JPS605631B2 - Nematic liquid crystal composition - Google Patents

Description

[Detailed description of the invention] The present invention relates to novel nematic liquid crystal compositions.

More specifically, the present invention relates to a nematic liquid crystal composition that is white, extremely stable, and has a wide temperature range. In recent years, advances in electronics and other technologies have created a demand for display materials that can be driven at low voltages and are inexpensive. Liquid crystals are currently seen as a promising display material that satisfies this requirement, and liquid crystals are already being used in some displays. Liquid crystals, which are considered harmful, are made of organic compounds, but while ordinary compounds undergo a phase change from solid to liquid to gas, liquid crystals do not directly change from solid to liquid, but instead have the properties of solid and liquid. Indicates the phase that it has.

Liquid crystals can be divided into smectic liquid crystals, nematic liquid crystals, and cholesteric liquid crystals depending on the molecular orientation of this phase.
The liquid crystal currently used as a display material is a nematic liquid crystal, and there are two types of display methods for display bodies using this nematic liquid crystal: a light scattering method and a field effect method.

The present invention was made regarding a nematic liquid crystal composition used in a field effect type display.

Although liquid crystals are very promising as display materials, conventional liquid crystal materials still have the following drawbacks and points for improvement.

1. Instability of liquid crystals due to being an organic compound. In particular, conventional liquid crystals are compounds having a Schiff base at the center of the molecule (hereinafter abbreviated as Schiff liquid crystals), and are therefore extremely sensitive to moisture, easily deteriorate, and difficult to handle. 2.A relatively stable liquid crystal is an azoxy compound-based liquid crystal (hereinafter abbreviated as azoxy liquid crystal), but since this azoxy liquid crystal absorbs light in the visible region, it has the disadvantage of being degraded by visible light such as ultraviolet rays.

In order to eliminate this drawback, it was considered to protect the display section with a colored filter, but this method had the drawback that the entire display section was colored in a specific color, making it dark and reducing the display ability. 3. As a liquid crystal that does not have the above disadvantages 1 and 2, there is a white and very stable liquid crystal of an ester compound (hereinafter abbreviated as ester liquid crystal), but the conventional ester liquid crystal has a very limited temperature range, There were restrictions on its use.

For example, a liquid crystal composition in which several types of liquid crystals represented by the general formula (R is a linear alkyl group) is mixed has been considered.

However, this liquid crystal composition had the disadvantage that the upper limit point at which it ceases to be a liquid crystal (hereinafter referred to as clear point, abbreviated as CP) is 5000 or less, which is too low.

Also, a liquid crystal composition was considered in which a liquid crystal represented by the general formula (R.R' means a linear alkyl group) was mixed with the above-mentioned Ester liquid crystal, but this liquid crystal composition also had a CP of 50q.
o or less, which was not satisfactory.

In order to increase the CP, an ester liquid crystal composition was considered in which a liquid crystal represented by the general formula (R.R' means a straight-chain alkyl group) was mixed with the ester liquid crystal.

Although it was possible to increase the CP using this method, a life test revealed that the ester bond at the end of the molecule deteriorated, causing disturbance in the molecular orientation, which is a fatal flaw for field-effect displays, and rendering it impossible to display. Ta.

Further, whereas azoxy liquid crystals and Schiff liquid crystals can maintain a supercooled state for a long time, conventional Estel liquid crystals cannot maintain a supercooled state for a long time.

For this reason, even if products were manufactured, it was difficult to use them in cold regions. The present invention solves not only the drawbacks mentioned in 1 and 2 above, but also the drawbacks mentioned in 3 above of the conventional Ester liquid crystal by mixing the seven types of Estel liquid crystals shown in Table 1. It is.

Table 1 shows the properties of the Estel liquid crystal used in the present invention.

Table 1 In the table, C, N, and 1 indicate a crystalline state, a nematic liquid crystal state, and an isotropic liquid state, respectively.

The same applies to the table below. Example 1 shows the components of the nematic liquid crystal composition of the present invention prepared using the compounds shown in Table 1, their proportions, and an example of their properties.

Example 1 As can be seen from Example 1, the mp of the liquid crystal composition of the present invention is several degrees lower than that of the conventional ester-based liquid crystal composition, and the CP is 5.
It can be seen that 000 is sufficiently secured.

In addition, in the supercooling test, crystallization did not occur for 1 hour at 100°. As described above, the liquid crystal composition of the present invention is superior in terms of temperature characteristics, stability, and display ability compared to conventional liquid crystals, and when made into a product, it can withstand use even in cold regions. It is possible to provide something.
A liquid crystal composition having such characteristics can be applied not only to the display parts of calculators, wristwatches, etc., but also to the display parts of various devices.

A prototype wristwatch was produced using the liquid crystal composition of the present invention, but there were no problems with respect to various aspects such as lifespan and contrast.

Claims (1)

[Claims] 1. A compound whose structural formula is ▲There are mathematical formulas, chemical formulas, tables, etc.▼ ▲There are mathematical formulas, chemical formulas, tables, etc.▼ Compounds whose structural formula is represented by ▲There are mathematical formulas, chemical formulas, tables, etc.▼ Compounds represented by ▲ There are mathematical formulas, chemical formulas, tables, etc.▼ Compounds represented by ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ Compounds represented by ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ Compounds represented by and ▲There are mathematical formulas, chemical formulas, tables, etc.▼ A nematic liquid crystal composition characterized by consisting of a compound represented by the following.