WO2019015018A1

WO2019015018A1 - Full-solid state reflecting film and preparation method therefor

Info

Publication number: WO2019015018A1
Application number: PCT/CN2017/099009
Authority: WO
Inventors: 罗丹; 李勇
Original assignee: 南方科技大学
Priority date: 2017-07-17
Filing date: 2017-08-25
Publication date: 2019-01-24
Also published as: CN107300726A

Abstract

Disclosed are a full-solid state reflecting film and a preparation method therefor. The reflecting film comprises: a polymer matrix having a micro-cavity, and a filling medium filled in the micro-cavity; and the micro-cavity in the reflecting film is of a spiral structure. The preparation method for the reflecting film comprises: 1) preparing a first composite layer, containing an alignment layer, on a first substrate; 2) preparing a second composite layer, containing an alignment layer, on a second substrate; 3) preparing a liquid crystal cell by using the first composite layer and the second composite layer; 4) injecting a cholesteric liquid crystal, a photoinitiator and a polymer monomer into the liquid crystal cell; 5) polymerization; 6) using a solvent for soaking and dissolution, and then removing and drying the film material; 7) injecting a filler into the film layer obtained after drying, and curing same to obtain the reflecting film. The reflecting film has the advantages of a full solid-state, being flexible and shapeable, and high reflectivity, and can be completely separated from the substrate. The reflecting film can be widely applied to a series of optical device products.

Description

All-solid reflective film and preparation method thereof

Technical field

The present disclosure belongs to the field of photonic crystal reflective films, and relates to an all-solid reflective film and a preparation method thereof, for example, an all-solid reflective film and a preparation method thereof.

Background technique

Liquid crystal is a special form of matter in which the state of matter is between solid crystals and traditional liquids. Today, liquid crystals have been widely used in displays and various types of optical photonic devices. The cholesteric liquid crystal self-assembles in an anti-parallel liquid crystal cell to form a one-dimensional photonic crystal structure, which is sensitive to the external environment, such as temperature, electromagnetic field, light field, stress, and the like. Therefore, cholesteric liquid crystals are widely used in dynamic gratings, electronically controlled optical switches, broadband polarizers, liquid crystal lasers, and bistable reflective liquid crystal displays.

The cholesteric liquid crystal reflects the same circularly polarized light as the hand shape, and the reflection center wavelength is: λ ₀ = n _av * P, where n _av is the average refractive index of the liquid crystal molecules, and p is the pitch. The line width of the reflection band gap: An*p=(n _e -n ₀ )*p (n _e is a very light refractive index, and n ₀ is a constant light refractive index). A plurality of optical devices as described above can be prepared by the above characteristics. Due to the needs of some occasions, polymer cholesteric liquid crystals have been extensively studied, and many polymer-based studies have been conducted to reduce the driving voltage and response time. However, in the prior art, cholesteric liquid crystals have not been used to successfully prepare high reflection. The rate of reflective film is successfully studied.

CN 103869393 A discloses a reflective film for a liquid crystal display, in which a first polyester layer is laminated on at least one side of a second polyester layer containing hollow resin ions incompatible with polyester, and the reflection The film satisfies the following conditions: 1) the first polyester layer has a thickness of 10 to 30 μm; 2) the first polyester layer contains 5 to 20% of inorganic particles based on the total weight of the first polyester layer; and 3) the second polyester The thickness of the layer is 100 μm or more; and 4) the second polyester layer contains hollow resin particles which are incompatible with the polyester in an amount of 10 to 40% by weight based on the total weight of the second polyester layer. It has good mechanical properties and reflectivity, but the inorganic filler particles and medium The use of empty resin particles deteriorates the brittleness of the film and is limited in practical applications.

In the real demand, the non-substrate, all solid state, high reflectivity reflective film is a hot topic in today's application, and its research is of great significance.

Summary of the invention

The following is an overview of the topics detailed in this document. This Summary is not intended to limit the scope of the claims.

The embodiment of the invention provides a reflective film and a preparation method thereof, in particular to an all-solid reflective film and a preparation method thereof. The all-solid reflective film of the embodiment of the present invention is an all-solid crystal photonic film, which has the advantages of all solid state, flexibility, shape, high reflectivity and reflective band gap, and can be widely applied to a series of optical devices. Products such as lasers, laser goggles, reflective displays, electronic paper, smart windows, and other optics.

In a first aspect, an embodiment of the present invention provides an all-solid reflective film, wherein the all-solid reflective film is an all-solid reflective film, the reflective film includes a polymer matrix having a microcavity, and is filled in the microcavity. A filling medium, wherein the microcavity in the reflective film exhibits a helical structure.

In an embodiment of the invention, the thickness of the reflective film is not less than 5 times the central wavelength of the wavelength band of the reflective film.

In the embodiment of the present invention, the all-solid reflective film forms a photonic crystal by polymer and liquid crystal self-assembly, and forms a stable photonic crystal microcavity structure after polymerization, and the microcavity has directionality, and only forms a refractive index in the direction of the helical axis of the liquid crystal molecule. Periodically changing microcavities.

The formation of the microcavity is due to the self-assembly of the liquid crystal molecules under the action of the orientation, and the spiral structure is reproduced by the action of the polymer.

The following is a preferred technical solution of the embodiments of the present invention, but is not intended to limit the technical solutions provided by the present invention. The following preferred technical solutions can better achieve and implement the technology of the present invention. Purpose and beneficial effects.

Preferably, the helical structure is identical to the molecular arrangement of the cholesteric liquid crystal.

In the cholesteric liquid crystal, the molecules are flat and arranged in layers. The molecules in the layer are parallel to each other. The long axis of the molecule is parallel to the plane of the layer. The long axis of the molecules in different layers changes slightly, and the spiral structure is arranged along the normal direction of the layer. .

In the cholesteric liquid crystal, the distance between the two layers in which the molecular arrangement is completely the same is called the pitch of the cholesteric liquid crystal.

Preferably, the microcavity which appears as a spiral structure in the reflective film is obtained by removing cholesteric liquid crystal dispersed in the polymer.

Preferably, in the reflective film, the spiral structure exhibited by the microcavity is a right-handed structure or a left-handed structure. The "right-handed structure" refers to: the micro-cavity arrangement rotation direction is right-handed; the "left-hand rotation structure" means that the micro-cavity arrangement rotation direction is left-handed.

Herein, the specific kind of the filling medium is not limited, as long as it is a curable colorless substance, for example, it may be a UV curing glue and a heat curing glue, etc., and those skilled in the art can select a suitable filling medium to adapt to different needs. Application environment.

Herein, the reflection band width of the reflective film (also referred to as the reflection band gap line width) is adjustable. The reflection band gap depends on the difference in refractive index between the polymer and the filling medium and the size of the film microcavity period (ie, the pitch).

Herein, according to the HTP*P*C=1 formula, wherein the HTP value represents a constant of the twisting force of the chiral agent to the liquid crystal molecules, P represents a pitch, and C represents a chiral agent concentration. The concentration of the chiral agent affects the pitch of the microcavity of the film, which directly affects the color of the film.

In the embodiment of the present invention, the forbidden line width and position of the reflective film can be realized by changing the microcavity period and the filling medium, and the reflective film of the embodiment of the invention has strong resistance to external interference (for example) Electromagnetic field, light field, stress, etc.).

As a preferred technical solution of the reflective film according to the embodiment of the present invention, the filling medium is any one or a combination of two of a UV curable adhesive or a thermosetting adhesive.

In an embodiment of the invention, the reflective film may be a single layer reflective film or a composite reflective film.

In the embodiment of the present invention, the composite reflective film is formed by laminating at least one single-layer reflective film, and is preferably formed by laminating two single-layer reflective films.

As a preferred technical solution of the reflective film according to the embodiment of the present invention, the composite reflective film is formed by laminating two single-layer reflective films, and the microcavity in the single-layer reflective film exhibits a right-handed structure, and The microcavity in a single layer of reflective film exhibits a left-handed structure;

Preferably, the composite reflective film is formed by laminating two single-layer reflective films, and the polymers in the two single-layer reflective films are the same.

In a second aspect, an embodiment of the present invention provides a method of preparing an all-solid reflective film according to the first aspect, the method comprising the steps of:

(1) coating an alignment agent on the first substrate, annealing, and rubbing orientation to obtain a first composite layer having an alignment layer;

(2) coating an alignment agent on the second substrate, annealing, and rubbing orientation to obtain a second composite layer having an alignment layer;

(3) forming a liquid crystal cell by the first composite layer and the second composite layer, and the substrate (the first substrate and the second substrate) are both located outside, and the alignment layer and the second composite layer in the first composite layer are The orientation layer is in an anti-parallel orientation, and a spacer is disposed between the first composite layer and the second composite layer to ensure that the liquid crystal cell has an opening;

(4) injecting a cholesteric liquid crystal, a photoinitiator, and a polymer monomer into the liquid crystal cell obtained in the step (3);

(5) polymerizing a polymer monomer;

(6) Soaking and dissolving using a solvent, then taking out the film material and drying;

(7) A filler is injected into the film layer obtained after drying, and solidified to obtain a reflective film.

In the embodiment of the present invention, the "anti-parallel orientation" in the step (3) means that the rubbing direction of the alignment layer in the first composite layer is parallel to and opposite to the rubbing direction of the alignment layer in the second composite layer, and the formed liquid crystal The cell is a liquid crystal cell in an anti-parallel orientation (ie, the opposite direction of the rubbing orientation direction).

In the step (3) of the embodiment of the present invention, the opening direction of the liquid crystal cell is not limited, and may be a plurality of openings on four sides or two opposite sides.

In the method of the embodiment of the present invention, the cholesteric liquid crystal in the step (4) is self-assembled in an anti-parallel oriented liquid crystal cell to form a one-dimensional photonic crystal structure, and the polymer monomer is aligned and stabilized with the liquid crystal molecules.

In the method of the embodiment of the present invention, after exposure by the step (5), the first polymer adjacent to the first composite layer and the photo-alignment agent are photo-triggered, and the polymer monomer surrounds the cholesteric phase. The liquid crystal is polymerized to obtain a polymer; the alignment agent orients the cholesteric liquid crystal molecules and crosslinks with the polymer.

In the method of the embodiment of the present invention, after the soaking and dissolving in the step (6), the taken-out film material has been separated from the substrate and the unreacted polymer monomer and the cholesteric liquid crystal have been removed. Only the polymer matrix with microcavities remains.

In the method of the embodiment of the present invention, the filler described in the step (7) is a curable filler, and after being cured, is converted into a filling medium.

As a preferred technical solution of the method,

The step (1) is replaced by the step (1)': the first substrate is coated with an SD1 photo-alignment agent, baked at 60 ° C for 2 min, and then the substrate is placed in a linearly polarized ultraviolet light environment of 365 nm to obtain an oriented layer. First composite layer;

Preferably, the step (2) is replaced by the step (2)': coating the second substrate with the SD1 photo-alignment agent, baking at 60 ° C for 2 min, and then placing the substrate in a linearly polarized ultraviolet light environment of 365 nm to obtain a second composite layer having an alignment layer;

Preferably, the step (3) is replaced by the step (3)': the first composite layer and the second composite layer are stacked in anti-parallel, separated by a spacer to form a liquid crystal cell;

Preferably, the apparatus independently employed in the coating of the step (1), the step (1)', the step (2) and the step (2)' is a homogenizer or a coating machine.

Preferably, the aligning agent in the step (1) and the step (2) is PI.

Preferably, the annealing temperature of step (1) and step (2) is 200 °C.

Preferably, the first substrate and the step (2) and the step (2) of the step (1), the step (1) of the second substrate comprise any one of a glass, a flat surface metal substrate or a PET plate. Or a combination of at least two, but not limited to the substrates listed above, other substrates commonly used in the art can also be used in embodiments of the present invention.

Preferably, the first alignment layer of the step (1) and the second alignment layer of the step (2) are both polyimide layers.

In the embodiment of the present invention, the spacers in the step (3) and the step (3) are not limited, and may be all materials that are not easily deformed, including but not limited to polyethylene terephthalate PET sheets or silicon. Any one or combination of two.

Preferably, the cholesteric liquid crystal in the step (4) is any one of a left-handed cholesteric liquid crystal or a right-handed cholesteric liquid crystal.

Herein, the "right-handed cholesteric liquid crystal" means that the direction of rotation of the molecules in the cholesteric liquid crystal is right-handed; the "left-handed cholesteric liquid crystal" means that the direction of rotation of the molecules in the cholesteric liquid crystal is left-handed .

Preferably, the cholesteric liquid crystal of the step (4) is composed of a nematic liquid crystal and a chiral agent.

Herein, the mass ratio of the nematic liquid crystal to the chiral agent is not limited, and the concentration ratio may be no array, the concentration ratio is different, and the corresponding film colors are different.

Herein, the specific model of the nematic liquid crystal is not limited, and may be, for example, a nematic liquid crystal E7 or other type of nematic liquid crystal.

Herein, the specific model of the chiral agent is not limited, and may be, for example, chiral agents R5011 and S5011.

Preferably, the photoinitiator of step (4) comprises any one of Darocur 1173, Irgacure 2100 or Irgacure 2959, but is not limited to the above-exemplified photoinitiators, other light commonly used in the art to achieve the beneficial effects herein. Initiators can also be used in embodiments of the invention.

Preferably, the polymer monomer in the step (4) comprises any one of RM257, RM82, RM006, RM021 or RM010 or a combination of at least two, but is not limited to the above-exemplified polymer monomers, and other achievable Polymeric monomers commonly used in the art for the beneficial effects herein are also useful in embodiments of the invention.

Preferably, the polymer monomer is a mixture of RM257, RM82, RM006, RM021 and RM010.

In this paper, the molecular structure of RM257 is as in Formula I:

In this paper, the molecular structure of RM82 is as in Formula II:

In this paper, the molecular structure of RM006 is as in Formula III:

In this paper, the molecular structure of RM021 is as in Formula IV:

In this paper, the molecular structure of RM010 is as in Formula V:

Preferably, the mass ratio of RM257, RM82, RM006, RM021 and RM010 is 30:15:20:20:15.

Preferably, a light absorbing agent is further added to the polymer monomer in the step (4), and the light absorbing agent is preferably an ultraviolet absorbing agent.

Preferably, the mass ratio of the cholesteric liquid crystal, the photoinitiator and the polymer monomer in the step (4) is (74 to 79): 1: (20 to 25).

Preferably, the step (4) further comprises the steps of mixing the cholesteric liquid crystal, the photoinitiator and the polymer monomer, heating and stirring before the injecting.

Preferably, the heating temperature is 70 ° C and the stirring time is 10 min or more.

Preferably, the manner in which the polymer monomer is polymerized as described in step (5) includes the manner of exposure or the manner in which the initiator initiates polymerization, preferably in the form of exposure.

Preferably, the method of polymerizing the polymer monomer in the step (5) is: from the side of the first composite layer Exposure.

Preferably, the exposure is ultraviolet light exposure.

Preferably, the solvent in the step (6) comprises any one of toluene, n-hexane or cyclohexane or a combination of at least two, but is not limited to the solvents listed above, and other commonly used in the art can dissolve the practice of the invention. The solvent of the unreacted polymer monomer and the cholesteric liquid crystal of the scheme, without dissolving the polymer, can also be used in the embodiment of the present invention.

When the embodiment of the present invention adds an ultraviolet absorber to a polymer monomer and exposes it by ultraviolet light exposure, the effect of exposure can be promoted.

As a preferred technical solution of the method of the embodiment of the present invention, after performing step (6), without performing step (7), the following steps are performed: repeating at least one step (1)-(6) in sequence to obtain at least 2 a dried film layer, and then injecting a filler into the at least two dried film layers, and bonding at least two film layers filled with the filler, and curing, to obtain at least two layers of single A composite reflective film in which a layer of reflective film is bonded.

Preferably, the filler is injected in such a manner that the filler is applied to the film and the filler automatically enters the microcavity.

As a further preferred technical solution of the method of the embodiment of the present invention, after the step (6) is carried out, the step of performing the following steps without performing the step (7): repeating the steps (1) to (6) once, obtaining two baking The dried film layer is then filled into the two dried film layers, and the two film layers filled with the filler are bonded and cured to obtain a two-layer single-layer reflective film. A composite reflective film.

Preferably, in the process of preparing a composite reflective film formed by laminating two single-layer reflective films, the direction of rotation of the molecules in the cholesteric liquid crystal used in the step (4) is repeated and the cholesteric phase in the step (4) The direction of rotation of the molecules in the liquid crystal is different.

Preferably, in the process of preparing the composite reflective film formed by laminating two single-layer reflective films, the cholesteric liquid crystal used in repeating the step (4) is a right-handed cholesteric liquid crystal, and the step (4) is as described in the step (4). The cholesteric liquid crystal is a left-handed cholesteric liquid crystal;

Preferably, in the process of preparing a composite reflective film formed by laminating two single-layer reflective films, the cholesteric liquid crystal used in the repeating step (4) is a left-handed cholesteric liquid crystal, and the step (4) The 甾 phase liquid crystal is a right-handed cholesteric liquid crystal;

In the embodiment of the present invention, in the process of preparing the composite reflective film formed by laminating two single-layer reflective films, the polymer used in the step (4) may be the same as the polymer described in the step (4), or Differently, the ratio of the specific components in the polymer is not limited, and those skilled in the art can appropriately select according to the needs.

Preferably, in the process of preparing a composite reflective film obtained by laminating two single-layer reflective films, the refractive index of the filler injected into the two dried film layers is different.

(1) The embodiment of the present invention combines the self-assembly property of cholesteric liquid crystal with the characteristics of polymer film formation to prepare an ordered microcavity structure, which has good research value and use value, more specifically The unreacted polymer monomer and the cholesteric liquid crystal are removed by soaking to obtain a polymer matrix having a microcavity, and then a filler is injected into the obtained film material to be solidified, thereby finally obtaining a reflective film excellent in performance, and the reflective film is obtained. A polymer matrix having a microcavity structure, and a filling medium filled therein are included.

(2) The reflective film of the embodiment of the present invention has the advantages of being all solid, flexible, moldable, and high in reflectivity, and the reflective film can be completely separated from the substrate, that is, a substrate-free reflective film can be obtained.

(3) In the embodiment of the present invention, the type of the filling medium is adjustable. By replacing the filling medium and the period of the microcavity of the film, the forbidden band width and position of the reflective film can be adjusted, and a narrow line width and a high reflectance can be obtained. Reflective film.

(4) The reflective film in the embodiment of the present invention may be a single-layer reflective film or a composite reflective film. The composite reflective film is prepared by a plurality of single-layer reflective films by a multilayer bonding technique to obtain two or more reflective films, which can realize a wide-band reflection function.

In the embodiment of the present invention, the reflectance of the single-layer reflective film is less than 50%, and the reflectance of the composite reflective film is greater than 80%.

Other aspects will be apparent upon reading and understanding the drawings and detailed description.

DRAWINGS

1 is a schematic structural view of a double-layered reflective film according to Embodiment 1 of the present invention, wherein 11 represents a first single-layer reflective film, 12 represents a second single-layer reflective film, and 1 represents a double-layer reflective film;

2 is a schematic structural view of a four-layer reflective film according to Embodiment 2 of the present invention, wherein 21 represents a first single-layer reflective film, 22 represents a second single-layer reflective film, 23 represents a third single-layer reflective film, and 24 represents a fourth A single-layer reflective film, 2 represents a four-layer reflective film.

Detailed ways

The technical solutions of the present disclosure will be further described below in conjunction with the accompanying drawings and specific embodiments.

Example 1

The embodiment provides a reflective film, in particular, an all-solid high-reflectivity double-layer reflective film, which is formed by laminating two single-layer reflective films, and the two single-layer reflective films are respectively named as the first single-layer reflection. a film and a second single layer reflective film.

The first single-layer reflective film is composed of a polymer matrix having a microcavity, and a filling medium (cured NOA 81 ultraviolet curable gel) filled in the microcavity, wherein the microcavity exhibits a right-handed structure;

The second single-layer reflective film is composed of a polymer matrix having a microcavity, and a filling medium (cured NOA 81 ultraviolet curable gel) filled in the microcavity, wherein the microcavity exhibits a left-handed structure;

1 is a schematic structural view of a double-layered reflective film of the present embodiment, wherein 11 represents a first single layer reflection Film; 12 represents a second single layer reflective film, and 1 represents a double layer reflective film.

Preparation:

First, the preparation of the first single layer of reflective film:

(1) Applying a polyimide liquid on a glass substrate, annealing at 200 ° C, and performing rubbing orientation using a high-speed rotating flannel to obtain a first composite layer composed of glass and an oriented polyimide layer;

(2) coating a polyimide substrate on a glass substrate, annealing at 200 ° C, and performing rubbing orientation using a high-speed rotating flannel to obtain a second composite layer composed of glass and an oriented polyimide layer;

(3) forming the first composite layer and the second composite layer to form a liquid crystal cell, wherein the substrate is located outside, the alignment layer in the first composite layer and the alignment layer in the second composite layer are in an anti-parallel orientation, and a PET layer spacer is disposed between the first composite layer and the second composite layer to ensure that the liquid crystal cell has an opening;

(4) mixing the cholesteric liquid crystal, the photoinitiator and the polymer monomer in a mass ratio of 74:25:1, heating to 70 ° C, stirring for 10 min, mixing them uniformly, and then injecting the liquid crystal obtained in the step (3) a box (which is an anti-parallel oriented liquid crystal cell),

Wherein, the cholesteric liquid crystal is composed of a nematic liquid crystal E7 and a chiral agent R5011 in a mass ratio of 98.4:1.6; the polymer monomers are RM257, RM82, RM006, RM021 and RM010 by 30:15:20:20:15 a mixture of mass ratios;

(5) performing exposure from the side of the first composite layer to polymerize the polymer monomer;

(6) Soaking and dissolving in a solvent, the unreacted polymer monomer and the cholesteric liquid crystal are dissolved in the solvent, leaving only the polymer matrix having the microcavity, then taking out the film material, drying, and obtaining the dried Film layer

(7) Injecting NOA 81 ultraviolet curable adhesive into the dried film layer and entering the microcavity to obtain a first single layer reflective film.

Second, the preparation of the second single layer reflective film:

(I) repeating step (1) to obtain a first composite layer composed of glass and an oriented polyimide layer;

(II) repeating step (2) to obtain a second composite layer composed of glass and an oriented polyimide layer;

(III) repeating step (3) to form a liquid crystal cell;

(IV) mixing the cholesteric liquid crystal, the photoinitiator and the polymer monomer in a mass ratio of 74:25:1, heating to 70 ° C, stirring for 10 min, mixing them uniformly, and then injecting the anti-step (3) In a parallel-oriented liquid crystal cell,

Wherein, the cholesteric liquid crystal is composed of a nematic liquid crystal E7 and a chiral agent S5011 in a mass ratio of 98.4:1.6; the polymer monomers are RM257, RM82, RM006, RM021 and RM010 by 30:15:20:20:15 a mixture of mass ratios;

(V) repeating step (5) to polymerize the polymer monomer;

(VI) repeating step (6) to obtain a dried film layer;

(VII) Step (7) is repeated to obtain a second single-layer reflective film.

Third, the preparation of double-layer reflective film:

The first single-layer reflective film and the second single-layer reflective film roll are bonded to each other and cured to obtain a double-layered reflective film.

In this embodiment, a commonly used ultraviolet lamp is used as a curing light source for curing, and the center wavelength is 365 nm (optionally 290 nm to 390 nm).

In the present embodiment, the initiator selected is Irgacure 2100, Irgacure 2959 or Darocur 1173.

In this embodiment, toluene is used as a solvent (a solvent such as n-hexane or cyclohexane may also be used).

The double-layered reflective film of this embodiment is a two-dimensional reflective film.

The double-layered reflective film obtained in the present example was examined, and the results showed that the center of the forbidden band was at 645 nm, the line width was 68 nm, and the reflectance was 82%. Optimized to achieve more than 90%.

Example 2

The embodiment provides a reflective film, in particular, an all-solid high-reflectivity four-layer reflective film, which is formed by bonding four single-layer reflective films, and the four single-layer reflective films are respectively named as the first single-layer reflection. A film, a second single layer reflective film, a third single layer reflective film, and a fourth single layer reflective film.

The third single-layer reflective film is composed of a polymer matrix having a microcavity, and a filling medium (cured NOA 81 ultraviolet curable gel) filled in the microcavity, wherein the microcavity exhibits a right-handed structure;

The fourth single-layer reflective film is composed of a polymer matrix having a microcavity, and a filling medium (cured NOA 81 ultraviolet curable gel) filled in the microcavity, wherein the microcavity exhibits a left-handed structure;

2 is a schematic structural view of a four-layer reflective film of the present embodiment, wherein 21 represents a first single-layer reflective film, 22 represents a second single-layer reflective film, 23 represents a third single-layer reflective film, and 24 represents a fourth single-layer reflective film. Reflective film, 2 represents a four-layer reflective film.

Preparation:

First, the preparation of the first single layer of reflective film:

(3) forming the first composite layer and the second composite layer to form a liquid crystal cell, wherein the substrate is located outside, the alignment layer in the first composite layer and the alignment layer in the second composite layer are in an anti-parallel orientation, and First complex a PET layer spacer between the layer and the second composite layer to ensure that the liquid crystal cell has an opening;

Wherein, the cholesteric liquid crystal is composed of a nematic liquid crystal E7 and a chiral agent R5011 in a mass ratio of 98.2:1.8; the polymer monomers are RM257, RM82, RM006, RM021 and RM010 by 30:15:20:20:15 a mixture of mass ratios;

Second, the preparation of the second single layer reflective film:

Steps (1) to (7) are sequentially repeated except that the cholesteric liquid crystal in the step (4) is composed of a nematic liquid crystal E7 and a chiral agent S5011 in a mass ratio of 98.2:1.8.

Third, the preparation of the third single layer reflective film:

Steps (1) to (7) are sequentially repeated except that the cholesteric liquid crystal in the step (4) is composed of a nematic liquid crystal E7 and a chiral agent R5011 in a mass ratio of 98.4:1.6.

Fourth, the preparation of the fourth single layer reflective film:

Steps (1) to (7) are sequentially repeated except that the cholesteric liquid crystal in the step (4) is composed of a nematic liquid crystal E7 and a chiral agent S5011 in a mass ratio of 98.4:1.6.

Fifth, the preparation of four layers of reflective film:

The first single-layer reflective film, the second single-layer reflective film, the third single-layer reflective film, and the fourth single-layer reflective film roll are bonded to each other and cured to obtain a four-layer reflective film.

The four-layer reflective film obtained in the present example was tested, and the results showed that the center of the forbidden band was at 615 nm, the line width was 140 nm, and the reflectance was 80%. Optimized to achieve more than 90%.

Example 3

This embodiment provides a reflective film, specifically an all-solid high reflectivity single-layer reflective film.

The reflective film is composed of a polymer matrix having a microcavity, and a filling medium (cured NOA 81 ultraviolet curable gel) filled in the microcavity, wherein the microcavity exhibits a right-handed structure;

Preparation:

(7) Injecting NOA 81 ultraviolet curable adhesive into the dried film layer, and entering into the microcavity, and solidifying to obtain a single layer reflective film.

The single-layer reflective film obtained in the present example was examined, and the results showed that the film had a uniform color and a reflectance of more than 80%.

Example 4

Other preparation methods and conditions were the same as in Example 3 except that the cholesteric liquid crystal was replaced by a mass ratio of the nematic liquid crystal E7 to the chiral agent S5011 of 98.4:1.6.

The single-layer reflective film obtained in this example was examined, and it was found that the film reflected red left circularly polarized light.

Example 5

The orientation is performed by using a photo-alignment agent to uniformly align the liquid crystal molecules to realize a single-domain device, which greatly reduces the scattering of photons in the device, and the reflectance can reach more than 90%. The specific preparation process is as follows:

The liquid crystal molecules are aligned by a photo-alignment agent (SD1). The photo-alignment agent replaces the polyimide. Since the photo-alignment agent does not require surface rubbing orientation, the disclination line of the liquid crystal mixture in the liquid crystal is greatly reduced. The usual rubbing orientation causes the liquid crystal cholesteric liquid crystal to form a multi-domain structure, which causes a certain misalignment between each crystal domain, thereby increasing the scattering of the device. The orientation by the photo-alignment agent enables the cholesteric liquid crystal to realize a single domain structure in the liquid crystal cell, thereby greatly reducing scattering inside the device.

The specific implementation is as follows:

The SD1 alignment agent was applied to a glass substrate, baked at 60 ° C for 2 minutes, and then the substrate was placed in a linearly polarized ultraviolet light environment of 365 nm for 5 minutes, and the ultraviolet light power was 10 mW/cm ² . The two oriented glass substrates are stacked in anti-parallel and separated by a spacer to form a liquid crystal cell. The subsequent steps are the same as in the first embodiment.

As can be seen from the above examples, the two-layer film of the embodiment of the present invention has high reflectance and all-solid state characteristics.

The Applicant claims that the detailed description of the present disclosure is made by the above-described embodiments, but the present disclosure is not limited to the detailed methods described above, that is, it does not mean that the present disclosure must rely on the detailed methods described above. It should be apparent to those skilled in the art that any modifications of the present disclosure, equivalent substitution of the various materials of the present disclosure, and addition of auxiliary components, selection of specific manners, etc., are all within the scope of the present disclosure.

Claims

An all-solid reflective film comprising a polymer matrix having microcavities, and a filling medium filled in the microcavities;

Wherein, the microcavity in the reflective film exhibits a spiral structure.
The reflective film according to claim 1, wherein the thickness of the reflective film is not less than 5 times the center wavelength of the wavelength band of the reflective film.
The reflective film according to claim 1 or 2, wherein the helical structure is the same as the molecular arrangement of the cholesteric liquid crystal.
The reflective film according to any one of claims 1 to 3, wherein the microcavity exhibiting a spiral structure in the reflective film is obtained by removing cholesteric liquid crystal dispersed in a polymer;

Preferably, in the reflective film, the spiral structure exhibited by the microcavity is a right-handed structure or a left-handed structure.
The reflective film according to any one of claims 1 to 4, wherein the filling medium comprises any one or a combination of two of an ultraviolet curable adhesive or a thermosetting adhesive.
The reflective film according to any one of claims 1 to 5, wherein the reflective film is a single-layer reflective film or a composite reflective film;

Preferably, the composite reflective film is formed by laminating at least one single-layer reflective film, preferably by laminating two single-layer reflective films;

Preferably, the composite reflective film is formed by laminating two single-layer reflective films, and the microcavity in the single-layer reflective film exhibits a right-handed structure, and the micro-cavity in the other single-layer reflective film is presented. Left-handed structure;

Preferably, the composite reflective film is formed by laminating two single-layer reflective films, and the polymers in the two single-layer reflective films are the same.
A method of producing a reflective film according to any one of claims 1 to 6, comprising the steps of:

(1) coating an alignment agent on the first substrate, annealing, and rubbing orientation to obtain a first composite layer having an alignment layer;

(2) coating an alignment agent on the second substrate, annealing, and rubbing orientation to obtain a second composite layer having an alignment layer;

(3) forming the first composite layer and the second composite layer to form a liquid crystal cell, wherein the substrate is located outside, the alignment layer in the first composite layer and the alignment layer in the second composite layer are in an anti-parallel orientation, and a spacer between the first composite layer and the second composite layer to ensure that the liquid crystal cell has an opening;

(4) injecting a cholesteric liquid crystal, a photoinitiator, and a polymer monomer into the liquid crystal cell obtained in the step (3);

(5) polymerizing a polymer monomer;

(6) Soaking and dissolving using a solvent, then taking out the film material and drying;

(7) A filler is injected into the film layer obtained after drying, and solidified to obtain a reflective film.
The method according to claim 7, wherein the step (1) is replaced by the step (1)': the first substrate is coated with an SD1 photo-alignment agent, baked at 60 ° C for 2 min, and then the substrate is placed at a line of 365 nm. Exposing in a polarized ultraviolet light environment to obtain a first composite layer having an alignment layer;

Preferably, the step (2) is replaced by the step (2)': coating the second substrate with the SD1 photo-alignment agent, baking at 60 ° C for 2 min, and then placing the substrate in a linearly polarized ultraviolet light environment of 365 nm to obtain a second composite layer having an alignment layer;

Preferably, the step (3) is replaced by the step (3)': the first composite layer and the second composite layer are stacked in anti-parallel, separated by a spacer to form a liquid crystal cell;

Preferably, the apparatus independently used in the coating of the step (1), the step (1), the step (2), and the step (2) is a homogenizer or a coating machine;

Preferably, the aligning agent in step (1) and step (2) is PI;

Preferably, the annealing temperature of step (1) and step (2) is 200 ° C;

Preferably, the first substrate and the step (2) and the step (2) of the step (1), the step (1)' The second substrate comprises any one of glass, a flat surface metal substrate or a PET plate or a combination of at least two;

Preferably, the orientation layer of step (1) and the orientation layer of step (2) are both polyimide layers;

Preferably, the spacer (3) and the step (3)' comprise the spacer comprising any one or a combination of two of polyethylene terephthalate PET sheets or silicon balls;

Preferably, the cholesteric liquid crystal in the step (4) is any one of a right-handed cholesteric liquid crystal or a left-handed cholesteric liquid crystal;

Preferably, the cholesteric liquid crystal of the step (4) is composed of a nematic liquid crystal and a chiral agent;

Preferably, the photoinitiator of step (4) comprises any one of Darocur 1173, Irgacure 2100 or Irgacure 2959;

Preferably, the polymer monomer in the step (4) comprises any one of RM257, RM82, RM006, RM021 or RM010 or a combination of at least two, preferably a mixture of RM257, RM82, RM006, RM021 and RM010;

Preferably, the mass ratio of RM257, RM82, RM006, RM021 and RM010 is 30:15:20:20:15;

Preferably, the polymer monomer in the step (4) is further added with a light absorbing agent, and the light absorbing agent is preferably an ultraviolet absorbing agent;

Preferably, the mass ratio of the cholesteric liquid crystal, the photoinitiator and the polymer monomer in the step (4) is (74-79): 1: (20-25);

Preferably, the step (4) further comprises the steps of mixing the cholesteric liquid crystal, the photoinitiator and the polymer monomer, heating and stirring before the injecting;

Preferably, the heating temperature is 70 ° C, and the stirring time is 10 min or more;

Preferably, the manner of polymerizing the polymer monomer in the step (5) includes a method of exposure or an initiator. The manner of initiating the polymerization, preferably the manner of exposure;

Preferably, the method of polymerizing the polymer monomer in the step (5) is: performing exposure from the side of the first composite layer;

Preferably, the exposure is ultraviolet light exposure;

Preferably, the solvent in the step (6) comprises any one of toluene, n-hexane or cyclohexane or a combination of at least two.
The method according to claim 7 or 8, further comprising, after performing step (6), performing the following steps without repeating step (7): repeating at least one of steps (1)-(6) in sequence to obtain at least 2 a dried film layer, and then injecting a filler into the at least two dried film layers, and bonding at least two film layers filled with the filler, and curing, to obtain at least two layers of single a composite reflective film formed by laminating reflective films;

Preferably, the filler is injected by applying a filler to the film and the filler automatically enters the microcavity.
The method according to any one of claims 7 to 9, wherein the steps (1) to (6) are repeated once to obtain two dried film layers, and then respectively to the two dried films. a filler is injected into the layer, and two film layers filled with the filler are bonded and cured to obtain a composite reflective film obtained by laminating two single-layer reflective films;

Preferably, in the process of preparing a composite reflective film formed by laminating two single-layer reflective films, the direction of rotation of the molecules in the cholesteric liquid crystal used in the step (4) is repeated and the cholesteric phase in the step (4) The direction of rotation of the molecules in the liquid crystal is different;

Preferably, in the process of preparing the composite reflective film formed by laminating two single-layer reflective films, the cholesteric liquid crystal used in repeating the step (4) is a right-handed cholesteric liquid crystal, and the step (4) is as described in the step (4). The cholesteric liquid crystal is a left-handed cholesteric liquid crystal;

Preferably, in the process of preparing a composite reflective film formed by laminating two single-layer reflective films, the cholesteric liquid crystal used in the repeating step (4) is a left-handed cholesteric liquid crystal, and the step (4) The 甾 phase liquid crystal is a right-handed cholesteric liquid crystal;

Preferably, in the process of preparing a composite reflective film formed by laminating two single-layer reflective films, the polymer used in the repeating step (4) is the same as the polymer described in the step (4);

Preferably, in the process of preparing a composite reflective film obtained by laminating two single-layer reflective films, the refractive index of the filler injected into the two dried film layers is different.