TW202344632A - An alignment coating solution and application thereof - Google Patents

Abstract

The invention discloses an alignment coating solution and application thereof, comprising the following raw material components by mass percentage: liquid crystal guide agent: 8-15%; solvent: 60-85%; surfactant: 3-8%. The alignment coating solution is mainly composed of a liquid crystal guide agent, and can align the liquid crystal layer formed by the liquid crystal coating solution. The alignment coating solution can be used to prepare liquid crystal films. During preparation, an oriented alignment layer is prepared by the alignment coating solution, and then a liquid crystal coating solution is applied to obtain a liquid crystal layer with a multi-layered liquid crystal lattice structure. And then the Bragg reflection occurs, thus a liquid crystal film with a multicolored effect is obtained.

Description

Alignment coating liquid and its application

The invention belongs to the technical field of polymer materials. Specifically, it is an alignment coating liquid and its application.

With the popularity of electronic products in public life, people have begun to pursue the appearance design of products. Whether it is mobile phones, tablets, laptops and other electronic products, the appearance characteristics of the product need to satisfy the aesthetics of most consumers to the greatest extent. concept. At present, in order to attract consumers' attention, electronic products have also appeared in many differentiated designs in appearance. Taking the back cover of mobile phones as an example, there are various effects such as matte, shiny and colorful effects, which can improve the appearance of mobile phones. Among them, glossy and colorful effects are favored by consumers because of their strong visual impact.

We know that the back cover of mobile phones is mainly made of metal, glass and engineering plastics. Although metal materials have a shiny effect, when used as a mobile phone back cover, they have disadvantages such as difficulty in coloring and electromagnetic shielding properties. Although glass material has no magnetic field interference, it is fragile under the action of external force and has poor fall resistance and wear resistance. Engineering plastics, such as the existing composite board back cover, not only have the advantages of metal and glass materials, but can also achieve a colorful appearance through coating. Therefore, they are deeply loved by young consumers.

In the prior art, the utility model with the announcement number CN214381674U discloses a shell composed of a matrix, a liquid crystal optical film layer and a reflective layer. The matrix is made of polycarbonate (PC) and polymethylmethacrylate (polymethylmethacrylate). PMMA) composite sheet; its liquid crystal optical film layer contains oriented liquid crystal. On the one hand, the incident light entering the liquid crystal optical film layer can be reflected by the reflective layer, thereby improving the overall brightness and gloss of the shell; on the other hand, the process The oriented liquid crystal displays a certain main color after reflecting the light, and the wavelength of the reflected light changes with the incident angle of the incident light, so that when the user observes from different angles, the liquid crystal optical film layer observed will appear different. The color will be red-shifted or blue-shifted as the viewing angle changes, ultimately giving the entire housing a colorful effect; its reflective layer can improve the brightness and gloss of the housing, and can cooperate with the liquid crystal optical film layer to make the housing Presents a bright and colorful effect. It can be seen that this patent discloses the combination of a liquid crystal optical film layer and a reflective layer, and uses the combination of the reflective layer and the liquid crystal layer to achieve a colorful effect. However, since the optical film in this patent is composed of a liquid crystal optical film layer and a multi-layer reflective layer, it greatly increases the thickness of the back cover of the mobile phone, which is not conducive to the lightweight of the back cover of the mobile phone, thus making the consumer experience worse. In addition, due to the existence of multi-layer reflective layers, the production cost of the back cover of the mobile phone will also be increased and the preparation cycle will be greatly extended.

The object of the present invention is to provide an alignment coating liquid. The alignment coating liquid is composed of a liquid crystal guide agent as a main component and can induce alignment for the liquid crystal layer formed by the liquid crystal coating liquid. To this end, the present invention also provides the alignment coating liquid in For applications in preparing liquid crystal films, an aligned alignment layer is prepared by coating an alignment coating liquid on a support, and then the liquid crystal coating liquid is coated on the alignment layer to obtain a liquid crystal layer with a more regularly arranged multi-layer liquid crystal lattice structure. , Bragg reflection occurs, and a liquid crystal film with a phantom effect is obtained.

The present invention is realized through the following technical solution: an alignment coating liquid includes the following raw material components in mass percentage: Liquid crystal guide agent: 8~15%; Solvent: 60~85%; Surfactant: 3~8%.

The liquid crystal guide agent is water-soluble polyvinyl alcohol and/or its derivatives. Its derivatives include: polyvinyl formal, polyvinyl acetal, polyvinyl butyral, polyvinyl phthalate, etc.

The solvent is mainly water, and may also contain other solvents, including but not limited to at least one of alcohols, esters, ketones, benzene, and ketoamide solvents. For example: alcohols such as methanol and ethanol; toluene, xylene, cumene, trimethylbenzene; ester solvents such as methyl acetate, ethyl acetate, propyl acetate, butyl acetate; acetone, methyl ethyl ketone, Ketone solvents such as methyl isobutyl ketone, cyclohexanone, and cyclopentanone; ether solvents such as tetrahydrofuran, 1,2-dimethoxyethane, and anisole; N,N-dimethylformamide , N-methyl-2-pyrrolidinone and other amide solvents; propylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether acetate, γ-butyrolactone, chlorobenzene, etc. They may be used alone or in a mixture of two or more types. In the present invention, one type of alcohol solvent may be preferably used or two or more types may be mixed and used.

Surfactants can improve the coating properties of the alignment layer solution and the liquid crystal coating solution. In the present invention, the surfactants include but are not limited to nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants. , silicone surfactants, polyalkylene oxide surfactants or fluorosurfactants.

The present invention also includes: applying the above-mentioned alignment coating liquid in preparing a liquid crystal film, coating the alignment coating liquid on a support, drying on the support to obtain an alignment film, and then performing rubbing alignment to obtain an alignment layer. A liquid crystal coating liquid is coated on the alignment layer to prepare a liquid crystal film.

The support body is a film made of thermoplastic resin through extrusion molding. One or a mixture of polyester resin, polycarbonate resin, polystyrene resin, polyacrylate resin, polymethacrylate resin, polyurethane resin, polyethylene resin and polyvinyl chloride resin can be used, such as poly Ethylene terephthalate resin (PET).

The coating method of the alignment coating liquid can adopt the existing known rod coating method, applicator method, spin coating method, roll coating method, direct gravure coating method, reverse gravure coating method, flexographic coating method, inkjet method, and die coating method. , capcoating, dip coating, slot coating, etc. In actual operation, the support body is continuously transported in the transportation direction, and then the alignment coating liquid is applied to the support body using any of the above coating methods.

The drying equipment can adopt existing known methods such as hot air heating, near infrared heating, far infrared heating and microwave heating.

In the present invention, the drying temperature is 80-100°C, and the drying time is 3-10 minutes; the friction alignment is to use paper, gauze, felt, rubber, nylon or polyester fiber on the surface of the alignment film along the same By rubbing in the direction, the oriented alignment layer can be obtained.

The support body provided with the alignment layer meets the following indicators: Thickness tolerance: ±1um; Light transmittance: ≥90%; Haze: ≤2%; Dyne value: ≥34dyne.

The liquid crystal coating liquid is cholesterol liquid crystal. Under the action of the alignment layer, the molecules of each layer of the cholesterol liquid crystal are arranged in a multi-layered structure and form a Bragg reflection structure. Therefore, when the angle of the observer changes, the color can change significantly and continuously. The changes produce a phantom effect. In terms of mass percentage, the cholesterol liquid crystal includes 12-38% of achiral polymerizable monomers, 2-5% of chiral polymerizable monomers, 0.03-3% of initiators, 1-3% of auxiliaries and 60-60% of solvents. 80%.

Further, achiral polymerizable monomers include bifunctional polymerizable monomers and monofunctional polymerizable monomers:

The bifunctional polymerizable monomer satisfies the following formula: (a)

In the above formula, m and n respectively represent any natural number from 4 to 8, and R ₁ represents a hydrogen atom, methyl, ethyl, methoxy, ethoxy, phenyl, benzyl or ester group, etc.

For example: m and n are 4 respectively, R ₁ is a polymerized monomer of hydrogen atom; m and n are 6 respectively, R ₁ is a polymerized monomer of methoxy group, etc.

The monofunctional polymerizable monomer satisfies the following formula: (b)

In the above formula, R ₂ represents a hydrogen atom, methyl group, ethyl group, methoxy group, ethoxy group, phenyl group, benzyl group or ester group, etc.

For example, R ₂ is a polymerized monomer of hydrogen atom; R ₂ is a polymerized monomer of methyl group; R ₂ is a polymerized monomer of phenyl group, etc.

Chiral polymerizable monomers can be selected from CN, CB15, S811, R1011, and chiral agents with the structure shown in the following formula: (c)

Initiators include, but are not limited to, azo, peroxy and redox types. It can also be divided into water-soluble initiators (such as inorganic persulfates, hydrogen peroxide, water-soluble azo initiators, etc.) and oil-soluble (soluble in monomers or organic solvents) organic initiators according to their solubility properties. The polymerizable liquid crystal composition (cholesterol liquid crystal) of the present invention preferably contains at least one polymerization initiator such as a thermal polymerization initiator or a photopolymerization initiator. As a thermal polymerization initiator, benzoyl peroxide, 2,2'-azobisisobutyronitrile, etc. can be used. In addition, as photopolymerization initiators, benzoin ethers, benzophenones, acetophenones, benzoyl ketals, and sulfide initiators can be used. Ketones etc.

Auxiliaries can be flame retardants, defoaming agents, and hardening accelerators. Among them, flame retardants are mainly halogen-free flame retardants, which can be phosphorus-based flame retardants, nitrogen-based flame retardants, intumescent flame retardants, etc., and further can be tricresyl phosphate, triphenyl phosphate, triisophosphate Propyl phenyl ester, tributyl phosphate, trioctyl phosphate, tolyl diphenyl phosphate, melamine, etc. The preferred defoaming agent is organosilicon defoaming agent. Among H ₂ O and ordinary oils, silicone oil has high activity and low solubility. Its basic characteristics are stable chemical properties, wide range of use, low volatility, It is non-toxic and has outstanding defoaming ability. Specifically, it can be polydimethylsiloxane, ethylene glycol siloxane, hydroxy silicone oil, fluorosiloxane, etc. In order to ensure the mechanical strength of the formed liquid crystal layer and the stability of the liquid crystal orientation, the hardening accelerator can be selected from: phenol group, silanol group, thiol group, phosphate group, sulfonic acid group, carboxyl group, carboxylic acid anhydride group, etc. Compounds, of which compounds having a phenol group or a silanol group are preferred. Specific examples of compounds having a phenol group include cyanophenol, nitrophenol, methoxyphenoxyphenol, thiophenoxyphenol, 4-benzylphenol, and the like; compounds having a silanol group Examples of the compound include trimethylsilanol, triethylsilanol, 1,4-bis(hydroxydimethylsilyl)benzene, triphenylsilanol, diphenylsilanediol, and the like.

The solvent is an organic solvent, selected from one or more of toluene, xylene, cumene, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, acetone, butanone, dipentanone, cyclopentanone, etc. species.

The liquid crystal film meets the following indicators: Thickness: ±8%; Light transmittance: ≥85%; Haze: ≤3%; Core wavelength tolerance: ±5nm; Reflectivity: ≥40%.

Compared with the existing technology, the present invention has the following advantages and beneficial effects:

(1) The present invention provides an alignment coating liquid that can be used to prepare a liquid crystal film with a phantom effect. The alignment coating liquid uses a liquid crystal guide agent as the main component, and is supplemented with a solvent and a surfactant to form an alignment layer. The liquid crystal coating liquid coated on it induces orientation, and the resulting liquid crystal layer has a more regular multi-layer liquid crystal lattice structure. There is no need to add a reflective layer or other alignment layer to achieve a bright phantom effect.

(2) In the present invention, an aligned alignment layer is formed by coating the alignment coating liquid on the support, drying, and rubbing the alignment, and then coating the liquid crystal coating liquid on the alignment layer to form a liquid crystal layer with a phantom effect. Actual preparation At this time, the release method can be used to transfer the liquid crystal layer to the substrate to obtain a colorful shell. The preparation process is simple and the operation is convenient. Both the alignment coating liquid and the liquid crystal coating liquid can be realized by continuous winding coating, which is easy to produce on a large scale. large-scale mass production and improve production efficiency.

(3) The liquid crystal film involved in the present invention has a simple structure and can achieve high transmittance and phantom effects with a single liquid crystal layer. Compared with the existing colorful shell formed by a (multi-layer) reflective layer and a liquid crystal layer, it is much more transparent. The preparation cycle of the shell is shortened and the production cost is reduced.

(4) The present invention is suitable for use as casings for electronic products, especially portable electronic products such as mobile phone back covers, notebook computers, and tablet computers. The structure is light and thin, easily favored by users, and the appearance is bright and colorful, which can satisfy users' needs. The pursuit of appearance effect. During preparation, a layer of liquid crystal (cholesterol liquid crystal film) prepared from an alignment coating solution is directly attached to a substrate with high reflectivity and high transmittance to achieve a bright and colorful effect of the shell.

The present invention will be further described in detail below with reference to examples, but the implementation of the present invention is not limited thereto.

Example 1: Alignment Coating Liquid I Prepare alignment coating liquid I according to the following formula: 15% polyvinyl alcohol, 80% methanol and water, and 5% fluorinated surfactant.

Example 2: Alignment Coating Liquid II Prepare alignment coating liquid II according to the following formula: 8% polyvinyl alcohol, 85% methanol and water, and 7% anionic surfactant.

Example 3: Alignment Coating Liquid III Prepare alignment coating liquid III according to the following formula: 10% polyvinyl alcohol, 82% methanol and water, and 8% fluorinated surfactant.

Example 4: Alignment Coating Liquid IV Prepare alignment coating liquid IV according to the following formula: 11% polyvinyl alcohol, 85% methanol and water, and 4% cationic surfactant.

Example 5: Alignment Coating Liquid V Prepare alignment coating liquid V according to the following formula: 12% polyvinyl alcohol, 80% methanol and water, and 8% fluorinated surfactant.

Example 6: Alignment Coating Liquid VI Prepare alignment coating liquid VI according to the following formula: 15% polyvinyl alcohol, 80% methanol and water, and 5% fluorinated surfactant.

Example 7: Liquid crystal film Ⅰ Prepare liquid crystal coating liquid Ⅰ according to the following formula: 10% of the monomer satisfying formula (a) (where m and n are 4 respectively, R ₁ is a hydrogen atom), 10% of the monomer satisfying formula (b) (R ₂ is methyl) 8%, CN 3%, 2,2'-azobisisobutyronitrile 0.15%, tricresyl phosphate 1%, polydimethylsiloxane 1%, trimethylsilane Alcohol 1% and toluene 76%.

Coat the above-mentioned alignment coating liquid I on PET with a thickness of 100 μm according to the gravure coating method. After coating, send it to the hot air drying equipment and heat it at 80-85°C for 5 minutes to form an alignment film on the PET film. Use gauze to clean the PET film. An alignment layer is formed by friction alignment, and the performance index of PET provided with this alignment layer meets the range shown in Table 1. The above-mentioned liquid crystal coating liquid I is coated on the alignment layer according to the gravure coating method, and then sent to a multi-stage oven after coating. In the first drying box, the drying temperatures are set to 70~75°C, 80~85°C and 95~100°C respectively along the conveying direction; then it passes through the cooling box for cooling to a temperature of 20~22°C; finally, it enters the second drying box. The second drying box is tempered and dried again. The tempering temperature is set to 90~100℃, 80~90℃ and 70~80℃ along the conveying direction. After tempering treatment, it is then irradiated with 350nm ultraviolet light. Curing 15s, curing capacity is 350mj/cm ² . The liquid crystal coating is polymerized and cross-linked to solidify and form a liquid crystal layer, namely liquid crystal film I. Table 1 Performance indicators of PET with alignment layer parameters indicator Test method Thickness tolerance ±1um GB/T 33051 Transmittance ≥90% JIS K7361 test method Haze ≤2% JIS K7361 test method Dyne value ≥34dyne Arcotest dyne pen

Example 8: Liquid crystal film II. Prepare liquid crystal coating liquid II according to the following formula: 15% of the monomer satisfying formula (a) (where m and n are 6 respectively, and R ₁ is methoxy), and 15% of the monomer satisfying formula (b). 20% of monomer ( _R2 is methyl), 2% of chiral agent satisfying formula (c), 0.05% of benzoin ether initiator, 0.05% of tricresyl phosphate, 0.05% of hydroxyl silicone oil, trimethylsilane Alcohol 0.05% and toluene 62.8%.

Coat the above-mentioned alignment coating liquid II on PET with a thickness of 80 μm according to the gravure coating method. After coating, send it to the hot air drying equipment and heat it at 95-100°C for 8 minutes to form an alignment film on the PET film. Use gauze to clean the PET film. An alignment layer is formed by friction alignment, and the performance index of PET provided with this alignment layer meets the range shown in Table 1. The above-mentioned liquid crystal coating liquid II is coated on the alignment layer according to the gravure coating method, and then sent to a multi-stage oven after coating. In the first drying box, the drying temperatures are set to 75-80°C, 80-85°C and 90-95°C respectively along the conveying direction; then it passes through the cooling box for cooling to a temperature of 35-40°C; and finally enters the second drying box. The second drying box is tempered and dried again. The tempering temperature is set to 90~100℃, 80~90℃ and 70~80℃ along the conveying direction. After tempering treatment, it is then irradiated with 350nm ultraviolet light. Curing 20s, curing capacity is 350mj/cm ² . The liquid crystal coating is polymerized and cross-linked to solidify and form a liquid crystal layer, namely liquid crystal film II.

Example 9: Liquid crystal film III. Liquid crystal coating liquid III was prepared according to the following formula: 25% of the monomer satisfying formula (a) (where m is 4, n is 6, and R ₁ is methyl), and the monomer satisfying formula (b) 5% monomer (where R ₂ is phenyl), R1011 5%, 1% benzoyl peroxide, 1% tricresyl phosphate, 0.5% 1,4-bis(hydroxydimethylsilyl)benzene and ethyl acetate Ester 62.5%.

Coat the above-mentioned alignment coating liquid III on PET with a thickness of 120 μm according to the gravure coating method. After coating, send it to the hot air drying equipment and heat it at 95-100°C for 3 minutes to form an alignment film on the PET film. Use gauze to clean the PET film. An alignment layer is formed by friction alignment, and the performance index of PET provided with this alignment layer meets the range shown in Table 1. The above-mentioned liquid crystal coating liquid III is coated on the alignment layer according to the gravure coating method, and then sent to a multi-stage oven after coating. In the first drying box, the drying temperatures are set to 70~75°C, 85~90°C and 95~100°C respectively along the conveying direction; then it passes through the cooling box for cooling to a temperature of 30°C; and finally enters the second drying box. Dry box, temper and dry again. The tempering temperature is set to 90~100℃, 80~90℃ and 70~80℃ along the conveying direction. After tempering treatment, it is then cured under 370nm ultraviolet light for 10 seconds. , the curing capacity is 350mj/cm ² . The liquid crystal coating is polymerized and cross-linked to solidify and form a liquid crystal layer, namely liquid crystal film III.

Example 10: Liquid crystal film IV Prepare liquid crystal coating liquid IV according to the following formula: 6% of the monomer satisfying formula (a) (where m and n are 5 respectively, R ₁ is phenyl), 6% of the monomer satisfying formula (b) (R ₂ is ethyl) 6%, chiral agent satisfying formula (c) 5%, 2,2'-azobisisobutyronitrile 1.5%, polydimethylsiloxane 0.5%, cyanophenol 1% and xylene 80%.

Coat the above-mentioned alignment coating liquid IV on PET with a thickness of 150 μm according to the gravure coating method. After coating, send it to the hot air drying equipment and heat it at 85-90°C for 6 minutes to form an alignment film on the PET film. Use gauze to clean the PET film. An alignment layer is formed by friction alignment, and the performance index of PET provided with this alignment layer meets the range shown in Table 1. The above-mentioned liquid crystal coating liquid IV is coated on the alignment layer according to the gravure coating method, and then sent to a multi-stage oven after coating. In the first drying box, the drying temperatures are set to 70~75°C, 80~85°C and 90~95°C respectively along the conveying direction; then it passes through the cooling box for cooling to a temperature of 35°C; and finally enters the second drying box. Dry box, temper and dry again. The tempering temperature is set to 90~100℃, 80~90℃ and 70~80℃ along the conveying direction. After tempering treatment, it is then cured under 370nm ultraviolet light for 10 seconds. , the curing capacity is 350mj/cm ² . The liquid crystal coating is cured by polymerization and cross-linking, and forms a liquid crystal layer, namely liquid crystal film IV.

Example 11: Liquid crystal film V. Liquid crystal coating liquid V was prepared according to the following formula: 15% of the monomer satisfying formula (a) (where m and n are 4 respectively, and R ₁ is a hydrogen atom), and 15% of the monomer satisfying formula (b). (R ₂ is methyl) 10%, 4% chiral agent satisfying formula (c), 0.05% benzophenone initiator, 1% tricresyl phosphate, 0.5% polydimethylsiloxane, Trimethylsilanol 1.45% and toluene 68%.

Coat the above-mentioned alignment coating liquid V on PET with a thickness of 300 μm according to the gravure coating method. After coating, send it to the hot air drying equipment and heat it at 95 to 100°C for 10 minutes to form an alignment film on the PET film. Use gauze to clean the PET film. An alignment layer is formed by friction alignment, and the performance index of PET provided with this alignment layer meets the range shown in Table 1. The above-mentioned liquid crystal coating liquid V is coated on the alignment layer according to the gravure coating method, and then sent to a multi-stage oven after coating. In the first drying box, the drying temperature is set to 75~80℃, 90℃ and 100℃ respectively along the conveying direction; then it passes through the cooling box for cooling, and the temperature is 38℃; finally it enters the second drying box, and again Tempering and drying, the tempering temperature is set to 90~95℃, 80~85℃ and 70~75℃ along the conveying direction. After tempering treatment, it is then cured under 370nm ultraviolet light for 10 seconds. The curing ability is 350mj/cm ² . The liquid crystal coating is cured by polymerization and cross-linking, and forms a liquid crystal layer, that is, liquid crystal film V.

Example 12: Liquid crystal film VI. Liquid crystal coating liquid VI was prepared according to the following formula: 17% of monomers satisfying formula (a) (where m and n are 4 respectively, and R ₁ is a hydrogen atom), and 17% of monomers satisfying formula (b). (R ₂ is methoxy) 10%, S811 4%, 2,2'-azobisisobutyronitrile 1%, fluorosiloxane 1%, nitrophenol 1% and toluene 66%.

Coat the above-mentioned alignment coating liquid VI on PET with a thickness of 270 μm according to the gravure coating method. After coating, send it to the hot air drying equipment and heat it at 95 to 100°C for 10 minutes to form an alignment film on the PET film. Use gauze to clean the PET film. An alignment layer is formed by friction alignment, and the performance index of PET provided with this alignment layer meets the range shown in Table 1. The above-mentioned liquid crystal coating liquid VI is coated on the alignment layer according to the gravure coating method, and then sent to a multi-stage oven after coating. In the first drying box, the drying temperatures are set to 75~80°C, 90°C and 100°C respectively along the conveying direction; then it passes through the cooling box for cooling to a temperature of 35°C; finally it enters the second drying box and again Tempering and drying, the tempering temperature is set to 90~95℃, 80~85℃ and 70~75℃ along the conveying direction. After tempering treatment, it is then cured under 350nm ultraviolet light for 15s. The curing ability is 350mj/cm ² . The liquid crystal coating is cured by polymerization and cross-linking, and forms a liquid crystal layer, that is, liquid crystal film VI.

The liquid crystal films involved in the above-mentioned Examples 7 to 12 were respectively subjected to experiments, and their performance indicators were measured as shown in Table 2 below. Table 2 Performance indicators of liquid crystal film thickness Transmittance Haze Core wavelength tolerance Reflectivity Liquid crystal film Ⅰ 103um 92% 1.1% ±3nm 45% Liquid crystal film Ⅱ 83um 93% 1.0% ±3nm 46% Liquid crystal film III 124um 93% 1.0% ±3nm 45% Liquid crystal film IV 154um 93% 1.0% ±2nm 45% Liquid crystal film Ⅴ 303um 92% 1.2% ±3nm 45% Liquid crystal film VI 273um 92% 1.2% ±3nm 45% Test method GB/T 33051 JIS K7361 JIS K7361 UH4150 UH4150

Embodiment 13: The back cover of the Symphony mobile phone is glued with the above-mentioned liquid crystal film I through a rubber roller, the speed of the rubber roller is 6m/min, and the glue gap is 100 microns. After the glue is applied, the liquid crystal film and PC/PMMA composite board (performance index As shown in Table 3 below, of course, PC or PMMA can also be used for lamination, and LED lamp curing and mercury lamp curing are performed. The LED lamp power is 50%, the mercury lamp temperature is 80°C, and the mercury lamp current is 35A. Remove the support body. That is, a colorful mobile phone back cover composed of a composite of liquid crystal film and PC/PMMA is obtained. Table 3 Performance indicators of PC/PMMA composite boards parameters indicator Test method Reflectivity ≥50% UH4150 test method Transmittance ≥75% JIS K7361 test method Haze <2% JIS K7361 test method hardness 500g/F JIS K5600 test method Flame retardant properties No puncture within 60 seconds of burning IEC 60695 test method

The above-mentioned Symphony mobile phone back cover was tested, and its performance indicators were measured as shown in Table 4 below. Table 4 Performance indicators of the Symphony back cover parameters indicator Test method Transfer adhesion 5B GB9286-98 Haze 1.5% JIS K7361 Core wavelength tolerance ±3nm UH4150 Reflectivity 41% UH4150

The structure of liquid crystal film I can be seen in Figure 1. It can be seen from Figure 1 that the molecules in each layer of liquid crystal film I are arranged in a multi-layered structure, which can form a Bragg reflection structure. When the angle of the observer changes, the color can change significantly. The continuous changes produce a phantom effect. The phantom effect of the phantom mobile phone back cover prepared by the liquid crystal film I is shown in Figure 2. It can be seen from Figure 2 that under different visual angles, observers can observe different phantom effects presented by the mobile phone back cover. For example, in Figure 2, the back cover of the mobile phone appears red at 0°, yellow at 45°, and green at 70°.

For pictures of liquid crystal film I, please refer to the photo shown in Figure 3. Liquid crystal film I shows different gradient colors with different angles of incident light, and also has a certain light transmittance. For example, the liquid crystal film shown in a has a gradient from green to yellow to red along the direction of the arrow. The liquid crystal film shown in b has a gradient from orange to red along the direction of the arrow. For pictures of the colorful mobile phone back covers made from the liquid crystal film I, please refer to the photos shown in Figure 4. For the same colorful mobile phone back covers (a total of 7 identical mobile phone back covers from left to right), the photos are taken from different angles. We took photos of three groups A, B, and C in order. As can be seen from Figure 3, the colors of the back covers of the 7 same mobile phones taken at the same angle are all different. At the same time, when the shooting angle changes, the color of the back cover of the corresponding mobile phone changes. The covers are all in gradient color.

Comparative ratio: This comparative example is a comparative example with Example 7 and Example 13. The only difference is that no alignment coating liquid is used. During the preparation process, the same process method and parameter standards as in Example 7 and Example 13 are used. The liquid crystal coating liquid is coated on PET to prepare a liquid crystal film with a corresponding liquid crystal layer. Finally, a mobile phone back cover is prepared in the same manner.

Comparing the back cover of this mobile phone with the colorful mobile phone back cover prepared in Example 13, the experimenter can find that the back cover of the mobile phone in the comparative example also shows a certain color change when the angle of the incident light changes. , but the color change is relatively simple, usually one color jumps directly to another color, there is no presentation of multiple colors during the gradient process, and there is no phantom effect on the back cover of the phantom mobile phone in Embodiment 13. Therefore, for the observer, It also has no obvious visual impact.

The above are only preferred embodiments of the present invention and do not impose any formal restrictions on the present invention. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention fall within the scope of the present invention. within the scope of protection.

a, b: arrow A, B, C: Group

Figure 1 is a structural diagram of a liquid crystal film. Figure 2 is a schematic diagram of different visual phantom effects on the back cover of a phantom mobile phone. Figure 3 is a picture of the liquid crystal film. Figure 4 is a comparison picture of the back cover of the Symphony phone.

Claims (10)

An alignment coating liquid includes the following raw material components in mass percentages: Liquid crystal guide agent: 8~15%; Solvent: 60~85%; Surfactant: 3~8%. The alignment coating liquid according to claim 1, wherein the liquid crystal guide agent is water-soluble polyvinyl alcohol and/or its derivatives. The alignment coating liquid according to claim 1, wherein the solvent includes at least one of alcohols, esters, ketones, benzene, and ketoamide solvents. The alignment coating liquid according to claim 1, wherein: the surfactant includes nonionic surfactant, anionic surfactant, cationic surfactant, amphoteric surfactant, silicone surfactant, polyalkylene oxide Surfactants or fluorosurfactants. An application of the alignment coating liquid described in claim 1 in preparing a liquid crystal film, wherein: the alignment coating liquid is coated on a support, and the alignment film is obtained after drying on the support, and then the alignment layer is obtained by rubbing alignment, A liquid crystal coating liquid is coated on the alignment layer to prepare a liquid crystal film. The application as claimed in claim 5, wherein the support body is a film made of thermoplastic resin through extrusion molding. The application as described in claim 5, wherein: the drying temperature is 80-100°C, and the drying time is 3-10 minutes; the friction alignment is using paper, gauze, felt, rubber, nylon or polyester fiber on The surface of the alignment film is rubbed in the same direction to obtain an aligned alignment layer. The application as described in claim 5, wherein: the support body provided with the alignment layer meets the following indicators: Thickness tolerance: ±1um; Light transmittance: ≥90%; Haze: ≤2%; Dyne value: ≥34dyne. The application as described in claim 5, wherein: the liquid crystal coating liquid is cholesterol liquid crystal, and in terms of mass percentage, the cholesterol liquid crystal includes 12 to 38% of achiral polymerizable monomers and 2 to 38% of chiral polymerizable monomers. 5%, initiator 0.03~3%, additive 1~3% and solvent 60~80%. The application as described in claim 5, wherein: the liquid crystal film meets the following indicators: Thickness: ±8%; Light transmittance: ≥85%; Haze: ≤3%; Core wavelength tolerance: ±5nm; Reflectivity: ≥40%.