TW201321485A - Liquid crystal composition and liquid crystal display comprising the same - Google Patents

Abstract

The invention provides a liquid crystal composition and a liquid crystal display comprising the same. The Liquid crystal composition includes: a host liquid crystal material; and a doped guest material, wherein the doped guest material comprises a reactive monomer and an acrylate monomer.

Description

Liquid crystal display and liquid crystal display composed thereof

This invention relates to a liquid crystal composition, and more particularly to a liquid crystal display and a liquid crystal display thereof.

Liquid crystal display (LCD) has been applied to various personal computers, personal digital assistants (PDAs), mobile phones, and televisions due to its advantages of light weight, low power consumption, and no radiation.

In the liquid crystal display, according to the operation mode of the liquid crystal, it can be classified into a phase change, a twisted nematic (TN), an in-plane switching (IPS), and a vertical alignment type (VA). Since the TN type has a problem of narrow viewing angle, the VA type is developed, and the VA type can be further divided into a multi-domain vertical alignment (MVA) and an enhanced vertical alignment (EVA).

In recent years, the industry has proposed a polymer stabilized alignment (PSA) to improve the contrast of liquid crystal displays. It adds a reactive monomer (RM) to the liquid crystal material, and then by light or The heat polymerizes the reactive monomer to improve the alignment direction of the liquid crystal.

The present invention provides a liquid crystal composition in which an acrylic monomer is added, the pre-tilt of the liquid crystal molecules is increased by the acrylic monomer, and the threshold voltage ( _Vth ) of the liquid crystal display is lowered.

The present invention provides a liquid crystal composition comprising: a host liquid crystal host; and a guest dopant, wherein the guest dopant comprises a reactant monomer and at least one acrylic monomer.

The present invention further provides a liquid crystal display comprising: a first substrate and a second substrate, wherein the first substrate is opposite to the second substrate; and a liquid crystal composition formed on the first substrate and the second Between the substrates, wherein the liquid crystal composition comprises a host liquid crystal host; and a guest dopant, wherein the guest dopant comprises a reactant monomer and at least one acrylic monomer.

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

The present invention provides a liquid crystal material composition comprising a host liquid crystal host; and a guest dopant, wherein the guest dopant comprises a reactive monomer (RM) and at least one acrylic monomer The guest dopant accounts for 0.01 to 5.0% by weight of the liquid crystal composition, and the ratio of the reactant monomer to the acrylic monomer is about 1/9 to 9/1. It should be noted that the term "acrylic monomer" as used herein also refers to a monomer having an acrylate.

The above host liquid crystal material may be a Nematic, Smectic or Cholesteric liquid crystal material, such as a nematic liquid crystal material such as commercially available MLC6080, BL006 or ZLI4792, a smectic liquid crystal material. For example CS1031. A cholesteric liquid crystal material such as CB-15. It should be noted that, in addition to the above materials, the liquid crystal material as long as the liquid crystal phase can be produced is within the scope of the present invention.

The above reactant monomers have a polymerizable group including acrylate, methacrylate, vinyl, butadiene, ethylene. A vinyl ether, an epoxy, or a combination thereof.

The reactive monomer includes RM1 (1,1'-biphenyl-4,4'-diacrylate), RM257 (bis[acryloyloxy-(4-propxyl(1,4-phenyl benzoate))) or HDDA (hexane diol diacrylate).

The above acrylic monomers include 2-ethyltheoxyl acrylate, 1,6-hexanediol diacrylate, trimethylol propane triacrylate (trimethylol). Propane triacrylate), Pentaerythritol tetraacrylate or Dipentaerythritol Hexaacrylate.

In one embodiment, the liquid crystal composition is 99.5% by weight of MLC 6080 plus 0.25% by weight of RM257 and 0.25% by weight of 2-ethyltheoxyl acrylate.

In another embodiment, the liquid crystal composition is 98% by weight of MLC 6080 plus 1% by weight of RM257 and 1% by weight of 1,6-hexanediol diacrylate.

In yet another embodiment, the liquid crystal composition is 97.5 wt% of MLC 6080 plus 1.25 wt% RM257 and 1.25 wt% trimethylol propane triacrylate.

The liquid crystal composition of the present invention is preferably suitable for use in a VA type display, but is not limited thereto, and can be applied to other types of liquid crystal displays.

In addition, the present invention further includes a liquid crystal display 100. Referring to FIG. 1 , the first substrate 102 and the second substrate 202 are disposed opposite to each other; and the liquid crystal composition 150 is formed between the first substrate 102 and the second substrate 202 . Wherein the liquid crystal composition 150 comprises a host liquid crystal host 152; and a guest dopant 154, wherein the guest dopant 154 comprises a reactant monomer and at least one acrylic monomer. Further, the first electrode layer 104 is formed between the first substrate 102 and the liquid crystal composition 150, and the second electrode layer 204 is formed between the second substrate 202 and the liquid crystal composition 150.

2A-2C is a series of cross-sectional views showing the steps of the liquid crystal material of the liquid crystal composition to produce a pretilt angle. In FIG. 2A, a voltage is applied between the first electrode layer 104 and the second electrode layer 204 to first cause the liquid crystal host material 152 to have a specific orientation. The applied voltage causes the liquid crystal to have a tilt angle in a specific direction, so the voltage is again It can be called a liquid crystal tilt voltage.

Thereafter, referring to FIG. 2B, the first substrate 102 is irradiated with ultraviolet light 170 to help the guest dopant 154 continue the polymerization reaction to form a polymerized guest dopant 154a, wherein the ultraviolet light has a wavelength of 150-500 nm. It is preferably 250-450 nm, more preferably 300-400 nm.

Referring to Figure 2C, the host liquid crystal material 152 has a specific pretilt angle assisted by the polymerized guest dopant 154a.

Other additives such as an optically active compound, an antioxidant, a polymerization initiator, and the like may be included in the liquid crystal composition 150 of the present invention.

In order to impart a specific twist angle to the host liquid crystal material, an optically active compound may be added to the liquid crystal composition. Further, in order to allow the liquid crystal display to be operated at room temperature or high temperature for a long period of time, an antioxidant may be added to the liquid crystal composition.

In order to allow the polymerization to proceed rapidly, a polymerization initiator may be added to the liquid crystal composition, and a polymerization initiator such as 4-methoxyphenyl-2,4-bis(trichloromethyl)triazine (4-methoxyphenyl) may be added. -2,4-bis(trichloromethyl)triazine), 9,10-benzphenazine or benzophenone/Michler's ketone. In one embodiment, a commercially available photopolymerization initiator such as Irgacure 651 can be used.

It should be noted that the present invention can achieve the effect of lowering the threshold voltage (V _th ) of the liquid crystal display by adding an acrylic monomer to the liquid crystal composition, and the threshold voltage can be lowered by using a curing voltage. More. In addition, the experimental results show that the addition of an acrylic monomer to the liquid crystal composition can increase the pretilt angle of the host liquid crystal material, and when the curing voltage is matched, the pretilt angle can be increased more.

[Examples]

3A-3B is a graph showing the relationship between the threshold voltage ( _Vth ) and the transmittance of the liquid crystal display composed of the comparative example and the examples 1-3 , wherein the host liquid crystal material (host) accounts for 99.5% by weight of the liquid crystal composition. The guest dopant accounts for 0.5% by weight of the liquid crystal composition. Fig. 3A shows that no voltage is applied to the liquid crystal composition, i.e., no curing voltage is applied, and Fig. 3B shows that a voltage of 10 V is applied to the liquid crystal composition to assist in monomer curing.

As can be seen from Fig. 3A, the critical voltages of Examples 1-3 (adding a single acryl base, a double acryl base, and a triple acryl base, respectively) were lower than those of the comparative examples . In Figure 3B, Example 3 (adding three acryl groups) has the lowest threshold voltage.

3C-3D is a graph showing the relationship between the threshold voltage ( _Vth ) and the transmittance of the liquid crystal display composed of the comparative example and the examples 1-3 , wherein the host liquid crystal material (host) accounts for 97.5% by weight of the liquid crystal composition, and The guest dopant accounts for 2.5% by weight of the liquid crystal composition. Figure 3C shows that no voltage is applied to the liquid crystal composition, i.e., no curing voltage is applied, and Figure 3D shows that a voltage of 10 V is applied to the liquid crystal composition to aid in monomer curing.

As can be seen from Fig. 3C, the threshold voltages of Examples 1-2 (adding a single acryl base and a double acryl base) were lower than those of the comparative examples . In Figure 3D, Example 3 (adding three acryl groups) has the lowest threshold voltage.

Please refer to FIG. 3E, which shows the threshold voltage value of the 3A-3D graph at 10% transmittance. It can be seen from the figure that the guest dopant is applied under the condition of 0.5% by weight or 2.5% by weight. The voltage can lower the threshold voltage (V _th ) of the liquid crystal display.

Referring to Figure 3E, Example 3 (addition of three acryl bases) has the lowest threshold voltage under conditions of 0.5 V% of the guest dopant applying a 10 V polymerization voltage.

Referring again to FIG. 3E, under the condition that a polymerization voltage of 10 V is applied to 2.5 wt% of the guest dopant, the relationship of the threshold voltage is Example 3 < Example 2 < Example 1 , Example 3 (addition of three grams The force base also has the lowest threshold voltage, and this data shows that an increase in the number of acrylic groups can lower the threshold voltage of the host liquid crystal material.

In addition, please refer to Fig. 4, which shows the relationship between pretilt angle (θ), polymerization voltage and guest dopant ratio.

Example 3 (addition of three acryl bases) had the highest pretilt angle under the condition that 0.5% by weight of the guest dopant was applied with a polymerization voltage of 10 V.

Under the condition of applying a polymerization voltage of 10 V to 2.5% by weight of the guest dopant, the relationship between the pretilt angles is the same as in Example 3 > Example 2 > Example 1 , and Example 3 (adding three acryl groups) also has the highest Pretilt angle, this data shows that an increase in the number of acrylic groups can increase the pretilt angle of the host liquid crystal material, and application of a polymerization voltage can also increase the pretilt angle of the host liquid crystal material.

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. . . LCD Monitor

102. . . First substrate

104. . . First electrode layer

150. . . Liquid crystal composition

152. . . Main liquid crystal material

154. . . Guest dopant

154a. . . Polymerized guest dopant

170. . . Ultraviolet light

202. . . Second substrate

204. . . Second electrode layer

Fig. 1 is a cross-sectional view for explaining a liquid crystal display of the present invention.

2A-2C is a series of cross-sectional views illustrating the flow of the pre-tilt angle of the reactive monomer of the present invention to the host liquid crystal material.

3A-3D is a graph showing the relationship between the threshold voltage ( _Vth ) of the liquid crystal display and the transmittance to illustrate the effect of adding the acrylic force to the liquid crystal composition of the present invention.

Figure 3E is a graph of the relationship between the threshold voltage, the polymerization voltage, and the guest dopant ratio, which is used to illustrate the threshold voltage at 10% penetration of the 3A-3D graph.

Figure 4 is a graph showing the relationship between pretilt angle, polymerization voltage and guest dopant ratio, which is used to illustrate the relationship between the acrylic monomer and the pretilt angle of the host liquid crystal material.

100. . . LCD Monitor

102. . . First substrate

104. . . First electrode layer

150. . . Liquid crystal composition

152. . . Main liquid crystal material

154. . . Guest dopant

202. . . Second substrate

204. . . Second electrode layer

Claims (10)

A liquid crystal composition comprising: a host liquid crystal host; and a guest dopant, wherein the guest dopant comprises a reactant monomer and at least one acrylic monomer. The liquid crystal composition of claim 1, wherein the reactant monomer has a polymerizable group, wherein the polymerizable functional group comprises an acrylate or a methacrylate. ), vinyl, butadiene, vinyl ether, epoxy or a combination thereof. The liquid crystal composition according to claim 2, wherein the reactive monomer comprises RM1 (1,1'-biphenyl-4,4'-diacrylate), RM257 (bis[acryloyloxy-(4-propxyl(1) , 4-phenyl benzoate))) or HDDA (hexane diol diacrylate). The liquid crystal composition according to claim 1, wherein the acrylic monomer comprises 2-ethyltheoxyl acrylate and 1,6-hexanediol acrylate (1,6- Hexanediol diacrylate), trimethylol propane triacrylate, pentaerythritol tetraacrylate or Dipentaerythritol Hexaacrylate. The liquid crystal composition according to claim 1, wherein the guest dopant accounts for 0.01 to 5.0% by weight of the liquid crystal composition. The liquid crystal composition of claim 1, wherein the ratio of the reactant monomer to the acrylic monomer is about 1/9 to 9/1. A liquid crystal display comprising: a first substrate and a second substrate, wherein the first substrate is disposed opposite to the second substrate; and a liquid crystal composition is formed between the first substrate and the second substrate, Wherein the liquid crystal composition comprises a host liquid crystal host; and a guest dopant, wherein the guest dopant comprises a reactant monomer and at least one acrylic monomer. The liquid crystal display of claim 7, wherein the first substrate and the second substrate are a thin film transistor substrate and the other is a color filter substrate. The liquid crystal display of claim 7, wherein the reactant monomer has a polymerizable group, wherein the polymerizable functional group comprises an acrylate or a methacrylate. , vinyl, butadiene, vinyl ether, epoxy or a combination thereof. The liquid crystal display according to claim 7, wherein the acrylic monomer comprises 2-ethyltheoxyl acrylate and 1,6-hexanediol acrylate (1,6-hexanediol). Diacrylate), trimethylol propane triacrylate, pentaerythritol tetraacrylate or Dipentaerythritol Hexaacrylate.