TWI411664B - Reflective liquid crystal material formulation and reflective bistable display using the same - Google Patents

Abstract

The invention discloses a reflective liquid crystal material formulation, wherein a liquid crystal component of high dielectric anisotropy is employed to lower the driving voltage. By modulating the addition ratio of the high dielectric anisotropy components, reflective liquid crystal compositions of different colors can be driven by a single driving voltage. The invention also provides a reflective bistable display using the above formulation.

Description

Reflective liquid crystal material formulation and reflective bistable liquid crystal display

This invention relates to liquid crystal materials and their applications, and more particularly to a reflective liquid crystal material formulation that can be applied to single color, multi-color, or full color reflective bistable liquid crystal displays.

Liquid crystal display (LCD) has quite a variety of different types. Currently, the most common ones are TN (twisted nematic), STN (super twisted nematic), and iron. Different types of electric liquid crystal FLC (ferroelectric), cholesteric liquid crystal, etc.

Cholesteric liquid crystal (Cholesteric liquid crystal), also known as chiral nematic liquid crystal material, consists of a simple nematic liquid crystal and a special chiral dopant, which is originally arranged in a nematic arrangement. The liquid crystal material is affected by the palmitic additive, resulting in a stronger twist than TN or STN.

The cholesteric liquid crystal material itself has several different states, including a homeotropic state in which the liquid crystal molecules are parallel to the electric field in the electric field, and two stable states in which no external electric field is required: a planar state and a focal conic (focal conic) state. The bistable property of cholesteric liquid crystal materials, both steady states can be stably existed without an applied electric field, and the planar/focal conic does not require an external power supply except for the switching process. It can save display information; on the other hand, it can reflect external light source without backlight and polarizer, so it can save energy compared with the general display mode. The spontaneous reflected light characteristics can reflect light of different wavelengths, so it is not Color filters are required to achieve the needs of color displays. For a more detailed description of the driving and optical properties of cholesteric liquid crystals, reference is made to U.S. Patent No. 5,251,048 or US 5,695,682.

The pitch p of the cholesteric liquid crystal material is determined by the concentration of the palmitic additive (concentration, c) and its helical twisting power (HTP), and has the following relationship:

p=1/(HTP‧C)

Since the wavelength of the cholesteric liquid crystal reflection is determined by the pitch, the pitch of the formulation is again controlled by the helical torsion and concentration of the palm additive used in the formulation. Therefore, a cholesteric liquid crystal material that reflects light of different colors (wavelengths) can be obtained by adjusting the concentration of the palmitic additive. The higher the concentration of the palmitic additive, the shorter the reflection wavelength (blueish).

However, the higher the concentration of the palmitic additive, the higher the driving voltage required, so the cholesteric liquid crystal formulation will have different driving voltages. As shown in the graph of reflectance/drive voltage (RV curve) in Figure 1, different color cholesteric liquid crystal materials (in the case of RGB) have different driving voltages V _R , V _G and V _B (solid lines in the figure). In the planar state, the dotted line is the focal conic state). Therefore, in a full color display, three sets of driving voltages are required to drive red (R), green (G), and blue (B) cholesteric liquid crystal materials, respectively.

From the above, it is known that how to lower the driving voltage of the cholesteric liquid crystal material is an important subject in the technical field. Further, if the cholesteric liquid crystal material of different reflection wavelengths can be driven with a single set of driving voltages, the driving circuit can be greatly simplified.

The invention provides a reflective liquid crystal material formulation comprising at least two liquid crystal compositions of the following (A), (B) and (C):

(A) a first liquid crystal composition exhibiting a first reflection wavelength comprising: 100 parts by weight of the first liquid crystal host, comprising: 100% of the first monomer; and 3 to 10 parts by weight of the first palm additive;

(B) a second liquid crystal composition exhibiting a second reflection wavelength comprising: 100 parts by weight of the second liquid crystal host comprising: 60-80% of the first monomer; 20-40% of the second monomer; and 3-10 parts by weight Second palm additive.

(C) a third liquid crystal composition exhibiting a third reflection wavelength comprising: 100 parts by weight of the third liquid crystal host, comprising: 10-60% of the first monomer; 40-90% of the second monomer; and 3-10 parts by weight a third palm additive; wherein the first monomer comprises at least the monomer of formula (I):

The second monomer comprises at least the monomer of formula (III):

Each R ^{1 is} independently selected from a hydrogen atom, a linear or branched alkane or an alkyl group of 1 to 15 carbons, and one or more hydrogen atoms of the alkane or alkene may be substituted with a halogen or CN. One or more CH ₂ of a CF ₃ substituent, alkane or alkene may be substituted with an ether group (-O-), a thio group (-S-), a keto group (-C(=O)-) or an ester. (-C(=O)O-, -OC(=O)-); each A and B are independently selected from the group consisting of trans-1,4-hexanedialkyl substituents (trans-1,4- Cyclohexylene) or a benzene ring (1,4-phenylene), one or more of -CH ₂ - in the ring structure may be substituted with an oxygen atom or -NH-, and one or more =CH- may be substituted with an N atom, on the ring Any hydrogen atom may be substituted by a halogen or a CN, CF ₃ substituent; each Z ¹ and Z ² are independently selected from a single bond, an ether group (-O-), a thio group (-S-), a ketone. (-C(=O)-), ester group (-C(=O)O-, -OC(=O)-), -CF ₂ O-, -OCF ₂ -, -CH ₂ CH ₂ -, -CF ₂ CF ₂ -, cis or trans-C=C-double bond, or -C≡C- triple bond; n and m are each an integer of 0-3, and n+m is between 1 and 3; And, L is a hydrogen atom or a fluorine atom.

The present invention further provides a reflective bistable liquid crystal display comprising: a first electrode layer; a second electrode layer; and the reflective liquid crystal material of the present invention is disposed between the first electrode layer and the second electrode layer Each of the liquid crystal compositions is isolated from each other, and the driving voltage difference of any two liquid crystal compositions is less than 4V.

The above and other objects, features and advantages of the present invention will become more <RTIgt;

The invention provides a reflective liquid crystal formulation with low driving voltage, wherein the liquid crystal material of different colors is adjusted, and the high dielectric anisotropy liquid crystal material is used to reduce the driving voltage, and the proportion of materials with different dielectric anisotropy is adjusted. The driving voltages of different color cholesteric liquid crystal formulations tend to be the same, as shown in Fig. 2.

The cholesteric liquid crystal material of the present invention has a reflection wavelength of about a range of visible light (380 nm to 800 nm) and can be applied to a display material of a single color or color. The pitch of the cholesteric liquid crystal material of the present invention is usually less than 1 um, which is between about 0.2 and 0.5 um. The cholesteric liquid crystal material used in the present invention will be described in detail below.

The liquid crystal materials used in the present invention can be mainly divided into two groups, namely, a first monomer having a relatively low dielectric anisotropy (Group I), and a second monomer having a relatively high dielectric anisotropy ( Group II). In one embodiment, the dielectric anisotropy of the first monomer is, for example, less than 20, and the dielectric anisotropy of the second monomer is, for example, greater than or equal to 20. In another embodiment, the dielectric anisotropy of the first monomer is, for example, less than 15, and the dielectric anisotropy of the second monomer is, for example, greater than or equal to 15. In other words, as long as the two monomer groups have relatively high dielectric anisotropy.

The first monomer comprises at least a monomer of formula (I), and optionally comprises a monomer of formula (II):

Wherein R ¹ is selected from a hydrogen atom, a linear or branched alkane or an alkene of 1 to 15 carbons, and one or more hydrogen atoms of the alkane or alkene may be substituted with a halogen or a CN or CF ₃ substituent. , one or more CH _{2 of} alkane or alkene may be substituted with an ether group (-O-), a thio group (-S-), a keto group (-C(=O)-) or an ester group (-C) (=O)O-, -OC(=O)-); each A and B are independent, and are selected from trans-1,4-cyclohexylene or benzene. 1,4-phenylene, one or more of -CH ₂ - in the ring structure may be substituted with an oxygen atom or -NH-, and one or more =CH- may be substituted with an N atom, and any hydrogen atom on the ring may be substituted. Substituted by a halogen or a CN, CF ₃ substituent; each Z ¹ and Z ² are independently selected from a single bond, an ether group (-O-), a thio group (-S-), a keto group (-C) (=O)-), ester group (-C(=O)O-, -OC(=O)-), -CF ₂ O-, -OCF ₂ -, -CH ₂ CH ₂ -, -CF ₂ CF ₂ -, cis or trans -C=C-double bond, or -C≡C- triple bond; and n and m are each an integer of 0-3, and n+m is between 1 and 3.

The first monomer may further comprise a monomer of the following formula (II) as needed:

In formula (II), R ¹ , A, B, Z ¹ , Z ² , n, m are as defined above, and R ² is selected from a hydrogen atom, a linear or branched alkane of 1 to 15 carbons. Or one or more hydrogen atoms of the alkene, alkane or alkene may be substituted with a halogen, a CF ₃ substituent, and one or more CH _{2 of the} alkane or alkene may be substituted with an ether group (-O-), Sulfur (-S-), keto (-C(=O)-) or ester (-C(=O)O-, -OC(=O)-).

The structure of formula (II) is such that the CN group at the end of the molecule of formula (I) is substituted with R ² and has a relatively weak dielectric anisotropy relative to formula (I). In general, the dielectric anisotropy of the monomer of formula (I) is in the range of from 5 to 20, and the dielectric anisotropy of the monomer of formula (II) is in the range of from -5 to +5. The monomer of formula (II) is mainly used in the liquid crystal formulation to adjust the temperature range of the liquid crystal phase and reduce the overall viscosity of the liquid crystal formulation, and may be added to the first monomer as needed, or not added at all.

The second monomer comprises at least a monomer of formula (III), and optionally comprises a monomer of formula (IV):

R ¹ is selected from a hydrogen atom, a linear or branched alkane or an alkene of 1 to 15 carbons, and one or more hydrogen atoms of an alkane or an alkene may be substituted with a halogen or a CN, CF ₃ substituent. One or more CH _{2 of} alkane or alkene may be substituted with an ether group (-O-), a thio group (-S-), a keto group (-C(=O)-) or an ester group (-C ( =O)O-, -OC(=O)-); each A and B are each independently selected from a trans-1,4-cyclohexylene or a benzene ring. (1,4-phenylene), one or more of -CH ₂ - in the ring structure may be substituted with an oxygen atom or -NH-, and one or more =CH- may be substituted with an N atom, and any hydrogen atom on the ring may be Halogen or CN, CF ₃ substituents are substituted; each Z ¹ and Z ² are independently selected from a single bond, an ether group (-O-), a thio group (-S-), a keto group (-C ( =O)-), ester group (-C(=O)O-, -OC(=O)-), -CF ₂ O-, -OCF ₂ -, -CH ₂ CH ₂ -, -CF ₂ CF ₂ -, cis or trans-C=C-double bond, or -C≡C- triple bond; n and m are each an integer of 0-3, and n+m is between 1 and 3; and, L is hydrogen Atom or fluorine atom.

The molecular structure of the liquid crystal material of the formula (III) is one or two F atoms added to the head benzene ring of the formula (I), and has a high dielectric anisotropy with respect to the formula (I). In general, the dielectric anisotropy of the monomer of the formula (III) is between about 15 and 50, which can improve the dielectric anisotropy of the liquid crystal formulation and can effectively reduce the driving voltage of the liquid crystal.

The second monomer may further comprise a monomer of the following formula (IV) as needed:

Wherein R ¹ , A, B, Z ¹ , Z ² , n, m have the same meanings as defined above, X is a fluorine atom, CF ₃ or OCF ₃ , and L ¹ and L ² are each independently a hydrogen atom or a fluorine atom.

The molecular structure of the liquid crystal material of the formula (IV) is such that the CN substituent on the head benzene ring of the formula (III) is changed to an X substituent such as an F atom, CF ₃ or OCF ₃ . The dielectric anisotropy of the material of formula (IV) is relatively lower than that of formula (III), and is usually in the range of 5 to 20. The monomer of formula (IV) is less used in cholesteric liquid crystal materials, but some special requirements can adjust some properties of the formulation through the use of this type of liquid crystal material, for example, can be used to adjust the overall viscosity of the formulation and improve the driving time.

The liquid crystal composition of the present invention includes a palmitic additive in addition to the above liquid crystal monomer, and several palmitic additives are listed below, but the present invention is not limited thereto. Formulas (V) to (VIII) are the chemical structures of four commercially available palmitic additives:

Other palmitic additives that may be used include US6217792; V. Vill, F. Fischer, and J. Thiem, Zeitschrift Fur Naturfoschung A. , Journal of Physical Science, 43a (12), 1119-1125 (1988); GB 2328207; US7052743 The palmitic additive disclosed in US Pat. No. 7,150,900 B2, such as formula (IX) to formula (XI), has a greater helical twisting force than the foregoing.

Wherein each R is independently selected from a hydrogen atom, a linear or branched alkane of 1 to 15 carbons or an alkene, and one or more hydrogen atoms of the alkane or alkene may be substituted with a halogen or CN. One or more CH ₂ of a CF ₃ substituent, alkane or an alkene may be substituted with an ether group (-O-), a thio group (-S-), a keto group (-C(=O)-) or Ester group (-C(=O)O-, -OC(=O)-); each A and B are independent, and are trans-1,4-cyclohexylene substituents (trans-1,4-cyclohexylene) Or a benzene ring (1,4-phenylene), one or more of -CH ₂ - in the ring structure may be substituted with an oxygen atom or -NH-, and one or more =CH- may be substituted with an N atom, optionally on the ring The hydrogen atom may also be substituted by a halogen or a CN, CF ₃ substituent; each Z is independently a single bond structure, an ether group (-O-), a thio group (-S-), a keto group (-C ( =O)-), ester group (-C(=O)O-, -OC(=O)-), -CF ₂ O-, -OCF ₂ -, -CH ₂ CH ₂ -, -CF ₂ CF ₂ -, cis or trans-C=C-double bond, or -C≡C-triple bond structure; each n is independently, an integer of 1 or 2.

The reflective liquid crystal material of the present invention uses a second dielectric of high dielectric anisotropy to reduce the driving voltage, and through a combination of different ratios of the first monomer and the second monomer, a single driving voltage can be used to drive several different A liquid crystal combination of colors. Hereinafter, the composition of the present invention will be described by taking a full-color liquid crystal display as an example.

The full color reflective liquid crystal material formula of the invention comprises:

(A) a first liquid crystal composition exhibiting a first reflection wavelength (such as red light) comprising: 100 parts by weight of the first liquid crystal host, comprising: 100% of the first monomer; and 3 to 10 parts by weight of the first palm additive.

(B) a second liquid crystal composition exhibiting a second reflection wavelength (such as green light) comprising: 100 parts by weight of the second liquid crystal host, comprising: 60-80% of the first monomer; 20-40% of the second monomer; 3-10 parts by weight of the second palm additive.

(C) a third liquid crystal composition exhibiting a third reflection wavelength (such as blue light) comprising: 100 parts by weight of the third liquid crystal host, comprising: 10-60% of the first monomer; and 40-90% of the second monomer; - 10 parts by weight of a third palm additive.

As can be seen from Fig. 1, the driving voltage V _B > V _G &_gt; V _R . In order to reduce the driving voltage, a partial proportion (20-40%) of a high dielectric anisotropy second monomer is added to the second (green) liquid crystal host, and in the third (blue) liquid crystal host A higher proportion (40-90%) of the high dielectric anisotropy second monomer is added so that the cholesteric liquid crystal materials of the respective colors have the same or similar driving voltages. In one embodiment, the dielectric anisotropy of the first (red) liquid crystal body is less than 20 (for example, about 15 to 18), so the second monomer is preferably added to the second (green) liquid crystal. The dielectric anisotropy of the main body is controlled between about 20 and 25, and the dielectric anisotropy of the third (blue) liquid crystal main body is controlled to be between about 30 and 45, so that two or more types can be obtained. The driving voltage difference of the color liquid crystal material is less than 4V. More preferably, the driving voltage difference is less than 3V or even less than 1V.

It should be noted that the first monomer and the second monomer contained in the foregoing liquid crystal compositions (A), (B), and (C) may be the same or different, and the first, second, and third palm additives described above. The materials of the above formula (V) to formula (XI), or other known palmitic additives, may be the same or different.

Although the above formula is described by taking a full-color liquid crystal material formulation as an example, it should be understood that the present invention can also select only two liquid crystal materials such as liquid crystal compositions (A) and (B), (A) and ( C), or (B) and (C) are used as color liquid crystal displays, as long as the reflection wavelength difference between any two compositions is greater than 50 nm. Alternatively, it can also be applied to a monochrome (black and white contrast) liquid crystal display. The embodiment in which the above liquid crystal material is applied to a display will be further explained below.

The reflective bistable liquid crystal display of the present invention comprises at least two electrode layers, and the aforementioned reflective liquid crystal material formulation, disposed between the two electrode layers, wherein each liquid crystal composition is isolated from each other, and any two liquid crystals are composed of The drive voltage difference is less than 4V.

In one embodiment, the reflective liquid crystal material formulation of the present invention is applied to a multi-layer stacked color display, as shown in FIG. 3, which includes a three-layer stacked light modulating layer 110, 120, 130. Each of the R, G, and B cholesteric liquid crystal compositions, such as the aforementioned liquid crystal compositions (A), (B), and (C). Each of the light regulating layers is disposed between the two transparent electrodes 101 for controlling the cholesteric liquid crystal in the light regulating layer to be a Planar state or a Focal Conic State. The transparent electrode 101 is, for example, indium tin oxide (ITO) or indium zinc oxide (IZO).

The composition of the present invention can be directly coated on a transparent electrode as a light regulating layer, or can be coated after forming a mixed solution with a polymer monomer, and polymerizing the polymer monomer by heat or illumination, as the polymerization process The solubility between the monomer and the liquid crystal is lowered to cause phase separation. Finally, the liquid crystal is uniformly dispersed in the polymer in the form of droplets, and becomes a polymer dispersed cholesteric liquid crystal (PDChLC).

The substrate 100 may be a rigid substrate such as glass or quartz, but may also be a flexible substrate for use in a flexible display device. The polymer materials that can be used as the flexible substrate include: polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polyamide, and polyamide. Polymethylmethacrylate, polycarbonate, polyurethane, and the like. A light absorbing layer 500 is further disposed under the substrate 100.

In another embodiment, the reflective liquid crystal material formulation of the present invention is applied to a single layer color display. As shown in FIG. 4, the device includes at least one substrate 200 having a lower electrode layer 201. The lower electrode layer 201 has an isolation structure formed of a spacer 202 (for example, a polymer). The cholesteric liquid crystal compositions 210, 220, and 230 of the present invention, R, G, and B, can be applied to the isolated structure formed by the spacers 202 by inkjet or vacuum injection. An upper electrode layer 301 and an upper substrate 300 are further disposed on the spacer 202. Similarly, a light absorbing layer 500 is also disposed under the lower substrate 200.

In still another embodiment, the reflective liquid crystal material formulation of the present invention is applied to a monochrome (black and white contrast) display, as shown in FIG. 5, the device includes upper and lower substrates 200, 300, and a layer of polymer dispersed cholesteric liquid crystal. 400 is disposed between the upper electrode layer 301 and the lower electrode layer 201. A light absorbing layer 500 is disposed under the lower substrate 200. In the polymer-dispersed cholesteric liquid crystal 400, the cholesteric liquid crystals 420R, 420G, and 420B containing three colors of R, G, and B are uniformly dispersed in a polymer matrix 410 such as an acrylic resin or an epoxy resin. The three color cholesteric liquid crystals 420R, 420G, and 420B can be simultaneously operated by using the upper and lower electrode layers to generate a group voltage difference, so that a black-and-white contrast display device can be achieved.

Although the above three reflective bistable liquid crystal displays are listed above, the application of the present invention is not limited thereto. For the production of the reflective bistable liquid crystal display, reference is made to US Pat. No. 7,382,424, US Pat. No. 7,119,859, US Pat. No. 6,570,633, US Pat. No. 6,563,323, US Pat. US20060119782.

The reflective bistable liquid crystal display of the invention can be applied to various electronic devices, such as mobile phones, digital cameras, personal data assistants (PDAs), notebook computers, desktop computers, televisions, car displays, or portable devices. DVD player, etc.

In order to further illustrate the embodiments of the present invention, the following examples are given. Unless otherwise stated, the %s described below are all % by weight.

[Preparation example]

The several formulations mentioned in the examples and comparative examples are:

1) BL087, purchased from Merck GmbH, has a dielectric anisotropy of about 17.

2) The base formula A of the first monomer, selected from the materials of the formula (I) and the formula (II), the composition of which is as follows:

3) The base formula X of the second monomer, selected from the materials of formula (III), the composition of which is as follows:

4) The base formula Y of the second monomer, selected from the materials of formula (III), the composition of which is as follows:

The palmitic additive uses a palmitic additive (Z) of the formula (IX), the chemical structure of which is as follows:

The preparation of the nematic liquid crystal material and the cholesteric liquid crystal material is carried out by weighing all the components in proportion and mixing them, and heating the mixture to a clearing point temperature (Tc), which is obtained after cooling.

Its various photoelectric quality tests use LCAS (LC-Vision products, measuring dielectric anisotropy), UV-Vis spectrometer (measuring material reflection spectrum) and DMS-803 (Autronic Melchers products) according to different properties. , measuring the reflection spectrum of the liquid crystal panel and the photoelectric characteristics such as RV curve).

[Comparative Example 1]

The formulation of Comparative Example 1 is formulated using the base formulation A of the first monomer and the palmitic additive (Z) to obtain a set of colored cholesteric liquid crystal formula combinations, the ratio of which is prepared and the optical/electrical properties of the cholesteric liquid crystal material are as follows: Show:

As can be seen from the above table, the driving voltage gradually increases with the addition of the palm additive, and the difference in the color liquid crystal liquid crystal formula is about 4 to 5 V, so three different driving voltages are required.

[Example 1]

Example 1 uses the base formulation A of the first monomer in combination with the formulation X of the second monomer, and also obtains a set of colored cholesteric liquid crystal formula combinations. The optical/electrical properties of the formulation ratio and the cholesteric liquid crystal material are as follows:

It can be seen from the above table that after adding the formula X of the second monomer in different proportions, the driving voltage can be lowered, and the driving voltage difference of the red, blue and green cholesterol liquid crystal formulations is <1V, and only one driving voltage can be controlled at the same time. three colors.

[Comparative Example 2]

The formulation of Comparative Example 2 was prepared by using commercially available BL087 and a palmitic additive to obtain a set of colored cholesteric liquid crystal formula combinations. The formulation ratio and the optical/electrical properties of the cholesteric liquid crystal material are shown in the following table:

The result of Comparative Example 2 was similar to Comparative Example 1, and the driving voltage gradually increased with the addition of the palmitic additive, so different color cholesteric liquid crystal formulations required different driving voltages.

[Example 2]

The formulation combination of Example 2 was matched with the commercially available BL087 and the second monomer formulation X, and a set of colored cholesteric liquid crystal formula combinations were also obtained. The optical/electrical properties of the formulated ratio and the cholesteric liquid crystal material are shown in the following table:

The result of Example 2 is similar to that of Embodiment 1, and the driving voltage difference of the red, blue, and green cholesterol liquid crystal formulations is <1 V, and only one set of driving voltages is required to simultaneously control the three colors.

[Example 3]

The formulation combination of Example 3 is matched with the commercially available BL087 and the second monomer formulation Y to obtain another set of colored cholesteric liquid crystal formula combinations. The optical/electrical properties of the prepared ratio and the cholesteric liquid crystal material are shown in the following table. :

Similarly, Example 3 also obtained a red, blue, and green cholesterol liquid crystal formulation having a driving voltage difference of <1.

[Embodiment 4]

Two liquid crystal cells (each containing two transparent glass substrates and transparent electrodes) were taken, and the red and blue liquid crystal materials in the formulation example 3 were respectively infused, and the respective independent spectra were as shown in FIG.

After overlapping the two liquid crystal cells, the two liquid crystal cells are synchronously driven, and the spectral changes of the following figures can be observed during the process of 25V to 30V, and it is obvious that the different liquid crystal liquid crystal materials have the same operating voltage.

While the invention has been described above in terms of several preferred embodiments, it is not intended to limit the scope of the present invention, and any one of ordinary skill in the art can make any changes without departing from the spirit and scope of the invention. And the scope of the present invention is defined by the scope of the appended claims.

100, 200, 300. . . Substrate

110, 120, 130. . . Light control layer

101. . . Transparent electrode

201. . . Lower electrode layer

301. . . Upper electrode layer

210, 220, 230. . . Cholesteric liquid crystal composition of the present invention

202. . . Spacer

400. . . Polymer dispersed cholesteric liquid crystal

410. . . Polymer matrix

420R. . . Red cholesterol liquid crystal

420G. . . Green cholesterol liquid crystal

420B. . . Blue cholesterol liquid crystal

500. . . Light absorbing layer

Figure 1 is a schematic diagram of the reflectance/drive voltage of a conventional reflective liquid crystal material formulation.

2 is a schematic view showing the reflectance/drive voltage of a reflective liquid crystal material formulation according to an embodiment of the present invention.

3-5 are schematic cross-sectional views showing a reflective bistable liquid crystal display according to an embodiment of the present invention.

Figure 6 is an independent spectrum of the red and blue liquid crystal materials in Example 3.

Fig. 7 is a spectrum diagram of the red and blue liquid crystal materials in the synchronous driving example 3.

Claims (19)

A reflective liquid crystal material formulation comprising at least two liquid crystal compositions of the following (A), (B), and (C): (A) a first liquid crystal composition exhibiting a first reflection wavelength, comprising: 100 parts by weight of the first liquid crystal host , comprising: 100% of the first monomer; and 3-10 parts by weight of the first palm additive; (B) the second liquid crystal composition exhibiting a second reflection wavelength comprising: 100 parts by weight of the second liquid crystal host, comprising: 60- 80% of the first monomer; 20-40% of the second monomer; and 3-10 parts by weight of the second palm additive. (C) a third liquid crystal composition exhibiting a third reflection wavelength comprising: 100 parts by weight of the third liquid crystal host, comprising: 10-60% of the first monomer; 40-90% of the second monomer; and 3-10 parts by weight a third palm additive; wherein the first monomer comprises at least a monomer of formula (I): The second monomer comprises at least a monomer of formula (III): Each R ^{1 is} independently selected from a hydrogen atom, a linear or branched alkane or an alkyl group of 1 to 15 carbons, and one or more hydrogen atoms of the alkane or alkene may be substituted with a halogen or CN. One or more CH ₂ of a CF ₃ substituent, alkane or alkene may be substituted with an ether group (-O-), a thio group (-S-), a keto group (-C(=O)-) or an ester. (-C(=O)O-, -OC(=O)-); each A and B are independently selected from the group consisting of trans-1,4-hexanedialkyl substituents (trans-1,4- Cyclohexylene) or a benzene ring (1,4-phenylene), one or more of -CH ₂ - in the ring structure may be substituted with an oxygen atom or -NH-, and one or more =CH- may be substituted with an N atom, on the ring Any hydrogen atom may be substituted by a halogen or a CN, CF ₃ substituent; each Z ¹ and Z ² are independently selected from a single bond, an ether group (-O-), a thio group (-S-), a ketone. (-C(=O)-), ester group (-C(=O)O-, -OC(=O)-), -CF ₂ O-, -OCF ₂ -, -CH ₂ CH ₂ -, -CF ₂ CF ₂ -, cis or trans-C=C-double bond, or -C≡C- triple bond; n and m are each an integer of 0-3, and n+m is between 1 and 3; And, L is a hydrogen atom or a fluorine atom. The reflective liquid crystal material formulation of claim 1, wherein the first liquid crystal body has a dielectric anisotropy of less than 20, and the second liquid crystal body has a dielectric anisotropy of about 20-25, the third liquid crystal. The dielectric anisotropy of the subject is about 30-45. The reflective liquid crystal material formulation of claim 1, wherein a difference between the first wavelength, the second wavelength, and the third wavelength is greater than 50 nm. The reflective liquid crystal material formulation of claim 1, wherein the first reflection wavelength is red light, the second reflection wavelength is green light, and the third reflection wavelength is blue light. The reflective liquid crystal material formulation of claim 4, comprising (A) a first liquid crystal composition and (B) a second liquid crystal composition. The reflective liquid crystal material formulation of claim 4, comprising (A) a first liquid crystal composition and (C) a third liquid crystal composition. The reflective liquid crystal material formulation of claim 4, comprising (B) a second liquid crystal composition and (C) a third liquid crystal composition. The reflective liquid crystal material formulation of claim 4, comprising (A) a first liquid crystal composition, (B) a second liquid crystal composition, and (C) a third liquid crystal composition. The reflective liquid crystal material formulation according to claim 1, wherein the first liquid crystal composition (A), the second liquid crystal composition (B), and the third liquid crystal composition (C) are dispersed in a polymer. The reflective liquid crystal material formulation according to any one of claims 1 to 9, wherein the first monomer further comprises a monomer of the formula (II): Wherein R ¹ , A, B, Z ¹ , Z ² , n, m are as defined above, and R ² is selected from a hydrogen atom, a linear or branched alkane or an alkene of 1 to 15 carbons, an alkane or One or more hydrogen atoms of the olefin may be substituted with a halogen, a CF ₃ substituent, and one or more CH _{2 of the} alkane or olefin may be substituted with an ether group (-O-) or a thio group (-S- ) a keto group (-C(=O)-) or an ester group (-C(=O)O-, -OC(=O)-). The reflective liquid crystal material formulation according to any one of claims 1 to 9, wherein the second monomer further comprises a monomer of the formula (IV): Wherein R ¹ , A, B, Z ¹ , Z ² , n, m have the same meanings as defined above, X is a fluorine atom, CF ₃ or OCF ₃ , and L ¹ and L ² are each independently a hydrogen atom or a fluorine atom. The reflective liquid crystal material formulation according to any one of claims 1 to 9, wherein the first, second, and third palm additives are independent of each other, and are selected from the following formulas (V) to (XI); : Wherein each R is independently selected from a hydrogen atom, a linear or branched alkane of 1 to 15 carbons or an alkene, and one or more hydrogen atoms of the alkane or alkene may be substituted with a halogen or CN. One or more CH ₂ of a CF ₃ substituent, alkane or an alkene may be substituted with an ether group (-O-), a thio group (-S-), a keto group (-C(=O)-) or Ester group (-C(=O)O-, -OC(=O)-); each A and B are independent, and are trans-1,4-cyclohexylene substituents (trans-1,4-cyclohexylene) Or a benzene ring (1,4-phenylene), one or more of -CH ₂ - in the ring structure may be substituted with an oxygen atom or -NH-, and one or more =CH- may be substituted with an N atom, optionally on the ring The hydrogen atom may also be substituted by a halogen or a CN, CF ₃ substituent; each Z is independently a single bond structure, an ether group (-O-), a thio group (-S-), a keto group (-C ( =O)-), ester group (-C(=O)O-, -OC(=O)-), -CF ₂ O-, -OCF ₂ -, -CH ₂ CH ₂ -, -CF ₂ CF ₂ -, cis or trans-C=C-double bond, or -C≡C-triple bond structure; each n is independently, an integer of 1 or 2. A reflective bistable liquid crystal display comprising: a first electrode layer; a second electrode layer; and a reflective liquid crystal material formulation according to any one of claims 1-9, which is set in the first Between the electrode layer and the second electrode layer, wherein the liquid crystal compositions are isolated from each other, and the driving voltage difference of any two liquid crystal compositions is less than 4V. The reflective bistable liquid crystal display of claim 13, wherein the liquid crystal compositions are isolated from each other by spacers. The reflective bistable liquid crystal display of claim 13, further comprising at least one third electrode layer disposed between the first electrode layer and the second electrode layer to isolate the liquid crystal compositions. The reflective bistable liquid crystal display of claim 13, wherein the liquid crystal composition is dispersed in a polymer. The reflective bistable liquid crystal display of claim 13, wherein the reflective bistable liquid crystal display is a black and white contrast display. The reflective bistable liquid crystal display of claim 13, wherein the reflective bistable liquid crystal display is a color display. The reflective bistable liquid crystal display of claim 13, wherein the reflective bistable liquid crystal display is a full color display.