TW201930562A - Microcapsule liquid crystal display device and its application having characteristics of low driving voltage, high reflectivity and contrast and flexible display - Google Patents

Abstract

The invention provides a microcapsule liquid crystal display device and an application thereof, the microcapsule liquid crystal display device comprising at least two flexible conductive layers, and a microcapsule mixed layer sandwiched between at least two flexible conductive layers, wherein at least one of the at least two flexible conductive layers is a transparent flexible conductive layer. When the at least two flexible conductive layers are both transparent flexible conductive layers, any one of the flexible conductive layers is provided with a light absorbing layer on the side close to the microcapsule mixed layer; and when only one flexible conductive layer is a transparent flexible conductive layer, the non-transparent flexible conductive layer is provided with a light absorbing layer on the side close to the microcapsule mixed layer; the microcapsule mixed layer is composed of a liquid crystal microcapsule and a binder for binding the liquid crystal microcapsule. The liquid crystal microcapsules are encapsulated with one or more cholesteric phase liquid crystal materials selected from compounds of a general formula (I). The microcapsule liquid crystal display device provided by the invention has the characteristics of low driving voltage, high reflectivity and contrast, and flexible display, and is suitable for the field of electronic paper.

Description

Microcapsule liquid crystal display device and application thereof

The invention relates to the field of liquid crystal display devices, in particular to a microcapsule liquid crystal display device and its application in the field of electronic paper.

With the invention of the Liquid Crystal Display (LCD) in the early 1970s, information display technology began a revolution. Because LCD is a lightweight, low-power flat-panel display, the visual readout function provided by it meets the requirements of the small size, light weight, and battery of portable electronic devices, so this display technology makes a new category of portable and other portable There are a lot of style products. Commercially, LCDs were first widely used as digital readers on watches, then in instruments, and later in laptops, personal data assistants, and many other digital devices. Today, LCD technology has almost replaced cathode-ray tubes in the fields of televisions and personal computers (PCs).

Almost all commercial LCD displays manufactured and sold today are on glass substrates. Glass has many features suitable for LCD manufacturing. Glass can be processed at high temperatures. It is rigid and relatively strong. Glass is suitable for batch processing methods used in large-scale manufacturing. During processing, the surface of the glass becomes extremely smooth and uniform over a wide range, and the glass has the required Optical properties, such as high transparency. However, in many applications, glass is far from an ideal base material. The glass substrate does not become very flexible and not very strong, it is not suitable for web manufacturing and is easily broken. As a result, much effort is being made worldwide to develop displays on more flexible and sturdy substrates that are not only compatible with three-dimensional formulations, but also repeatedly flexed. It is desirable that the display has the flexibility of a thin plastic sheet, paper, or fabric so that it can hang, roll, or fold like paper or cloth.

A microcapsule display is a typical flexible liquid crystal display. The microcapsule-based technology is used to confine liquid crystals that are easy to flow to a specific space to form microencapsulated liquid crystals. The microencapsulated liquid crystals are dispersed in a dispersant and applied to On the flexible display panel, to achieve flexible display, it has the advantages of high brightness, high contrast, power saving, memory, wide viewing angle, no flicker, etc. Its biggest feature is that it has bi-stable characteristics, when the power is cut off The panel can continuously display the picture, so it saves considerable power.

Smectic A-phase liquid crystal material is a common material used to prepare microcapsule liquid crystals. It has two steady states, vertical and focal cone. When it is in the vertical state, the incident light can be transmitted almost without being scattered. When in the focal cone state, almost all incident light is scattered, so it has very good optical characteristics. Chinese patent CN101415280 and US patent US2003112204 both use high-frequency and low-frequency voltages to switch between the two steady states: when low-frequency driving, the liquid crystal array is disturbed by ions to achieve a fog state (white background); when high-frequency driving, the ion effect Weakened, the liquid crystal is arranged vertically on the surface of the substrate to achieve a transparent state, and can display a background black (black characters). The disadvantage is that the required driving voltage is high (generally greater than 60V), the contrast is not high (about 2.0), and the response is slow. Higher driving voltage will undoubtedly increase the difficulty and cost of designing and manufacturing the driving chip.

In addition, the prior art also uses cholesteric liquid crystals to prepare liquid crystal microcapsules, because cholesteric liquid crystals have several different states, including the vertical state of liquid crystal molecules parallel to the electric field under an electric field, and two stable states that do not require an external electric field. State: plane state and focal cone state. The cholesteric liquid crystal material has bistable characteristics. Both stable states can be stable without an external electric field, and show a bright state or a dark state, respectively. Except for the switching process, no external power is required to save the display information. On the other hand, cholesteric liquid crystal materials have the characteristic of reflecting external light without the need for a backlight and a polarizer, so they are more energy efficient than ordinary displays. However, almost all existing liquid crystal microcapsules are made of a cholesteric liquid crystal material with positive dielectric anisotropy, and there are still some disadvantages, such as the driving voltage for switching the cholesteric liquid crystal to a planar state is still high. It takes about 30V. At the same time, the liquid crystal molecules cannot completely return to the planar state, which affects the contrast of the device.

Object of the invention: The object of the present invention is to provide a microcapsule liquid crystal display device, which has the characteristics of low driving voltage, high reflectance and high contrast.

Technical solution: In order to achieve the above object, the present invention provides a microcapsule liquid crystal display device, the microcapsule liquid crystal display device includes at least two flexible conductive layers, and a microchip sandwiched between the at least two flexible conductive layers. Capsule mixed layer, at least one of the at least two flexible conductive layers is a transparent flexible conductive layer, and when the at least two flexible conductive layers are both transparent flexible conductive layers, any one of the flexible conductive layers is close to the micro conductive layer A light absorbing layer is provided on one side of the capsule mixing layer. When only one flexible conductive layer is a transparent flexible conductive layer, the non-transparent flexible conductive layer is provided with a light absorbing layer on the side close to the microcapsule mixing layer. The mixed layer is composed of liquid crystal microcapsules and an adhesive bonding the liquid crystal microcapsules, and the liquid crystal microcapsules are wrapped with a cholesteric liquid crystal material containing one or more compounds selected from the general formula I : I, wherein R ₁ and R ₂ each independently represent -H, -F, a straight or branched alkyl or alkoxy group containing 1 to 12 carbon atoms, a straight or Branched alkenyl or alkenyloxy, -O (CH ₂ ) _p O (CH ₂ ) _q CH ₃ , , or Wherein one or more of the linear or branched alkyl or alkoxy group and the linear or branched alkenyl or alkenyloxy group -H may be substituted with -F; Z ₁ and Z ₂ each Independently represents a single bond, -CO-O-, -O-CO-, -CH ₂ O-, -OCH _2- , -CH ₂ CH _2- , -CH = CH- or -C≡C-; L ₁ And L ₂ each independently represent -F, -Cl, -CN, or -NCS; And ring Independent representation or ,among them, One or more of -CH ₂ -may be replaced by -O-, One or more of -H may be substituted by halogen; n1 represents 1, 2 or 3, and when n1 is 2 or 3, the ring It can be the same or different, and Z ₁ can be the same or different; n2 represents 0 or 1; p represents an integer from 1 to 12; q represents an integer from 0 to 12.

It should be noted that the present invention is not limited to containing only two flexible conductive layers. For example, in order to realize a multi-region display of a liquid crystal display panel, two or more flexible conductive layers may be provided, and if the device composition in each region is consistent with the technology of the present invention If the solutions are consistent, such a device structure should also be included in the inventive concept of the present invention.

In some embodiments of the invention, preferably, R ₁ and R ₂ each independently represent -H, -F, a straight or branched chain alkyl or alkoxy group containing 1-8 carbon atoms, containing 2- A linear or branched alkenyl or alkenyloxy group of 8 carbon atoms, -O (CH ₂ ) _p O (CH ₂ ) _q CH ₃ .

In some embodiments of the present invention, more preferably, each of R ₁ and R ₂ independently represents a linear or branched alkyl or alkoxy group having 1 to 7 carbon atoms, or a carbon number of 2 -7 linear or branched alkenyl.

In some embodiments of the present invention, the compound of the general formula I accounts for more than 1% of the total weight of the cholesteric liquid crystal material; preferably, the compound of the general formula I accounts for the total weight of the cholesteric liquid crystal material More than 20% by weight; more preferably, the compound of Formula I accounts for more than 50% of the total weight of the cholesteric liquid crystal material.

In some embodiments of the invention, the compound of formula I is selected from the group consisting of:

In some embodiments of the present invention, further, the cholesteric liquid crystal material may further comprise one or more compounds selected from Formula II in an amount of 0-60% by weight: II, wherein R _i and R _ii each independently represent H, an alkyl or alkoxy group having 1 to 12 carbon atoms, an alkenyl group or alkenyl group having 2 to 12 carbon atoms; a ring And ring The same or different, each independently , , or Z _i represents a single bond, -CH ₂ CH _2- , -CH ₂ O-, -OCH _2- , -CO-O-, or -O-CO-; a represents 1, 2 or 3, and when a is 2 Or 3 o'clock Can be the same or different.

In some technical solutions of the present invention, further preferably, the compound of the general formula II is selected from the group consisting of the following compounds: Ⅱ-1; Ⅱ-2; Ⅱ-3; Ⅱ-4; Ⅱ-5; Ⅱ-6; Ⅱ-7; Ⅱ-8; Ⅱ-9; Ⅱ-10; Ⅱ-11; Ⅱ-12; Ⅱ-13; Ⅱ-14; II-15; and II-16.

In some technical solutions of the present invention, it is further preferred that R _i and R _ii each independently represent an alkyl or alkoxy group having 1 to 7 carbon atoms, and an alkenyl or alkoxy group having 2 to 7 carbon atoms. base.

In some embodiments of the present invention, it is further preferred that the compound of the general formula II accounts for 0-40% of the total weight of the cholesteric liquid crystal material; still more preferably, the compound of the general formula II accounts for The total weight of the cholesteric liquid crystal material is 0-20%.

In some technical solutions of the present invention, the cholesteric liquid crystal material may further include one or more compounds selected from the general formula III in a total weight of 0-20%: Ⅲ; wherein R ₃ and R ₄ each independently represent a straight or branched chain alkyl or alkoxy group containing 1 to 12 carbon atoms, and a straight or branched chain alkenyl group or alkene containing 2 to 12 carbon atoms Oxygen, -O (CH ₂ ) _p O (CH ₂ ) _q CH ₃ , , or Wherein one or more of -H of the linear or branched alkyl or alkoxy group and the linear or branched alkenyl or alkenyloxy group may be substituted by -F.

In order to prevent the occurrence of electrical breakdown of the device, at least a part of the outermost layer of the microcapsule liquid crystal display device may be provided with an insulating layer. Of course, in order to prevent the occurrence of a device short circuit, an insulation may also be provided between the two flexible conductive layers. Layer, and the insulating layer may be made of an insulating material such as OCA optical glue.

The transparent flexible conductive layer without the light absorption layer may be a transparent substrate covered with a conductive coating (such as a coating formed by conductive ITO, carbon nanotubes, silver nanowires, etc.) on the side near the mixed layer of the microcapsule layer. (Such as PET film).

In some embodiments of the present invention, the light absorbing layer can absorb light in the visible light range, preferably black with a fixed opaque light absorbing background, and the dark black background provides a reflective color image of the liquid crystal display. High contrast, but other opaque colors for fixed backgrounds of cholesteric liquid crystal displays can also be used. The light-absorbing layer can be set separately from the adjacent flexible conductive layer. For example, a dye can be mixed with a heat-curable or UV-curable adhesive to realize the setting of the light-absorbing layer in the form of a coating, and then the light-absorbing layer can be provided separately. The conductive layer (such as conductive silver, etc.) can also be combined with the light-absorbing layer and the adjacent flexible conductive layer. For example, the black conductive glue can be used to achieve the purpose of absorbing light by the light-absorbing layer. Features.

In order to achieve a better thermal printing effect, the thickness of the microcapsule liquid crystal display device is between 10-200 μm except for a transparent flexible conductive layer without a light-absorbing layer.

In some embodiments of the present invention, the particle size of the microcapsules is 0.11 to 50 μm; preferably, the particle size of the microcapsules is 1 to 40 μm; more preferably, the particle size of the microcapsules is 2 ~ 20 μm.

In some embodiments of the present invention, a shell material of the liquid crystal microcapsule is a thermoplastic resin, and a glass transition temperature Tg thereof is preferably 50 to 200 ° C, and more preferably 50 to 120 ° C, which may be specifically selected from polyurea and polymethylmethacrylate. One or more of acrylic resins (such as polymethyl methacrylate, PMMA) and polyethylene terephthalate.

In some embodiments of the present invention, the reflection wavelength of the liquid crystal microcapsules is between 400-650 nm, and the liquid crystal microcapsules can be composed of liquid crystal microcapsules with a single reflection wavelength. The cholesteric liquid crystal is prepared into liquid crystal microcapsules with different reflection wavelengths, and the liquid crystal microcapsules with different reflection wavelengths are mixed to form mixed liquid crystal microcapsules.

In some embodiments of the present invention, the refractive index of the cholesteric liquid crystal is between 0.1-0.25, and the reflection effect is better; the clearing point of the cholesteric liquid crystal is between 50-90 ° C, and the thermal phase transition The effect is better.

In some embodiments of the present invention, the liquid crystal microcapsules can be produced by thermally induced phase separation, polymeric phase separation, lyotropic phase separation or emulsion dispersion.

In some embodiments of the invention, the adhesive comprises a gel material and / or a polymerizable material.

In some embodiments of the present invention, the gel material in the adhesive is selected from the group consisting of polyvinyl alcohol (PVA), polyurethane (PU), polyacrylic acid (PAA), polyvinylpyrrolidone (PVP), protein gel, and One or more of the group consisting of polyvinyl acetate (PVAc).

In some embodiments of the present invention, the polymerizable material in the adhesive is formed from a single polymerizable material by light or heat polymerization.

In some embodiments of the present invention, the polymerizable material in the adhesive may also be formed by polymerizing the polymerizable material and the initiator by light or heat.

In some embodiments of the present invention, the polymerizable material in the adhesive may also be formed by polymerizing the polymerizable material, the initiator, and the auxiliary agent by light or heat.

In some embodiments of the invention, the polymerizable material is composed of an acrylate system or a modified acrylate system.

In some embodiments of the invention, the polymerizable material consists of a vinyl system.

In some embodiments of the invention, the polymerizable material is composed of a vinyl ether system.

In some embodiments of the invention, the polymerizable material consists of an epoxy system.

In some embodiments of the present invention, the quality ratio of the liquid crystal microcapsule to the binder in the microcapsule mixed layer is 2: 8-8: 2, and if the content of the binder is too high, the device is manufactured. The reflectivity will decrease, and if the content of the binder is too low, the device will not support the external stress.

In some embodiments of the present invention, in order to achieve color display, the cholesteric liquid crystal material may further be doped with a dye, preferably a dichroic dye.

In the present invention, one or more layers of the liquid crystal display device can be produced by screw printing, squeegee printing, and screen printing.

The microcapsule liquid crystal display device provided by the present invention can use a common thermal printer (such as a GK 888t type label printer) to achieve thermal printing within 120 ° C. The microcapsule liquid crystal display device can display the printing effect in a curled shape, It can be used as a flexible electronic paper for repeated use.

The beneficial effects of the present invention:

The liquid crystal display device of the present invention uses cholesteric liquid crystals with negative dielectric anisotropy to prepare liquid crystal microcapsules, which are then distributed in an adhesive. With the arrangement of a transparent flexible conductive layer and a light absorption layer, the cholesteric phase can be maintained The steady-state characteristics of liquid crystals in a flexible state. Based on the flexibility of the device, the cholesteric liquid crystals are transformed into a focal conic state by heat or pressure. The printed font can be erased at low voltage (10V Left and right), the cholesteric liquid crystal returns to a flat state and is displayed in color. The microcapsule display device has the characteristics of low driving voltage, high reflectance and contrast, and flexible display. It is suitable for the field of electronic paper and can be used repeatedly. Green Environmental protection.

In order to make the above and other objects, features, and advantages of the present invention more comprehensible, the preferred embodiments are exemplified below and described in detail with reference to the accompanying drawings. It should be noted that the following embodiments are examples of the present invention, and are only used to illustrate the present invention, but not to limit the present invention. Other combinations and various modifications within the concept of the present invention may be made without departing from the spirit or scope of the present invention.

In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it is obvious that the present invention can be implemented without these specific details. In other cases, known structures and devices are shown in block diagram form to avoid unnecessary misunderstandings of the present invention.

For ease of expression, in the following examples, the group structure of the liquid crystal compound is represented by the codes listed in Table 1: Table 1 The group structure code of the liquid crystal compound

Take a compound of the following structural formula as an example: If the structural formula is expressed by the codes listed in Table 1, it can be expressed as: nCPUF, where n represents the number of C atoms of the left alkyl group, for example, n is "3", which means that the alkyl group is -C ₃ H ₇ ; C in the code represents cyclohexane, P in the code represents 1,4-phenylene, and U in the code represents 3,5-difluoro-1,4-phenylene.

The abbreviations of the test projects in the following examples are as follows:

Among them, the optical anisotropy was measured using an Abbe refractometer under a sodium light (589 nm) light source at 25 ° C; V ₁₀ test conditions: DMS505 / square wave / 100HZ, 7μm TN cell; Δε = ε‖-ε⊥ , Where ε‖ is a dielectric constant parallel to the molecular axis, and ε⊥ is a dielectric constant perpendicular to the molecular axis. Test conditions: 25 ° C, 1KHz, 7 μm TN cell.

The HPC850100-100 described below is the trade name of a liquid crystal product manufactured by Jiangsu Hecheng Display Technology Co., Ltd. and is available from the market. The OCA optical glue was purchased from Shenzhen Dalton Electronic Materials Co., Ltd. The film coating machine is a JFA-II film coating machine produced by Shanghai Modern Environment Engineering Technology Co., Ltd. The conductive adhesive is a commercially available GRAPHIT33 conductive adhesive.

The techniques of screw printing, squeegee printing, and screen printing described below are coating techniques generally known to those skilled in the art, and will not be described further below.

Comparative Example 1

Add an appropriate optically active substance to HPC850100-100 (Δε = 28) to adjust it to a cholesteric reflection wavelength of about 546 nm. 80 mL of dichloromethane pre-dissolved with 1 g of PMMA prepolymer was mixed with 1 wt% After mixing 400 mL of polymethacrylic acid (PMAA) in water, 20 g of cholesteric liquid crystals were added, and after mixing to form an emulsion, dichloromethane was removed by solvent evaporation to obtain an aqueous solution containing liquid crystal microcapsules with a diameter of about 10 μm It contains about 50 wt% of liquid crystal microcapsules). Then, the prepared liquid crystal microcapsule aqueous solution and a 20 wt% PVA aqueous solution are mixed uniformly in a volume ratio of 1: 1, and then used.

Conductive PET-ITO with a thickness of 125 μm was selected as the first substrate, and it was placed on a film coating machine to be placed flat. The surface of the substrate was coated with OCA optical adhesive with a thickness of 20 μm by screw printing technology at 100 ° C. After drying at high temperature for 3 minutes, it was polymerized and cured for 3 minutes under 8 mW illumination and 365 nm fluorescent lamp. Then, the surface of the OCA optical glue was coated with a layer of the above-prepared PVA-containing liquid crystal microcapsule solution with a thickness of 40 μm by using a squeegee printing technique, and dried at 40 ° C. for 5 hours. Then, a 20 wt% PVA aqueous solution mixed with an appropriate black dye with a thickness of 10 μm was applied on the film by a blade printing technique, and dried at 40 ° C. for 5 hours. Finally, a layer of conductive silver paste having a thickness of 10 μm is coated by a screw printing technique, and dried at 80 ° C. for 0.5 hours to prepare a microcapsule liquid crystal display device with positive dielectric anisotropy.

The structure of the prepared liquid crystal display device is shown in Fig. 1. The device can be switched to a black state by applying a voltage of 50 V, and a green printing on a black background can be achieved under a normal GK 888t type label printer. The DMS 505 measured the reflectance of the device to be 25% and the contrast ratio (that is, the ratio of the reflection intensity in the planar state to the reflection intensity in the focal cone state) to be 3. The device is flexible and can be used repeatedly.

Example 1

The liquid crystal composition HNL-1 was formulated according to the compounds listed in Table 2 and their weight percentages: Table 2 Formula of the liquid crystal composition and its general performance parameters

Add the appropriate optically active substance to the above HNL-1 to adjust it to a cholesteric reflection wavelength of about 540 nm. 80 mL of dichloromethane pre-dissolved with 1 g of PMMA prepolymer (brand CM-211) and mixed with After mixing a 400 mL aqueous solution of 1 wt% polymethacrylic acid (PMAA), 20 g of cholesteric liquid crystals were added, and after mixing to form an emulsion, dichloromethane was removed by solvent evaporation to obtain liquid crystal microcapsules having a diameter of about 10 μm. Aqueous solution (which contains about 50 wt% liquid crystal microcapsules). Then, the prepared aqueous solution of the liquid crystal microcapsules and the 30 wt% aqueous solution of bone glue are mixed uniformly in a volume ratio of 1: 1 and set aside.

Conductive PET-ITO with a thickness of 125 μm was selected as the first substrate, and it was placed flat on a coating machine. The surface of the substrate was coated with a thickness of 40 μm and mixed with bone glue using screw printing technology. The liquid crystal microcapsule solution was dried at room temperature for 8 hours, so that the mixture was uniformly formed into a film. Then, a 20 wt% PVA aqueous solution mixed with an appropriate black dye with a thickness of 10 μm was applied on the film by a blade printing technique, and dried at 40 ° C. for 5 hours. Next, a layer of conductive silver paste with a thickness of 10 μm was coated by a screw printing technique and dried at 80 ° C. for 0.5 hours. Finally, a 20 μm-thick OCA optical adhesive was coated on the surface of the substrate using lead screw printing technology, dried at a high temperature of 100 ° C for 3 minutes, and then polymerized and cured under an 8 mW illumination and 365 nm fluorescent lamp for 3 minutes. A microcapsule liquid crystal display device with negative dielectric anisotropy can be prepared.

The structure of the prepared liquid crystal display device is shown in Fig. 2. The device can be switched to a planar state by applying a voltage of 10 V. The printing effect of black text on a green background can be achieved under a normal GK 888t label printer (as shown in Figure 5). Using DMS 505, the reflectance of the device was measured to be 32%, and the contrast ratio (that is, the ratio of the reflection intensity in the planar state to the reflection intensity in the focal cone state) was 4. The device was flexible and could be used repeatedly.

Example 2

The liquid crystal composition HNL-2 is formulated according to each compound listed in Table 3 and its weight percentage: Table 3 Formula of the liquid crystal composition and its general performance parameters

An appropriate optically active substance was added to the above HNL-2 to adjust it to a cholesteric reflection wavelength of about 590 nm. 80 mL of dichloromethane pre-dissolved with 1 g of PMMA prepolymer (brand CM-207) was mixed with After mixing a 400 mL aqueous solution of 1 wt% polymethacrylic acid (PMAA), 20 g of cholesteric liquid crystals were added, and after mixing to form an emulsion, dichloromethane was removed by solvent evaporation to obtain a liquid crystal microcapsule containing about 10 μm in diameter. Aqueous solution (containing about 50 wt% liquid crystal microcapsules). Then, the prepared liquid crystal microcapsule aqueous solution and a 30 wt% aqueous solution of bone glue are mixed uniformly in a volume ratio of 4: 6, and then used.

Conductive PET-ITO with a thickness of 125 μm was selected as the first substrate, and it was placed flat on a coating machine. The surface of the substrate was coated with a thickness of 40 μm and mixed with bone glue using screw printing technology. The liquid crystal microcapsule solution was dried at room temperature for 8 hours, so that the mixture was uniformly formed into a film. Then, a 20 wt% PVA aqueous solution mixed with an appropriate black dye with a thickness of 10 μm was applied on the film by a blade printing technique, and dried at 40 ° C. for 5 hours. Next, a layer of black conductive adhesive with a thickness of 20 μm was applied by a screw printing technique, and dried at 80 ° C. for 0.5 hours. Finally, a 20 μm-thick OCA optical adhesive was coated on the surface of the substrate using lead screw printing technology, dried at a high temperature of 100 ° C for 3 minutes, and then polymerized and cured under an 8 mW illumination and 365 nm fluorescent lamp for 3 minutes. A microcapsule liquid crystal display device with negative dielectric anisotropy can be prepared.

The structure of the prepared liquid crystal display device is shown in Fig. 3. The device can be switched to a planar state by applying a voltage of 8 V, and a black print on an orange background can be achieved under a normal GK 888t type label printer. The reflectance of the device measured by DMS 505 is 30%, and the contrast ratio (that is, the ratio of the reflection intensity in the planar state to the reflection intensity in the focal cone state) is 3.8. The device is flexible and can be used repeatedly.

Example 3

An appropriate optically active substance was added to the HNL-2 prepared in Example 2 to adjust it to a cholesteric reflection wavelength of about 620 nm. 80 mL of 2 g of PMMA prepolymer (grade CM-207) was dissolved in advance. Chloromethane was mixed with a 400 mL aqueous solution doped with 1 wt% polymethacrylic acid (PMAA), and 20 g of cholesteric liquid crystal was added. After the mixture was uniformly formed into an emulsion, dichloromethane was removed by solvent evaporation to obtain a diameter of 10 μm. An aqueous solution of left and right liquid crystal microcapsules (which contains about 50 wt% liquid crystal microcapsules). Then, the prepared aqueous solution of the liquid crystal microcapsules and the 30 wt% aqueous solution of bone glue are mixed uniformly in a volume ratio of 1: 1 and set aside.

Select 75 μm-thick conductive PET-ITO as the first substrate, place it flat on a coating machine, and apply screw printing technology to coat the surface of the substrate with a thickness of 40 μm of the above-mentioned mixed bone cement. The liquid crystal microcapsule solution was dried at 40 ° C for 5 hours. Then, a layer of black conductive adhesive with a thickness of 20 μm was applied by a screw printing technique, and dried at 50 ° C. for 0.5 hours. Finally, a 20 μm-thick OCA optical adhesive was coated on the surface of the substrate using lead screw printing technology, dried at a high temperature of 100 ° C for 3 minutes, and then polymerized and cured under an 8 mW illumination and 365 nm fluorescent lamp for 3 minutes. A microcapsule liquid crystal display device with negative dielectric anisotropy can be prepared.

The structure of the produced liquid crystal display device is shown in Fig. 4, and the device can be switched to a planar state by applying a voltage of 8 V. The printing effect of black text on a red background can be achieved under a normal GK 888t label printer (as shown in Figure 6). Using DMS 505, the reflectivity of the device was measured to be 28%, and the contrast ratio (that is, the ratio of the reflection intensity in the planar state to the reflection intensity in the focal cone state) was 3.4. The device is flexible and can be used repeatedly.

Example 4

The liquid crystal composition HNL-3 was formulated according to each compound listed in Table 4 and their weight percentages: Table 5 Liquid crystal composition formula and its general performance parameters

Add the appropriate optically active substance to the above HNL-3 to adjust it to a cholesteric reflection wavelength of about 490 nm. 80 mL of dichloromethane pre-dissolved with 1 g of PMMA prepolymer (brand CM-207) and mixed with After mixing a 400 mL aqueous solution of 1 wt% polymethacrylic acid (PMAA), 20 g of cholesteric liquid crystals were added, and after mixing to form an emulsion, dichloromethane was removed by solvent evaporation to obtain liquid crystal microcapsules having a diameter of about 10 μm. Aqueous solution (which contains about 40 wt% liquid crystal microcapsules). Then, the prepared liquid crystal microcapsule aqueous solution and a 25 wt% bone glue aqueous solution are mixed uniformly in a volume ratio of 1: 1, and then used.

Select 75 μm-thick conductive PET-ITO as the first substrate, place it flat on a coating machine, and apply screw printing technology to coat the surface of the substrate with a thickness of 40 μm of the above-mentioned mixed bone cement. The liquid crystal microcapsule solution was dried at 40 ° C for 5 hours. Then, a layer of black conductive adhesive with a thickness of 20 μm was applied by a screw printing technique, and dried at 50 ° C. for 0.5 hours. Finally, a 20 μm-thick OCA optical adhesive was coated on the surface of the substrate using lead screw printing technology, dried at a high temperature of 100 ° C for 3 minutes, and then polymerized and cured under an 8 mW illumination and 365 nm fluorescent lamp for 3 minutes. A microcapsule liquid crystal display device with negative dielectric anisotropy can be prepared.

The structure of the prepared liquid crystal display device is shown in Fig. 4. The device can be switched to a flat state by applying a voltage of 14 V, and the ordinary GK 888t type label printer can achieve the printing effect of black characters on a blue background. Using DMS 505, the reflectance of the device was 29%, and the contrast ratio (that is, the ratio of the reflection intensity in the planar state to the reflection intensity in the focal cone state) was 3.5. The device was flexible and could be used repeatedly.

Example 5

The liquid crystal composition HNL-4 is formulated according to each compound listed in Table 5 and its weight percentage: Table 6 Formula of the liquid crystal composition and its general performance parameters

An appropriate optically active substance was added to the above HNL-4 to adjust it to a cholesteric reflection wavelength of about 540 nm. 80 mL of dichloromethane pre-dissolved with 1 g of PMMA prepolymer (grade CM-211) was mixed with After mixing a 400 mL aqueous solution of 1 wt% polymethacrylic acid (PMAA), 20 g of cholesteric liquid crystals were added, and after mixing to form an emulsion, dichloromethane was removed by solvent evaporation to obtain a liquid crystal microcapsule containing about 10 μm in diameter. Aqueous solution (containing about 60 wt% liquid crystal microcapsules). Then, the prepared liquid crystal microcapsule aqueous solution and a 25 wt% bone glue aqueous solution are mixed uniformly in a volume ratio of 4: 6, and then used.

Select 75 μm-thick conductive PET-ITO as the first substrate, place it flat on a coating machine, and apply screw printing technology to coat the surface of the substrate with a thickness of 40 μm of the above-mentioned mixed bone cement. The liquid crystal microcapsule solution was dried at 40 ° C for 5 hours. Then, a layer of black conductive adhesive with a thickness of 20 μm was applied by a screw printing technique, and dried at 50 ° C. for 0.5 hours. Finally, a 20 μm-thick OCA optical adhesive was coated on the surface of the substrate using lead screw printing technology, dried at a high temperature of 100 ° C for 3 minutes, and then polymerized and cured under an 8 mW illumination and 365 nm fluorescent lamp for 3 minutes. A microcapsule liquid crystal display device with negative dielectric anisotropy can be prepared.

The structure of the prepared liquid crystal display device is shown in Fig. 4. The device can be switched to a planar state by applying a voltage of 14 V, and a black print on a green background can be achieved under a normal GK 888t type label printer. Using DMS 505, the reflectance of the device was 29%, and the contrast ratio (that is, the ratio of the reflection intensity in the planar state to the reflection intensity in the focal cone state) was 3.5. The device was flexible and could be used repeatedly.

Example 6

Appropriate optically active substances were added to the HNL-2 prepared in Example 2 to adjust the cholesteric reflection wavelengths to be about 480 nm, 550 nm, and 625 nm. Three batches of 1 g PMMA prepolymer were pre-dissolved ( GF1000) 80 mL of dichloromethane was mixed with 400 mL of an aqueous solution containing 1 wt% polymethacrylic acid (PMAA), and 20 g of the above-mentioned cholesteric liquid crystals having different reflection wavelengths were added, and the mixture was uniformly formed into an emulsion. Solvent evaporation was used to remove dichloromethane to obtain an aqueous solution containing liquid crystal microcapsules with different reflection wavelengths of about 10 μm in diameter (which contained about 50 wt% of liquid crystal microcapsules). The aqueous solution was mixed uniformly at a quality ratio of 1: 1: 1, and then the prepared liquid crystal microcapsule aqueous solution and a 30 wt% bone glue aqueous solution were mixed uniformly at a volume ratio of 1: 1 and set aside.

Select 75 μm-thick conductive PET-ITO as the first substrate, place it flat on a coating machine, and apply screw printing technology to coat the surface of the substrate with a thickness of 40 μm of the above-mentioned mixed bone cement. The liquid crystal microcapsule solution was dried at 40 ° C for 5 hours. Then, a layer of black conductive adhesive with a thickness of 20 μm was applied by a screw printing technique, and dried at 50 ° C. for 0.5 hours. Finally, a 20 μm-thick OCA optical adhesive was coated on the surface of the substrate using lead screw printing technology, dried at a high temperature of 100 ° C for 3 minutes, and then polymerized and cured under an 8 mW illumination and 365 nm fluorescent lamp for 3 minutes. A microcapsule liquid crystal display device with negative dielectric anisotropy can be prepared.

The structure of the prepared liquid crystal display device is shown in Figure 4. The device can be switched to a flat state by applying a voltage of 12 V, and a black print on a white background can be achieved under a normal GK 888t type label printer. Using DMS 505, the reflectivity of the device is 29%, and the contrast ratio (that is, the ratio of the reflection intensity in the planar state to the reflection intensity in the focal cone state) is 3.4. The device is flexible and can be used repeatedly.

It can be known from comparison of Comparative Example 1 and Examples 1-6 that the liquid crystal display device provided by the present invention is prepared into liquid crystal microcapsules by using cholesteric liquid crystals having negative dielectric anisotropy, which are then distributed in an adhesive and matched with The arrangement of the transparent flexible conductive layer and the light absorbing layer can maintain the steady state characteristics of the cholesteric liquid crystal in a flexible state, so that the cholesteric liquid crystal can be converted into a focal cone by using heat or pressure based on the flexibility of the device State, the printed font can be erased at low voltage (about 10V), the cholesteric liquid crystal returns to a flat state, and is displayed in color. The microcapsule liquid crystal display device is relatively microcapsules with positive dielectric anisotropy. The liquid crystal display device has the advantages of lower driving voltage, high reflectance and contrast, and flexible display, and is suitable for the field of electronic paper. It can be used repeatedly and is environmentally friendly.

The present invention can also be implemented by various other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications are all It should belong to the protection scope of the claims attached to the present invention.

1‧‧‧ transparent flexible conductive layer

2‧‧‧ Insulation

3‧‧‧ microcapsule mixed layer

3-1‧‧‧Adhesive

3-2‧‧‧LCD microcapsules

4‧‧‧ light-absorbing layer

5‧‧‧ flexible conductive layer

6‧‧‧ conductive light absorbing layer

a‧‧‧ stands for green background effect

b‧‧‧ stands for black effect

c‧‧‧ represents the effect of red background

d‧‧‧ represents the black effect

FIG. 1 is a schematic structural diagram of a microcapsule liquid crystal display device in Comparative Example 1. FIG. FIG. 2 is a schematic structural diagram of a microcapsule liquid crystal display device in Example 1. FIG. FIG. 3 is a schematic structural diagram of a microcapsule liquid crystal display device in Example 2. FIG. FIG. 4 is a schematic structural diagram of a microcapsule liquid crystal display device in Example 3, Example 4, Example 5, and Example 6. FIG. 5 is a printing effect diagram of the first embodiment through a GK 888t label printer. FIG. 6 is a printing effect diagram of the third embodiment through a GK 888t label printer.

Claims (17)

A microcapsule liquid crystal display device includes at least two flexible conductive layers and a microcapsule mixed layer sandwiched between the at least two flexible conductive layers, the at least two flexible conductive layers At least one of the layers is a transparent flexible conductive layer. When the at least two flexible conductive layers are both transparent flexible conductive layers, any one of the flexible conductive layers is provided with a light absorbing layer on the side near the mixed layer of the microcapsules. When a flexible conductive layer is a transparent flexible conductive layer, the non-transparent flexible conductive layer is provided with a light absorbing layer on the side close to the microcapsule mixing layer, and the microcapsule mixing layer is composed of liquid crystal microcapsules and bonding the liquid crystal. The adhesive composition of microcapsules is characterized in that the liquid crystal microcapsules are wrapped with a cholesteric liquid crystal material containing one or more compounds selected from the general formula I: I, wherein R ₁ and R ₂ each independently represent -H, -F, a straight or branched alkyl or alkoxy group containing 1 to 12 carbon atoms, a straight or Branched alkenyl or alkenyloxy, -O (CH ₂ ) _p O (CH ₂ ) _q CH ₃ , , or Wherein one or more of the linear or branched alkyl or alkoxy group and the linear or branched alkenyl or alkenyloxy group -H may be substituted with -F; Z ₁ and Z ₂ each Independently represents a single bond, -CO-O-, -O-CO-, -CH ₂ O-, -OCH _2- , -CH ₂ CH _2- , -CH = CH- or -C≡C-; L ₁ And L ₂ each independently represent -F, -Cl, -CN, or -NCS; And ring Independent representation or ,among them, One or more of -CH ₂ -may be replaced by -O-, One or more of -H may be substituted by halogen; n1 represents 1, 2 or 3, and when n1 is 2 or 3, the ring It can be the same or different, and Z ₁ can be the same or different; n2 represents 0 or 1; p represents an integer from 1 to 12; q represents an integer from 0 to 12. The microcapsule liquid crystal display device according to item 1 of the patent application scope, wherein the compound of the general formula I accounts for more than 1% of the total weight of the cholesteric liquid crystal material. The microcapsule liquid crystal display device according to item 2 of the scope of patent application, wherein the compound of the general formula I is selected from the group consisting of the following compounds: The microcapsule liquid crystal display device according to item 1 of the patent application scope, wherein at least a part of an outermost layer of the microcapsule liquid crystal display device may be provided with an insulating layer. The microcapsule liquid crystal display device according to item 1 of the scope of patent application, wherein the light absorbing layer can absorb light in the visible light range, which can be provided separately from the adjacent flexible conductive layer, or the light absorbing layer and the adjacent The flexible conductive layers are combined into one layer. The microcapsule liquid crystal display device according to item 1 of the scope of patent application, wherein the particle size of the liquid crystal microcapsules is 0.11 to 50 μm. The microcapsule liquid crystal display device according to item 1 of the patent application scope, wherein a shell material of the liquid crystal microcapsule is a thermoplastic resin. The microcapsule liquid crystal display device according to item 1 of the scope of patent application, wherein the reflection wavelength of the liquid crystal microcapsule is between 400-650 nm, and the liquid crystal microcapsule may be a liquid crystal microcapsule having a single reflection wavelength The structure may be a mixture of liquid crystal microcapsules having different reflection wavelengths. The microcapsule liquid crystal display device according to item 1 of the scope of the patent application, wherein the liquid crystal microcapsules can be produced by thermally induced phase separation, polymeric phase separation, lyotropic phase separation, or emulsion dispersion. The microcapsule liquid crystal display device according to item 1 of the patent application scope, wherein the adhesive comprises a gel material and / or a polymerizable material. The microcapsule liquid crystal display device according to item 10 of the patent application scope, wherein the gel material is selected from the group consisting of polyvinyl alcohol, polyurethane, polyacrylic acid, polyvinylpyrrolidone, protein gel, and polyvinyl acetate One or more of them. The microcapsule liquid crystal display device according to item 10 of the scope of patent application, wherein the polymerizable material is made of a single polymerizable material by light or thermal polymerization, or the polymerizable material and an initiator are made by light or thermal polymerization. Or by polymerizing materials, initiators and auxiliaries by photo or thermal polymerization. The microcapsule liquid crystal display device according to item 12 of the application scope, wherein the polymerizable material is composed of an acrylate system or a modified acrylate system, or the polymerizable material is composed of a vinyl system, or The polymerizable material is composed of a vinyl ether system, or the polymerizable material is composed of an epoxy system. The microcapsule liquid crystal display device according to item 1 of the scope of patent application, wherein a quality ratio of the liquid crystal microcapsule to the binder in the microcapsule mixed layer is 2: 8-8: 2. The microcapsule liquid crystal display device according to item 1 of the scope of patent application, wherein the liquid crystal microcapsules may further be doped with a dye. According to the microcapsule liquid crystal display device described in the first item of the patent application scope, one or more layers of the liquid crystal display device can be produced by screw printing, squeegee printing, and screen printing. Application of the liquid crystal display device according to any one of claims 1 to 16 in the scope of application for manufacturing electronic paper.