JP2005015775A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device capable of displaying more excellent large-sized screen by finding out a liquid crystalline material suitable for manufacturing a liquid crystal display device with large-sized screen display, excellent in compatibility with a substrate, low in viscosity and having high specific resistance and a high electric voltage-holding rate. <P>SOLUTION: This liquid crystal display device is provided with a display manufactured by a liquid crystal dropping process using a nematic liquid crystal composition with positive dielectric anisotropy comprising a fluorine-containing compound with ≥4 fluorine atoms. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device including a display body prepared by a liquid crystal dropping method using a liquid crystal composition containing a specific fluorine-containing compound as a main component.

  Since liquid crystal display devices can be reduced in weight and thickness and have low power consumption, they are widely used as display bodies for watches, calculators, televisions, word processors, personal computers, and the like.

  Conventionally, liquid crystal display devices are often used for relatively small screens such as watches and calculators. However, in recent years, since it is possible to reduce the weight and thickness, it has been replaced even in applications where CRT has been used. In particular, there is a strong demand for larger screens for monitor applications such as televisions.

  However, the liquid crystal display device has problems such as a contrast, a viewing angle, and a luminance in increasing the screen size, and has a problem that it takes a long time in the manufacturing process of the liquid crystal cell of the liquid crystal composition.

  Conventionally, the liquid crystal material is injected by a vacuum injection method after bonding the glass substrates. However, this method takes 8 hours or more even with a 14-inch panel, and the operation efficiency is poor, which is a major obstacle in manufacturing. It was. As a solution for solving this problem, a liquid crystal dropping method has been proposed. The liquid crystal dropping method is a method in which a liquid crystal composition is dropped in a frame pattern formed by applying a sealant to the periphery of an image display region provided on one of two plane parallel support plates, and then the support plate and This is a method for producing a display body by pasting together with another support plate and then curing the above sealing agent with light or heat. This method can greatly shorten the manufacturing process.

  However, the liquid crystal material used in the liquid crystal dropping method needs characteristics such as low viscosity, excellent resistance to heat and light, and excellent compatibility with the support plate.

  Several patents have been filed regarding the liquid crystal dropping method. For example, Patent Document 1 below proposes a method of curing a sealing agent with ultraviolet rays through a filter that cuts ultraviolet rays of a specific wavelength. However, there is no description of a suitable liquid crystal material, and the following Patent Document 2 proposes a liquid crystal material used in a liquid crystal display device obtained by a liquid crystal dropping method, and proposes a suitable liquid crystal material. However, the liquid crystal material proposed here is a compound having negative dielectric anisotropy and cannot be suitably used for liquid crystal display devices other than the vertical alignment type.

JP-A-8-101395 JP 2002-122870 A

  Accordingly, an object of the present invention is to provide a liquid crystal having excellent affinity with a support plate, low viscosity, high specific resistance and high voltage holding ratio, and suitable for manufacturing a liquid crystal display device having a large-screen display. It is an object of the present invention to provide a liquid crystal display device that can find a material and can display a larger screen.

  As a result of intensive studies, the present inventors have found that a nematic liquid crystal composition containing a specific fluorine-containing compound can satisfy the above object.

  The present invention has been made on the basis of the above knowledge, and includes a nematic liquid crystal composition containing a fluorine-containing compound represented by any one of the following formulas Ia to Ii and having 4 or more fluorine atoms, and having positive dielectric anisotropy. An object of the present invention is to provide a liquid crystal display device comprising a display body made by using a liquid crystal dropping method.

  ADVANTAGE OF THE INVENTION According to this invention, the liquid crystal display device in which the outstanding large screen display is possible can be provided by using the display body by a liquid crystal dropping method, especially the nematic liquid crystal composition suitable for preparation of a large screen display.

  Hereinafter, the liquid crystal display device of the present invention will be described in detail.

In the above formulas Ia to Ii, examples of the alkyl group represented by R ₁ include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, vinyl, allyl, butenyl, ethynyl, propynyl, butynyl, Methoxymethyl, ethoxymethyl, propoxymethyl, butoxymethyl, methoxyethyl, ethoxyethyl, perfluoromethyl, perfluoroethyl, perfluoropropyl, monofluoromethyl, difluoromethyl, 2,2,2-trifluoromethyl, perfluorovinyl Perfluoroallyl, isopropyl, 1-methylpropyl, 2-methylpropyl, 2-butylmethyl, 3-methylbutyl, 2-methylpentyl, 3-methylpentyl, 2-ethylhexyl, 2-propylpentyl, 1-methylpentyl, etc. It is below.

  More specific embodiments of the fluorine-containing compound represented by any one of the above formulas Ia to Ii and having 4 or more fluorine atoms are shown below. However, the present invention is not limited by the following specific examples.

  The nematic liquid crystal composition used in the liquid crystal display device of the present invention contains a fluorine-containing compound represented by any one of the formulas Ia to Ii and having 4 or more fluorine atoms. The content of the fluorine-containing compound in the nematic liquid crystal composition is preferably 5% by mass or more, more preferably 10 to 100% by mass, and most preferably 40 to 100% by mass.

  The nematic liquid crystal composition comprises: a) 40 to 100% by mass, particularly 60 to 100%, of a liquid crystal component A composed of one or more compounds having a dielectric anisotropy greater than +1.5 including the fluorine-containing compound. % By mass, b) 0 to 40% by mass, particularly 0 to 40% by mass of a liquid crystal component B composed of one or more compounds having a dielectric anisotropy of −1.5 to +1.5 represented by the following formula II It is preferable to contain 0 to 20% by mass, particularly 0 to 10% by mass of the liquid crystal component C composed of one or more compounds having a dielectric anisotropy smaller than 30% by mass and c) -1.5. The content of the fluorine-containing compound in the liquid crystal component A is preferably selected so that the content of the fluorine-containing compound in the nematic liquid crystal composition is in the above-described range.

In the above formula II, examples of the alkyl group represented by R ₂ and R ₃ include groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, and nonyl. R ₂ and R ₃ Examples of the alkoxy group represented by the formula include groups such as methoxy, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy, heptyloxy, octyloxy, nonyloxy, and the like, and the ω-fluoroalkyl group represented by R ₂ and R ₃ Examples include groups such as monofluoromethyl, difluoromethyl, trifluoromethyl, and 2,2,2-trifluoromethyl.

  Specific embodiments of the compound represented by the above formula II are shown below. However, the present invention is not limited by these.

It is preferable that the nematic liquid crystal composition has a specific resistance of 10 ¹³ Ωcm or more at 20 ° C. because a liquid crystal display device excellent in display quality without flickering can be obtained.

  The nematic liquid crystal composition preferably exhibits a nematic phase in the range of −20 ° C. to + 70 ° C. because it can be used in any environment.

  The nematic liquid crystal composition preferably has a viscosity at 20 ° C. of 20 mPa · s or less because it facilitates the production of a display body and provides a fast response speed.

  The nematic liquid crystal composition can be prepared by a conventional method.

  Moreover, a known chiral agent can be used in combination with the nematic liquid crystal composition. Examples of the chiral agent include compounds represented by the following formula III or IV.

  In addition, examples of the chiral agent include the following compounds.

  Further, for example, it has been proposed in JP-A-63-175095, JP-A-1-242542, JP-A-1-258635, JP-A-6-200251, and JP-A-2002-308833. Chiral agents can also be used.

These chiral agents can be used alone or in combination of two or more. In that case, a combination of different spiral twisting directions or a combination of the same twisting directions may be used. Further, for example, as proposed in Japanese Patent Application Laid-Open No. 7-258641, the temperature dependence of the turning ability of the cholesteric phase is positive, and the temperature dependence of the turning ability of the cholesteric phase is negative. Can be combined.
By changing the type and concentration of these chiral agents, the pitch can be adjusted within the range of 0.2 to 300 μm.

  The liquid crystal composition of the present invention has a benzotriazole-based, benzophenone-based, triazine-based, benzoate-based, oxanilide-based, cyanoacrylate-based for the purpose of imparting excellent stability to light and heat over a long period of time. UV absorbers such as hindered amine light stabilizers, phenol-based, phosphorus-based, sulfur-based antioxidants, and the like can also be added.

  In addition, a surfactant or the like can be added to the liquid crystal composition of the present invention in order to obtain an antistatic effect. Examples of the compound used for obtaining the antistatic effect include, for example, JP-A-59-4676, JP-A-4-36384, JP-A-4-180993, JP-A-11-212070, and JP-A-8-. Examples thereof include compounds proposed in Japanese Patent No. 337779, Japanese Patent Laid-Open No. 9-67577, Japanese Patent Laid-Open No. 2003-342580, and the like.

  The liquid crystal display device of the present invention includes a display body prepared by a liquid crystal dropping method using the above-described nematic liquid crystal composition, and specifically, provided on one of two plane parallel support plates. The nematic liquid crystal composition is dropped into a frame pattern formed by applying a sealant to the periphery of the image display area, and then the support plate and the other support plate are bonded together, and then the sealant is added. It is a liquid crystal display device provided with the display body produced by light or thermosetting.

  In the liquid crystal display device of the present invention, an integrated non-linear element for switching individual image elements can be provided on the support plate of the display body.

  Further, the support plate of the display body can have a diagonal of 10 inches or more and a thickness of less than 0.7 mm, and the distance between the parallel planes of the two support plates can be less than 5 μm.

  In addition, a color filter, an alignment film, and the like are formed on the support plate of the display body, similarly to the display body of a normal liquid crystal display device.

  Moreover, an optical film can be provided on the inner surface or the outer surface of the support plate of the display body.

  Further, a structure such as a protrusion or a slit may be formed on the inner surface of the support plate of the display body.

  The sealing agent is obtained from light or a thermosetting resin. As the thermosetting resin, those mainly composed of one-pack or two-pack epoxy resin are used. However, the thermosetting resin is not limited to these, and may be obtained by combining curing accelerators. . For example, Japanese Patent Application Laid-Open No. 2002-88228 proposes a sealing agent suitable for the liquid crystal dropping method, but such a sealing agent can also be used.

  In the liquid crystal display device of the present invention, a spacer material can be used to keep the cell gap uniform. As the spacer material, silica beads or plastic beads having a uniform particle size may be uniformly dispersed in the surface of the support plate. However, when post spacer technology in which protrusions are provided on the support plate in advance is applied, the image quality is excellent. Since a liquid crystal display device is obtained, it is preferable. The post spacer technique is described in detail in, for example, “Liquid Crystal Vol. 4 No. 1 2000 p. 43 to Hidefumi Yamashita etc.”.

  The liquid crystal display device of the present invention is not limited to the display mode and the driving method. For example, the dynamic scattering type (DS), the guest-host type (GH), the twisted nematic type (TN), and the super twisted nematic type. (STN), thin film transistor type (TFT), thin film diode type (TFD), ferroelectric liquid crystal type (FLC), antiferroelectric liquid crystal type (AFLC), polymer dispersed liquid crystal type (PD), vertical alignment (VA), Various display modes such as in-plane switching (IPS) and cholesteric nematic phase transition type are applied, and various drive methods such as static drive method, time-division drive method, active matrix drive method, and dual frequency drive method are applied. Is done.

  The liquid crystal display device of the present invention can be used for applications such as televisions, watches, calculators, measuring instruments, automotive instruments, copying machines, cameras, personal computers, word processors, other office automation equipment, portable personal computers, mobile phones and the like. In particular, it can be suitably used for a large-screen television monitor.

  Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. However, the present invention is not limited by the following examples.

<Examples 1-5 and Comparative Examples 1-2>
Liquid crystal compositions 1 to 5 (Examples 1 to 5) and liquid crystal compositions 6 to 7 (Comparative Examples 1 to 2) were respectively prepared according to the formulations shown in [Table 1] and [Table 2]. In addition, the liquid crystal composition 6 has an optical anisotropy (Δn) and a dielectric anisotropy (Δε) that are substantially the same as those of the liquid crystal compositions 1 and 2, and the liquid crystal composition 7 It is prepared without using the specific fluorine-containing compound in the present invention so that the value of Δε is substantially the same as that of the liquid crystal compositions 3 to 5.

  About the obtained liquid crystal compositions 1-7, NI point (at the time of temperature rising), optical anisotropy (Δn), dielectric anisotropy (Δε), and viscosity (η) were measured. In order to confirm the lower limit temperature of the nematic phase, each of the liquid crystal compositions 1 to 7 placed in a glass sample bottle was left in a freezer at −20 ° C., −30 ° C., and −40 ° C. for 2 weeks. The presence or absence was observed. The lowest temperature at which no change was observed was taken as the nematic phase lower limit temperature. These results are shown in [Table 3].

  In addition, for each of the obtained liquid crystal compositions 1 to 7, a sample obtained by adding cholesteryl nonanoate as a chiral agent in an amount that gives a pitch length of 75 μm, response speed, specific resistance, and voltage holding ratio (VHR) Were measured by the following methods. These results are shown in [Table 3].

(response speed)
In Examples 1 and 2 and Comparative Example 1, a TN cell having a cell thickness of 5 μm was used, and in Examples 3 to 5 and Comparative Example 2, a TN cell having a cell thickness of 4 μm was used. ) Was measured.

(Resistivity)
A sample was injected into a magnetic resistant stainless steel electrode cell, and an insulation resistance / microammeter was applied with 25 ° C. DC10V, and the specific resistance after 10 seconds was measured. The specific resistance was measured in the same manner for a sample irradiated with a mercury lamp (400 W, λmax 365 nm) at a distance of 20 cm for 30 minutes (after UV exposure) and a sample heated for 1 hour at 150 ° C. (after heating).

(Voltage holding ratio)
Japan Electronics Industry Association Standard EIAJ ED-2521A, P.I. Measurement was performed according to 35 measurement methods. The measurement was performed using a TN liquid crystal cell having a frame period of 60 Hz, a voltage of 5.0 V, an ON time of 60 μsec, a cell thickness of 5.0 μm, an electrode area of 1 cm ² , and a polyimide alignment film rubbed.

  From the results of [Table 3], the liquid crystal composition not containing the specific fluorine-containing compound in the present invention has a high viscosity and a low response speed, and is inferior in heat resistance and light resistance.

  On the other hand, the liquid crystal composition comprising the specific fluorine-containing compound in the present invention has a low viscosity, a wide nematic liquid crystal phase range, a high specific resistance and a voltage holding ratio, light resistance and heat resistance. It is clear that it has excellent properties and is suitable for the production of a display by a liquid crystal dropping method.

<Formulation example>
Furthermore, Table 4 to Table 27 show preferred blending examples of the nematic liquid crystal composition used in the liquid crystal display device of the present invention. However, in [Table 4] to [Table 27], CY is 1,4-cyclohexylene, PH is 1,4-phenylene, Pym is 5,2-pyrimidinediyl, Dio is 1,3-dioxane-5, 2-diyl, CE represents 4,1-cyclohexenylene, and Cn represents a straight-chain alkyl having n carbon atoms, and those in which the substitution position is not designated mean substitution at the 4-position.

Claims (10)

A display produced by a liquid crystal dropping method using a nematic liquid crystal composition containing a fluorine-containing compound represented by any one of the following formulas Ia to Ii and having 4 or more fluorine atoms and having positive dielectric anisotropy A liquid crystal display device comprising a body.

The fluorine-containing compound, a liquid crystal display device according to claim 1, wherein the at least one of X in the above formula Ia~Ii is selected from compounds which are _{-B-OCF 2 CF = CF 2} .   3. The liquid crystal display device according to claim 1, wherein the nematic liquid crystal composition contains 5% by mass or more of the fluorine-containing compound. The nematic liquid crystal composition comprises: a) 40 to 100% by mass of a liquid crystal component A comprising one or more compounds having a dielectric anisotropy greater than +1.5, including the fluorine-containing compound, and b) the following formula: A liquid crystal component B composed of one or more compounds represented by II having a dielectric anisotropy of −1.5 to +1.5, 0 to 40% by mass, and c) a dielectric smaller than −1.5 The liquid crystal display device according to any one of claims 1 to 3, further comprising 0 to 20% by mass of a liquid crystal component C composed of one or more compounds having anisotropy.

The liquid crystal display device according to claim 1, wherein the nematic liquid crystal composition has a specific resistance of 10 ¹³ Ωcm or more at 20 ° C.   The liquid crystal display device according to claim 1, wherein the nematic liquid crystal composition exhibits a nematic phase in a range of −20 ° C. to + 70 ° C. at least.   The liquid crystal display device according to claim 1, wherein the nematic liquid crystal composition has a viscosity at 20 ° C. of 20 mPa · s or less.   8. The liquid crystal display device according to claim 1, wherein an integrated non-linear element for switching each image element is provided on the support plate of the display body.   9. The support plate of the display body is 10 inches diagonal or more and less than 0.7 mm in thickness, and the distance between parallel planes of the two support plates is less than 5 μm. The liquid crystal display device according to any one of the above.   The liquid crystal display device according to claim 1, wherein an optical film is provided on an inner surface or an outer surface of the support plate of the display body.