate substrate was dried to a thickness of 4 μm, and the solvent was dried at 100 ° C for 2 minutes. Then, after the temperature is once raised to the isotropic transfer temperature of the liquid crystal monomer, it is gradually cooled to form a layer having a uniform orientation state. The obtained layer was subjected to ultraviolet irradiation at 50 mW/cm ^{2 for} 5 seconds in a fixed orientation state to obtain the phase difference plate. The phase difference of the negative two-axis phase difference plate was measured, and the light having a wavelength of 550 nm was 2 nm in the front direction, and the phase difference at the time of measurement by 30° was 120 nm. Further, the measurement of the phase difference was carried out by KOBRA-21ADH manufactured by Oji Scentific Instruments.

Further, in the upper portion, a light-transmitting adhesive was used in the same manner, and a circularly polarizing reflector having the same laminated layer as described above was copied, and a polarizing element was obtained. A λ/4 plate (front surface retardation of 140 nm) obtained by stretching a polycarbonate film on one axis was obtained on the obtained polarizing element to obtain a linear polarizing element. A polarizing plate (TEG1465DU, manufactured by Nitto Denko Corporation) was bonded to the linear polarizing element so that the transmission axis direction was uniform, and a polarizing plate-integrated polarizing element was obtained.

Example 2

In the first embodiment, on the linear polarizing element obtained by laminating the λ/4 plate of the polarizing element, the λ/2 plate obtained by axially extending the polycarbonate film on the λ/4 plate (front phase difference 270 nm) ), and a linear polarizing element is obtained. A polarizing plate (TEG1465DU, manufactured by Nitto Denko Corporation) was bonded to the linear polarizing element, and the direction of the transmission axis was aligned to obtain a polarizing plate-integrated polarizing element. These laminates are formed by the angles of the extension axes (phase retardation axes) of the λ/4 plate and the λ/2 plate and the extension axis (absorption axis) of the polarizing plate as shown in Fig. 3 . In Fig. 3, PL is an absorbing polarizing plate, C1 is a λ/4 plate (front surface difference of 140 nm), and C2 is λ/2 plate (front surface difference of 270 nm). The arrow of PL indicates the extension axis (longitudinal direction), θ 1 is 17.5°, and θ 2 is 80°.

Example 3

The polarizing element obtained in Example 1 was subjected to a λ/4 plate obtained by biaxially stretching a polycarbonate film (front surface retardation: 125 nm, Nz coefficient - 1.0) to obtain a linear polarizing element. A polarizing plate (TEG1465DU, manufactured by Nitto Denko Corporation) was bonded to the linear polarizing element to make the transmission axis direction uniform, and a polarizing plate-integrated polarizing element was obtained.

Comparative example 1

The coating liquid containing the liquid crystal mixture prepared in Example 1 was applied to the extended polyethylene terephthalate film (oriented substrate) by wire ingot to have a thickness of 6 μm after drying, and the solvent was 100. Dry at °C for 2 minutes. On the obtained film, ultraviolet irradiation was carried out at 50 mW/cm ² for 10 seconds from the oriented substrate side in an air atmosphere of 40 ° C, and the selective reflection wavelength was 420 to 800 nm at this time. Subsequently, ultraviolet irradiation was carried out at 80 mW/cm ² for 30 seconds from the oriented substrate side in a nitrogen atmosphere at 50 ° C to obtain a wide-band twisted-layer liquid crystal film having a selected wavelength of 420 to 800 nm. The reflection spectrum of the wide-band twisted layer liquid crystal film is shown in Fig. 4.

In the same manner as in the first embodiment, the same negative two-axis phase difference plate as in the first embodiment was applied to the upper portion of the obtained wide-band twisted layer liquid crystal film (circular polarized reflection plate) by using a light-transmitting adhesive.

Further, in the upper portion, a light-transmitting adhesive was used in the same manner, and a circularly polarizing reflector having the same laminated layer as described above was copied, and a polarizing element was obtained. A λ/4 plate (front surface retardation of 140 nm) obtained by stretching a polycarbonate film on one axis was obtained on the obtained polarizing element to obtain a linear polarizing element. A polarizing plate (TEG1465DU, manufactured by Nitto Denko Corporation) was bonded to the linear polarizing element so that the transmission axis direction was uniform, and a polarizing plate-integrated polarizing element was obtained.

Comparative example 2

The coating liquid containing the liquid crystal mixture prepared in Example 1 was applied to the extended polyethylene terephthalate film (oriented substrate) by wire ingot to have a thickness of 6 μm after drying. The solvent was dried at 100 ° C for 2 minutes. On the obtained film, ultraviolet irradiation was performed for 1 second at 50 mW/cm ² from the oriented substrate side in an air atmosphere of 40 °C. Then, it was heated at 90 ° C for 1 minute in the absence of ultraviolet irradiation (the selective reflection wavelength at this time was 420 to 650 nm). Subsequently, ultraviolet irradiation was carried out at 80 mW/cm ² for 30 seconds from the oriented substrate side in a nitrogen atmosphere at 50 ° C to obtain a wide-band twisted-layer liquid crystal film having a selected wavelength of 420 to 650 nm. The reflection spectrum of the wide-band twisted layer liquid crystal film is shown in Fig. 4.

In the same manner as in the first embodiment, the same negative two-axis phase difference plate as in the first embodiment was applied to the upper portion of the obtained wide-band twisted layer liquid crystal film (circular polarized reflection plate) by using a light-transmitting adhesive.

Further, in the upper portion, a light-transmitting adhesive was used in the same manner, and a circularly polarizing reflector having the same laminated layer as described above was copied, and a polarizing element was obtained. A λ/4 plate (front surface retardation of 140 nm) obtained by stretching a polycarbonate film on one axis was obtained on the obtained polarizing element to obtain a linear polarizing element. A polarizing plate (TEG1465DU, manufactured by Nitto Denko Corporation) was bonded to the linear polarizing element so that the transmission axis direction was uniform, and a polarizing plate-integrated polarizing element was obtained.

Comparative example 3

The coating liquid containing the liquid crystal mixture prepared in Example 1 was applied to the extended polyethylene terephthalate film (oriented substrate) by wire ingot to have a thickness of 6 μm after drying. The solvent was dried at 100 ° C for 2 minutes. On the obtained film, ultraviolet irradiation was performed for 1 second at 50 mW/cm ² from the oriented substrate side in an air atmosphere of 40 °C. Then, it was heated at 90 ° C for 1 minute in the absence of ultraviolet irradiation (the selective reflection wavelength at this time was 420 to 650 nm). Next, ultraviolet irradiation was performed at 5 mW/cm ² for 60 seconds in an air atmosphere of 90 ° C (the selective reflection wavelength at this time was 420 to 900 nm).

In the same manner as in the first embodiment, the same negative two-axis phase difference plate as in the first embodiment was applied to the upper portion of the obtained wide-band twisted layer liquid crystal film (circular polarized reflection plate) by using a light-transmitting adhesive.

Further, in the upper portion, a light-transmitting adhesive was used in the same manner, and a circularly polarizing reflector having the same laminated layer as described above was copied, and a polarizing element was obtained. A λ/4 plate (front surface retardation of 140 nm) obtained by stretching the polycarbonate film one-axis on the obtained polarizing element was obtained to obtain a linear polarizing element. A polarizing plate (TEG1465DU, manufactured by Nitto Denko Corporation) was bonded to the linear polarizing element so that the transmission axis direction was uniform, and a polarizing plate-integrated polarizing element was obtained.

(liquid crystal display device)

The polarizing plate-integrated polarizing element obtained in each of the above examples was used as a lower plate of a TFT-LCD, and on the other hand, spherical cerium oxide particles were embedded in an acrylic adhesive (thickness: 25 μm, refractive index: 1.47). (Refractive index: 1.44, diameter: 4 μm, and 20% by weight of the light-scattering adhesive (80%) was used as the upper plate side, and a laminated polarizing plate (TEG1465DU, manufactured by Nitto Denko Corporation).

Further, a cold cathode tube having a diameter of about 3 mm was placed on the side surface of the light guide body having a fine 稜鏡 structure, and was covered with a light source holder formed of a silver vapor-deposited polyethylene terephthalate film. A silver vapor-deposited polyethylene terephthalate film reflector is disposed under the light guide plate, and a polyethylene terephthalate film having a scattering layer formed of styrene bubbles is formed on the surface of the light guide plate. This is disposed as a light source on the lower side of the polarizing plate-integrated polarizing element.

The case of using the polarizing plate-integrated polarizing element of the first and third embodiments and the comparative examples 1 to 3 is the first drawing, and the case of using the polarizing plate-integrated polarizing element of the second embodiment is the second drawing.

In the first and second figures, the reference numerals are as follows, that is, PL is an absorbing polarizing plate, D is a viewing angle widening film (diffusion bonding material), LC is a liquid crystal cell, C1 is a λ/4 plate, and C2 is λ/ 2 plate, A is a reflective polarizer (a): a circular polarizer, B is a phase difference plate (b): C plate, S is a side light type light guide plate, and R is a diffuse reflection plate. Further, X is a polarizing element, Y is a linear polarizing element, and Z is a polarizing-integrated linear polarizing element.

<Evaluation method>

The wide-frequency torsion layer liquid crystal film (circularly polarized reflection plate) and the polarizing plate-integrated polarizing element obtained above were evaluated as follows. The results are shown in Table 2. Also, implementation The respective step conditions of the examples and comparative examples are also shown in Table 2.

(Selecting the reflection wavelength band and bandwidth (△λ))

The reflection spectrum of the wide-band torsion layer liquid crystal film was measured by a spectrophotometer (manufactured by Otsuka Electronics Co., Ltd., instantaneous multi-photometry system MCPD2000) to obtain a selective reflection wavelength band and a half-value bandwidth Δλ. The half-valued bandwidth Δλ is used as the reflection bandwidth of the half-reflectivity at one of the maximum reflectances.

(pitch change)

The cross-sectional TEM photograph was used to measure the width of the broadband twisted layer liquid crystal film in the vicinity of the ultraviolet irradiation surface (lower layer of 1 μm from the ultraviolet irradiation surface) and the vicinity of the air interface (lower layer of 1 μm from the air interface) and the middle thereof.

(reliability)

The wide-frequency twisted-layer liquid crystal film was respectively subjected to a reliability test at 80 ° C and 90 ° C of 90 ° R for 500 hours, and it was evaluated whether or not the precipitation of the powdery substance was observed on the surface.

○: No precipitates.

×: There is a precipitate.

(front brightness)

The polarizing plate-integrated polarizing element was placed on a halftone printing type backlight, and the polarizing plate side was placed thereon, and evaluated by a luminance meter (manufactured by TOPCON, BM-7).

(the color change of the tilt)

The change in color tone of the tilt of the liquid crystal display device was evaluated by the ELDIM viewing angle measuring device EZ-CONTRAST on the basis of the following criteria.

Δxy=((x ₀ -x ₁ ) ² +(y ₀ -y ₁ ) ₂ ) ^0.5

Frontal chromaticity (x ₀ , y ₀ ), chromaticity from the inclination ±60° (x ₁ , y ₁ )

Good: The change in hue of Δxy at a viewing angle of 60° is less than 0.04.

Poor: The change in hue of Δxy at a viewing angle of 60° is 0.04 or more.

In the embodiment, a twisted layer liquid crystal film having a selective reflection wavelength in a wide frequency band including a long wavelength region can be obtained. The twisted layer liquid crystal film is highly reliable, and the polarizing element used as the circular polarizing plate is also excellent in brightness enhancement characteristics. Further, the liquid crystal display device using the polarizing element separates the display information in the field of no inversion and reversal in the oblique direction by light diffusion, so that it is difficult to generate a color tone change or a harmonic inversion from the oblique direction, and a liquid crystal display having a wide viewing angle can be obtained. Device.

Industrial availability

The wide-band twisted layer liquid crystal film obtained by the manufacturing method of the present invention can be used as a circular polarizing plate (reflective type polarizer), and the circular polarizing plate can be used for a linear polarizing element, Lighting devices, liquid crystal display devices, and the like.

PL‧‧‧Absorbing polarizer

D‧‧‧ viewing angle expansion film (diffusion adhesive)

LC‧‧‧Liquid Crystal Cell

C1‧‧‧λ/4 board

C2‧‧‧λ/2 board

A‧‧‧Reflected photon (a): circular polarizer

B‧‧‧Phase plate (b): C plate

S‧‧‧Side light guide plate

R‧‧‧ diffuse reflector

X‧‧‧ polarizing element

Y‧‧‧linear polarizing element

Z‧‧‧Polarized integrated linear polarizing element

Fig. 1 is a conceptual diagram of an enlarged liquid crystal display device using the viewing angles of the polarizing plate-integrated polarizing elements of Examples 1 and 3 and Comparative Examples 1 to 3.

Fig. 2 is a conceptual view showing an enlarged liquid crystal display device by the viewing angle of the polarizing plate-integrated polarizing element of the second embodiment.

Fig. 3 is a view showing the axial angles of the respective layers in the polarizing plate-integrated polarizing element of the second embodiment.

Fig. 4 is a reflection spectrum of the twisted layer liquid crystal film produced in Example 1, Comparative Example 1, and Comparative Example 2.

PL‧‧‧Absorbing polarizer

D‧‧‧ viewing angle expansion film (diffusion adhesive)

LC‧‧‧Liquid Crystal Cell

C1‧‧‧λ/4 board

A‧‧‧Reflected photon (a): circular polarizer

B‧‧‧Phase plate (b): C plate

S‧‧‧Side light guide plate

R‧‧‧ diffuse reflector

X‧‧‧ polarizing element

Y‧‧‧linear polarizing element

Z‧‧‧Polarized integrated linear polarizing element

Claims (20)

A method for producing a wide-band twisted layer liquid crystal film comprising the steps of applying a liquid crystal mixture containing a polymerizable liquid crystal precursor compound (A) and a polymerizable optically active agent (B) to an oriented substrate, and irradiating the liquid crystal mixture with ultraviolet rays a step of polymerizing and hardening to produce a wide-band twisted-layer liquid crystal film having a reflection bandwidth of 200 nm or more, wherein the ultraviolet polymerization step comprises: bringing the liquid crystal mixture into contact with an oxygen-containing gas at a temperature of 20 ° C or higher, a step (1) of ultraviolet irradiation for 0.2 to 5 seconds from the side of the oriented substrate by ultraviolet irradiation intensity of 20 to 200 mW/cm ² ; and then, in a state where the liquid crystal layer is brought into contact with an oxygen-containing gas, at 70 to 120 And (C) heating at ° C for 2 seconds or more; then, in the state where the liquid crystal layer is brought into contact with the oxygen-containing gas, at a temperature of 20 ° C or higher, the ultraviolet ray irradiation intensity lower than the step (1), from the aforementioned orientation group Step (3) of irradiating the material side with ultraviolet rays for 10 seconds or more; then, step (4) of irradiating ultraviolet rays in the absence of oxygen. The method for producing a wide-band twisted-layer liquid crystal film according to claim 1, wherein the pitch length change of the wide-band twisted-layer liquid crystal film is continuously narrowed from the side of the oriented substrate. The method for producing a wide-band twisted-layer liquid crystal film according to the first aspect of the invention, wherein the polymerizable liquid crystal original compound (A) has one polymerizable functional group, and the polymerizable optically active agent (B) has two or more polymerizations. Sex functional group. The method for producing a broadband twisted layer liquid crystal film according to claim 1, wherein the polymerized liquid crystal original compound (A) has a molar extinction coefficient of 0.1 to 500 dm ³ mol ^-1 cm ^-1 @365 nm, 10 to 30000 dm. ³ mol ^-1 cm ^-1 @334 nm, and 1000~100000 dm ³ mol ^-1 cm ^-1 @314 nm. The method for producing a wide-band twisted layer liquid crystal film according to claim 1, wherein the polymerizable liquid crystal original compound (A) is represented by the following general formula (1): a compound represented by the formula (wherein R ₁ to R ₁₂ may be the same or different and represent -F, -H, -CH ₃ , -C ₂ H ₅ or -OCH ₃ , and R ₁₃ represents -H or -CH ₃ , X ₁ represents a general formula (2): -(CH ₂ CH ₂ O) _a -(CH ₂ ) _b -(O) _c -, X ₂ represents -CN or -F, and only a in the general formula (2) is An integer from 0 to 3, b is an integer from 0 to 12, c is 0 or 1, and b=0, c=0 when a=1~3, b=1~12, c=0~ when a=0 1). A circular polarizing plate is a wide-band twisted-layer liquid crystal film obtained by the manufacturing method of the first application of the patent application. A polarizing element is disposed between at least two reflective polarizers (a) in which wavelength bands of selective polarization of polarized light overlap each other, and has a front phase difference (normal direction) of almost zero and 30 relative to a normal direction The incident light having obliquely incident above has a retardation layer (b) of λ/8 or more, wherein the reflective polarizer (a) is a circularly polarizing plate of claim 6 of the patent application. The polarizing element of claim 7, wherein the selective reflection wavelength of the at least two reflective polarizers (a) overlaps each other in a wavelength range of 550 nm ± 10 nm. The polarizing element of claim 7, wherein the phase difference layer (b) is a plane orientation for fixing a liquid crystal phase of a twisted layer having a selective reflection wavelength range outside the visible light region for fixing the rod-shaped liquid crystal. In the vertical orientation state, the phase of the phase of the discotic liquid crystal or the orientation of the tube bundle phase is used to orient the polymer film 2 or to fix the inorganic lamellar compound having a negative 1 axis. The normal direction of the face constitutes the optical axis. A linear polarizing element is formed by laminating a λ/4 plate on a polarizing element of claim 7 to obtain a linear polarizer. For example, in the linear polarizing element of claim 10, the twisted layer liquid crystal film of the laminated circular polarizing plate is formed on the λ/4 plate so that the pitch length is continuously narrowed. The linear polarizing element according to claim 10, wherein the λ/4 plate is subjected to phase difference correction of the oblique incident light of the 2-axis extension to improve the phase difference plate of the viewing angle. The linear polarizing element according to claim 10, wherein the λ/4 plate is a liquid crystal polymer type retardation film obtained by coating and fixing a nematic liquid crystal or a matrix liquid crystal. The linear polarizing element according to claim 10, wherein the λ/4 plate is represented by the formula (nx-nz) when the principal refractive index in the plane is nx, ny, and the main refractive index in the thickness direction is nz. The (nx-ny) defined Nz coefficient satisfies -0.5~-2.5. A linear polarizing element is a layer of λ/2 plate laminated on a λ/4 plate of a linear polarizing element of claim 10 of the patent application. A linear polarizing element is such that the transmission axis direction of the absorbing polarizer is aligned with the transmission axis of the linear polarization element of claim 10, and the absorbing type photon is laminated on the λ/4 plate side of the linear polarization element. A illuminating device is provided on the surface side of a surface light source having a reflective layer on the inner side thereof, and has a linear polarizing element of claim 10 of the patent application. A liquid crystal display device having a liquid crystal cell on the light exit side of the illumination device of claim 17 of the patent application. A viewing angle-enhancing liquid crystal display device is disclosed in the liquid crystal display device of claim 18, wherein a viewing angle-enlarging film that diffuses light passing through a visual side of the liquid crystal cell is disposed on a visual side of the liquid crystal cell. The liquid crystal display device is expanded from the viewpoint of the application of the ninth aspect of the patent application, and a diffusion plate having substantially no rear dispersal and polarization elimination is used as the viewing angle expansion film.