Composition, holographic optical element, projection device, display device, and vehicle

Abstract

The embodiment of the invention discloses a composition, a holographic optical element, a projection device, display equipment and a vehicle, and mainly aims to solve the problems of photosensitizer failure, fogging and / or early thermal polymerization of a monomer in a high-temperature / high-pressure treatment process of a raw material of a holographic photopolymer. The visible light photosensitizer of the composition adopts cyanines, phenothiazine, benzothiophene, anthraquinone, phenoxazine, thioxanthone and other structures as cations C < n + >, and adopts one or a combination of more of alkyl chains, halogen, phosphorus, oxygen, nitrogen, sulfur and the like as anions A < n->, so that the redox potential of the visible light photosensitizer is adjusted; the visible light photosensitizer in a ground state and the coinitiator matched with the visible light photosensitizer are more stable. Therefore, when the composition is subjected to high-temperature / high-pressure process treatment and the like, photosensitizer failure and fogging cannot occur, monomers cannot be promoted to polymerize in advance, and a holographic grating with relatively high diffraction efficiency is ensured to be exposed subsequently.

Description

Technical Field

[0001] The present application relates to the technical field of holography, and particularly relates to a composition, a holographic optical element, a projection device, a display device and a vehicle. Background Art

[0002] Holography, also known as holographic photography, refers to the technology of recording the amplitude and phase distribution of light waves on a holographic recording medium and reproducing a three-dimensional image of an object. Holographic recording media are rich and diverse. Among them, holographic photopolymers are widely used in high-tech fields such as high-end anti-counterfeiting, holographic data storage, and holographic optical element manufacturing due to their advantages such as flexible processing, wide photosensitive range, and high diffraction efficiency. In order to promote holographic photopolymers to broader application fields, such as Augmented Reality (AR) and Head-up Display (HUD), it is required that holographic photopolymers must take into account excellent optical quality, high diffraction efficiency, and good heat resistance.

[0003] For application scenarios such as AR and HUD, due to optical design and the angles of different types of glass surfaces, it is required that the raw materials of holographic photopolymers undergo special and stringent process treatments (high temperature / high pressure) to form holographic optical elements (HOEs), while retaining excellent diffraction efficiency, bleachability, photosensitivity, etc. of the holographic optical elements. This is to ensure that when using this holographic optical element for holographic recording, a grating with high diffraction efficiency can be formed with a very low exposure dose, and after exposure, the holographic optical element can be bleached in a relatively simple manner.

[0004] However, the excellent bleachability and photosensitivity of the raw materials of holographic photopolymers mean that they have a high degree of instability. Therefore, during the preparation process of HOEs, stringent process treatments (high temperature / high pressure) will cause side reactions such as the failure (fading) of photosensitizers, fogging, or thermal polymerization of monomers to occur before the HOEs are applied to holographic recording. Furthermore, this leads to problems such as the inability to expose a grating in the subsequent exposure process, no diffraction efficiency, and deteriorated optical performance. Therefore, it is particularly important that the raw materials of holographic photopolymers maintain high photosensitivity and bleachability during the process treatment (high temperature / high pressure), and the monomers do not participate in side reactions, that is, it is required that the photopolymer materials have good stability. Summary of the Invention

[0005] Embodiments of the present application provide a composition, a holographic optical element, a projection device, a display device, and a vehicle, mainly aiming to solve the problems of photosensitizer failure (fading), fogging, and / or premature thermal polymerization of monomers during the process of processing (high temperature / high pressure) the raw materials of holographic photopolymers.

[0006] To achieve the above object, the embodiments of the present application adopt the following technical solutions:

[0007] In a first aspect, embodiments of the present application provide a composition, which includes: a visible light photosensitizer, a co-initiator, a matrix polymer, and at least one monomer; wherein, the general formula of the visible light photosensitizer can be expressed as: Cn + An - . Cn + represents a cation, and Cn + includes one or more structures selected from cyanine, phenothiazine, benzothiophene, anthraquinone, phenoxazine, thioxanthone; An - represents an anion, and An - includes one or more of linear alkyl, halogen, phosphorus, oxygen, nitrogen, sulfur, boron, metal ions.

[0008] In the above embodiment, biological dyes such as cyanine, phenothiazine, benzothiophene, anthraquinone, phenoxazine, thioxanthone are used as the cation Cn + of the visible light photosensitizer, and one or more combinations of alkyl chains, halogens, phosphorus, oxygen, nitrogen, sulfur, metal ions, etc. are used as the anion An - of the visible light photosensitizer. Through the combination of such a cation Cn + and an anion An - , the adjustment of the redox potential of the visible light photosensitizer is realized, so that the visible light photosensitizer and the co-initiator paired with it in the composition are more stable in the ground state (the state before exposure). In this way, when the composition is subjected to process treatments such as high temperature / high pressure to form a holographic optical element, since the visible light photosensitizer and the co-initiator paired with it are more stable, the phenomenon of photosensitizer failure will not occur, so high photosensitivity is still maintained, and the monomer will not be induced to polymerize prematurely or other side reactions will not occur, thus avoiding the fogging phenomenon and ensuring that a holographic grating with a high diffraction efficiency is exposed subsequently.

[0009] In combination with the first aspect, in a possible implementation manner, the refractive index of the above monomer at 405 nm is greater than 1.5.

[0010] In combination with the first aspect, in a possible implementation manner, the above monomer has the following chemical structure:

[0011]

[0012] Wherein, R1 is H or CH3; R2 is one or more of phenethyl, phenoxyethyl, o-phenylphenethoxy, 4-(1-methyl-1-phenethyl)phenoxyethyl, 2,4,6-tribromophenyl, 2,4,6-tribromophenoxyethyl, pentabromophenyl, pentabromophenoxy, naphthyl, naphthoxy, 1,3-bis(thiophen-2-ylthio)propan-2-yl, 1,3-bis((4-(phenylthio)phenyl)thio)propan-2-yl, 1,3-bis((4-bromophenyl)thio)propan-2-yl.

[0013] Combined with the first aspect, in a possible implementation manner, the co-initiator includes secondary or tertiary aliphatic or aromatic amines, alkylaryl ammonium borates, alcohols or thiol reagents, and the co-initiator has a hydrogen donor or an electron donor. It can act with a visible light photosensitizer based on the Norrish II-type photoinitiation mechanism.

[0014] Combined with the first aspect, in a possible implementation manner, the visible light photosensitizer is selected from substances with the following structural formulas:

[0015]

[0016]

[0017]

[0018] Combined with the first aspect, in a possible implementation manner, the co-initiator is selected from substances with the following structural formulas:

[0019]

[0020]

[0021]

[0022]

[0023] Combined with the first aspect, in a possible implementation manner, during the process of heating the composition from room temperature to 200 °C, the thermogravimetric loss of the composition < 1.2 wt%. It can be seen that the composition provided by the embodiments of the present application exhibits high thermal stability during the high-temperature treatment process.

[0024] Combined with the first aspect, in a possible implementation manner, after the composition is heated at 120 °C for 30 min, the change value of T 640 of the composition is less than or equal to 40%, and T 640 of the composition is less than or equal to 80%; wherein, T 640It represents the light transmittance of visible light with a wavelength of 640 nm. It can be seen that for the composition provided in the embodiments of the present application, after high-temperature treatment, the change in the light transmittance of visible light with a wavelength of 640 nm is small, and the light transmittance of visible light with a wavelength of 640 nm can reach up to 80%, indicating that it still has good absorption of visible light with a wavelength of 640 nm, and showing that the photosensitizer has not failed.

[0025] Combined with the first aspect, in a possible implementation manner, after the composition is heated at 120 °C for 30 min, the haze of the composition is less than or equal to 8%. It can be seen that for the composition provided in the embodiments of the present application, after high-temperature treatment, almost no atomization phenomenon occurs, indicating that almost no premature thermal polymerization of monomers occurs, and the composition has high thermal stability. Thus, when performing subsequent exposure treatment on it, a holographic grating with high diffraction efficiency can be exposed.

[0026] Combined with the first aspect, in a possible implementation manner, after the composition is heated at 120 °C for 30 min, the double-bond conversion rate of the composition is less than or equal to 20%. It can be seen that for the composition provided in the embodiments of the present application, after high-temperature treatment, it indicates that almost no premature thermal polymerization of monomers occurs, and the composition has high thermal stability. Thus, when performing subsequent exposure treatment on it, a holographic grating with high diffraction efficiency can be exposed.

[0027] Combined with the first aspect, in a possible implementation manner, in the ultraviolet-visible light spectrum of the composition, the position of the maximum absorption peak λmax of the composition is located at 600 nm - 660 nm.

[0028] In the second aspect, the embodiments of the present application provide a holographic optical element, including: an optical film layer, a functional film layer, and a protective layer stacked in sequence; the functional film layer includes any one of the above compositions. In these embodiments, the holographic optical element includes a thin film lens that has not been exposed and bleached.

[0029] In the third aspect, the embodiments of the present application provide a holographic optical element, including: an optical film layer, a functional film layer, and a protective layer stacked in sequence; the functional film layer is obtained by exposing a raw material film layer, and the raw material film layer includes any one of the above compositions. In these embodiments, the holographic optical element includes a thin film lens that has been exposed and bleached.

[0030] In the fourth aspect, the embodiments of the present application provide a projection device, including an image generation unit and an optical imaging module, the optical imaging module includes any one of the above holographic optical elements; the image generation unit is used to generate an imaging light beam based on image information and emit the imaging light beam, and the holographic optical element is located on the propagation path of the imaging light beam.

[0031] Fifth aspect, an embodiment of the present application provides a display device, including a processor and the above-mentioned projection device, and the processor is configured to send image information to an image generation unit.

[0032] Sixth aspect, an embodiment of the present application provides a vehicle, including a display device, a reflection element, and the above-mentioned holographic optical element; the display device is installed on the vehicle; the display device includes a processor and a projection device; the projection device includes an image generation unit and an optical imaging module; the processor is configured to send image information to the image generation unit, the image generation unit is configured to generate an imaging light beam based on the image information, and the optical imaging module is configured to project the imaging light beam; the reflection element and the holographic optical element are located on the propagation path of the imaging light beam. Exemplarily, the reflection element includes the front windshield of the vehicle.

[0033] Among them, for the technical effects brought by any one of the design manners in the second aspect to the sixth aspect, reference may be made to the technical effects brought by different design manners in the first aspect, which will not be elaborated herein. Description of the Drawings

[0034] Figure 1 Schematic diagram of anion exchange of photosensitizer in related technologies;

[0035] Figure 2 Schematic diagram of test results of the stability of the raw materials of the HOE film in related technologies;

[0036] Figure 3 Schematic diagram of the optical path in a head-up display device in an embodiment of the present application;

[0037] Figure 4 For Figure 3 Simplified optical path schematic diagram of the head-up display device shown;

[0038] Figure 5 Schematic diagram of the diffraction efficiency determination method in an embodiment of the present application;

[0039] Figure 6 Schematic diagram of test results of the transmittance of red light by the HOE film sample 1 after high-temperature treatment in an embodiment of the present application;

[0040] Figure 7 Schematic diagram of test results of the transmittance of visible light by the HOE film sample 1 before and after high-temperature treatment in an embodiment of the present application;

[0041] Figure 8 Schematic diagram of test results of the transmittance of red light by the HOE film sample 2 after high-temperature treatment in an embodiment of the present application;

[0042] Figure 9Schematic diagram of the visible light transmittance test results of the HOE thin film sample 2 before and after high-temperature treatment in the embodiments of the present application;

[0043] Figure 10 Schematic diagram of the test results of the red light transmittance of the HOE thin film sample 3 after high-temperature treatment in the embodiments of the present application;

[0044] Figure 11 Schematic diagram of the visible light transmittance test results of the HOE thin film sample 3 before and after high-temperature treatment in the embodiments of the present application. Detailed implementation manners

[0045] Next, the technical solutions in the embodiments of the present application will be described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments.

[0046] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those of ordinary skill in the art. In the present application, "at least one (layer)" means one (layer) or more than one (layer), and "more than one (layer)" means two (layers) or more than two (layers). "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone, where A and B may be singular or plural. The character " / " generally represents an "or" relationship between the associated objects before and after. "At least one (item)" or its similar expression below refers to any combination of these items, including any combination of single items or plural items. For example, at least one (item) of a, b, or c may represent: a, b, c, a and b, a and c, b and c, or a, b, and c, where a, b, and c may be single or multiple. In addition, in the embodiments of the present application, terms such as "first" and "second" do not limit the quantity and order.

[0047] In addition, in the present application, orientation terms such as "upper" and "lower" are defined relative to the orientation of the components shown in the drawings. It should be understood that these directional terms are relative concepts, and they are used for relative description and clarification, and they may change accordingly with the change of the orientation of the components placed in the drawings.

[0048] It should be noted that in the present application, words such as "exemplary" or "for example" are used to represent examples, illustrations, or explanations. Any embodiment or design solution described as "exemplary" or "for example" in the present application should not be construed as being more preferred or having more advantages than other embodiments or design solutions. Exactly speaking, using words such as "exemplary" or "for example" aims to present relevant concepts in a specific manner.

[0049] The technical terms in the embodiments of the present application are described as follows:

[0050] Holography: It refers to the technology of recording the amplitude and phase distribution of light waves on a photographic film or plate and reproducing the three-dimensional image of an object. Also known as holographic photography and holographic imaging. Holography can be used not only in the light wave band but also in electron waves, sound waves, X-rays, and microwaves. Ordinary photography can only record the amplitude (intensity) of the light reflected or transmitted by an object, so it records a two-dimensional image of the object. Holography can record not only the amplitude of light but also its phase, so it can record the depth information of an object.

[0051] Holographic recording: It refers to the method of making relevant records using holography. In the development process of holography, holographic recording materials play a very important role as its carrier. Currently, commonly used holographic recording media include silver halide emulsions, dichromated gelatin, photoresists, photopolymers (also known as photopolymer materials), photothermoplastic plastics, photorefractive crystals, liquid crystals, etc.

[0052] Holographic optical elements (HOE): They are optical elements made according to the principle of holography, usually made on photosensitive thin film materials, and are a type of diffractive optical element. Holographic optical elements mainly include holographic lenses, holographic gratings, holographic filters, holographic scanners, etc.

[0053] Diffraction efficiency: When the incident angle of the probing light satisfies the Bragg condition, the light intensity of the diffracted light of the holographic grating reaches the maximum. At this time, the incident angle is recorded as the Bragg angle, and the ratio of the diffracted light intensity to the sum of the diffracted light intensity and the transmitted light intensity is the diffraction efficiency of the grating.

[0054] Haze: Haze refers to the percentage of the transmitted light intensity deviating from the incident light by more than 2.5° in the total transmitted light intensity. The greater the haze, the lower the gloss and transparency of the film.

[0055] Transmittance: Transmittance represents the ability of light to pass through a medium, which is the percentage of the light flux passing through a transparent or translucent body to its incident light flux.

[0056] Refractive index modulation: In a holographic grating, the refractive index is distributed in a sine curve form along the grating vector direction, and the refractive index modulation is the amplitude of this sine curve.

[0057] Photosensitizer: Also known as sensitizer, sensitizing agent, and photocrosslinking agent. In a photochemical reaction, it is a substance that transfers light energy to some reactants that are insensitive to visible light to improve or expand their photosensitive properties. In the composition provided in the embodiments of the present application, the photosensitizer transfers light energy to the co-initiator to trigger the co-initiator to exert its catalytic function.

[0058] Co-initiator: A co-initiator, also known as a cocatalyst, is a substance that, in cationic polymerization of carbon-carbon double bonds, enables a Lewis acid to function catalytically as the Lewis acid alone is ineffective. In the compositions provided in the embodiments of this application, the co-initiator can catalyze the polymerization of monomers to form holographic gratings.

[0059] Cyanine dyes: Also known as Cyanine (CY) dyes, classic cyanine dyes contain two nitrogen-containing heterocycles and a conjugated chain composed of (CH)n methine groups inside the molecule, where n can be odd or even. The absorbance and fluorescence wavelength of cyanine dyes can be controlled by selecting the length of the polymethine bridge. The longer the cyanine, the higher the absorbance and emission wavelength. According to the number of carbon atoms in the chain, cyanine dyes are classified into monomethyl (CY1, n = 0), trimethyl (CY3, n = 1), pentamethyl (CY5, n = 2), and heptamethyl (CY7, n = 3) based on the methine group.

[0060] Phenothiazine: Phenothiazine is an organic aromatic compound composed of a sulfur and a nitrogen atom connecting two benzene rings (the phenothiazine nucleus), and it can also be called thiazine, dibenzo-1,4-thiazine, thiodiphenolamine, thiodiphenylamine, benzotriazine, etc.

[0061] Benzothiophene: It is mainly extracted from crude naphthalene, and can also be synthesized from styrene or ethylbenzene and hydrogen sulfide, or prepared by the condensation of thiophene and a benzene ring.

[0062] Anthraquinone: Also known as 9,10-anthraquinone, 9,10-anthracenedione.

[0063] Phenoxazine: Also known as phenazine, it can be obtained by passing aniline vapor through a red-hot tube, or by heating o-phenylenediamine and catechol in a tube, or by distilling 2-aminodiphenylamine and lead monoxide.

[0064] Thioxanthone: The English name is thioxanthone, and its Chinese aliases include 9-thioxanthone, thioxanthen-9-one, thioxanthene-9-one, etc.

[0065] As described in the background art, during the preparation of the HOE film, severe process treatments (high temperature / high pressure) can cause the photosensitizer in the HOE film to fail (fade), fog, or undergo side reactions of monomer thermal polymerization before being applied to holographic recording. Consequently, problems such as the inability to expose a grating in the subsequent exposure step, no diffraction efficiency, and deteriorated optical performance occur. Therefore, it is required that the raw materials of the HOE film maintain high photosensitivity and bleachability during the process treatment (high temperature / high pressure), and the monomers do not undergo side reactions of thermal polymerization. In subsequent holographic recording applications, a grating can be rapidly exposed to provide high diffraction efficiency. In addition, the photosensitizer in the material can be completely bleached within a short time to meet the conditions for mass production on a production line.

[0066] To achieve the above object, as Figure 1 shown, in the related art, by performing anion exchange on the photosensitizer in the raw materials of the HOE film, the small-volume steric hindrance Cl- or I- in the photosensitizer (cationic dye) is replaced with a large-volume steric hindrance fluorine-containing anion, such as PF6 - , CF3SO3-, etc. The results show that this solution helps to increase the thermal decomposition temperature of the original photosensitizer from 190 °C by about 20 - 40 °C. The mechanism may be that the anion exchange reduces the Eox (oxidation potential) of the original photosensitizer, thereby increasing the thermal decomposition temperature of the photosensitizer and improving its stability at high temperatures.

[0067] Regarding the above related art, using the photosensitizer after anion exchange as the raw material, the raw materials for preparing the HOE film are prepared, and the stability of the prepared raw materials is tested. The test results are as Figure 2 shown, where, in Figure 1At the position indicated by the dashed arrow, along the direction indicated by the arrow, each transmittance change curve corresponds to a (representing the test result of the red light photosensitizer before anion substitution before heating), b (representing the test result of the red light photosensitizer with anion substituted by C2 after heating), c (representing the test result of the red light photosensitizer with anion substituted by C1 after heating), d (representing the test result of the red light photosensitizer with anion substituted by C3 after heating), e (representing the test result of the red light photosensitizer before anion substitution after heating), f (representing the test result of the red light photosensitizer with anion substituted by C2 before heating), g (representing the test result of the red light photosensitizer with anion substituted by C1 before heating), and h (representing the test result of the red light photosensitizer with anion substituted by C3 before heating). The test results show that, compared with the original photosensitizer, it is found that after high-temperature heating, the red light-sensitive raw materials all show obvious fading, and visually, it can be seen that the color of the film material directly changes from blue to colorless. Thus, it can be known that although anion exchange can increase the thermal decomposition temperature of the photosensitizer, the thermal stability of the unexposed raw materials has not been improved. That is to say, the problem of the performance stability of the raw materials of the HOE film during the process treatment (high temperature / high pressure) has not been solved yet.

[0068] The embodiments of the present application provide a composition and a holographic optical element. The composition is specifically the raw material of the holographic optical element. The holographic optical element can be a HOE film or a HOE film lens. The HOE film can be a film material after exposure and bleaching treatment, or a film material without exposure and bleaching treatment. The HOE film lens uses the HOE film as a functional film layer. In addition to including the functional film layer, it can also include an optical film layer and a protective film. Among them, the functional film layer can be arranged between the optical film layer and the protective film. In the embodiments of the present application, by adjusting the redox potential of the photosensitizer in the composition, the stability of the photosensitizer and its paired co-initiator before exposure is improved, and it does not affect their photosensitivity during exposure and bleachability after exposure. In addition, the side reaction of monomer thermal polymerization during the process treatment (high temperature / high pressure) of the composition is also avoided, so as to ensure that a holographic grating with high diffraction efficiency can be formed during subsequent exposure.

[0069] The holographic optical element HOE provided by the embodiments of the present application can be applied to scenarios such as in-vehicle head-up display (HUD), AR glasses, holographic 3D projection, etc., to replace lenses, gratings, mirrors or more complex optical elements. Taking the application in HUD as an example, Figure 3 It is a schematic diagram of the optical path in a head-up display device, Figure 4 is Figure 3 the simplified schematic diagram of the optical path in the head-up display device shown. Combining Figure 3 and Figure 4, the head-up display device includes an image generation unit (PGU, commonly known as an optical engine) and a rear-stage optical system (mainly composed of various optical path components, such as a light diffusing element, a light reflecting element). Among them, the PGU is used to generate an optical signal according to the input electrical signal (video, image) and project the optical signal outward. The rear-stage optical system is composed of a light diffusing element, a plane mirror, a first free-form mirror, and a second free-form mirror. The light beam projected by the PGU is first received by the light diffusing element. After the light diffusing element diffuses the light beam, it is reflected by the plane mirror, the first free-form mirror, and the second free-form mirror in sequence, reaches the front windshield, and finally the front windshield reflects it to the human eye, so that the human eye can see a virtual image M in front of its field of view.

[0070] Among them, the above PGU can specifically be a display of types such as thin film transistor - liquid crystal display (TFT-LCD), digital light processing (DLP) display, liquid crystal on silicon (LCOS) display, or laser beam scanning (LBS).

[0071] In a possible implementation manner, the holographic optical element HOE provided in the embodiments of the present application can be as Figure 4 shown, arranged in a double-layer windshield (can also be pasted on the windshield), or can be included in the rear-stage optical system. For example, as part of a light diffusing element, by recording all the information of light through holographic exposure, combining the transmission / reflection function of the holographic optical element, specific optical design, excellent diffraction efficiency, light transmittance, etc., it is possible to project a 3D stereoscopic image in front of a person (such as a driver). Based on the high light transmittance of the holographic optical film material, the combination of virtual and real can be realized.

[0072] In some embodiments, the composition provided in the present application includes: a visible light photosensitizer, a co-initiator paired with the visible light photosensitizer, a matrix polymer, and at least one monomer; wherein, the general formula of the visible light photosensitizer is: Cn + An - ; Cn + represents a cation, selected from cyanine dyes, phenothiazine, benzothiophene, anthraquinone, phenoxazine, thioxanthone and other biological dyes; An - represents an anion, including one or a combination of an alkyl chain, a halogen, phosphorus, oxygen, nitrogen, sulfur, boron, a metal ion, etc.

[0073] In the above embodiments, a cation Cn of a biological dye such as cyanine, phenothiazine, benzothiophene, anthraquinone, phenoxazine, thioxanthone, etc. is used as a visible light photosensitizer + and a combination of one or more of an alkyl chain, halogen, phosphorus, oxygen, nitrogen, sulfur, etc. is used as an anion An of the visible light photosensitizer - Through such a combination between the cation Cn + and the anion An - the redox potential of the visible light photosensitizer is adjusted, making the visible light photosensitizer and the co-initiator paired with it in the composition more stable in the ground state. In this way, when the composition is subjected to processes such as high temperature / high pressure to form a holographic optical element, since the visible light photosensitizer and the co-initiator paired with it are more stable, the phenomenon of photosensitizer failure will not occur, so high photosensitivity is still maintained, and the monomer will not be induced to polymerize prematurely or other side reactions will not occur, thus avoiding the phenomenon of fogging and ensuring that a holographic grating with a high diffraction efficiency is obtained in subsequent exposure.

[0074] It should be noted that since the stability of the visible light photosensitizer is improved by adjusting its redox potential in the embodiments of the present application, its subsequent bleachability will not be affected.

[0075] In a possible implementation manner, the above metal ion can be a zinc ion or an iron ion.

[0076] In a possible implementation manner, the above matrix polymer can be polymethyl methacrylate (PMMA).

[0077] In a possible implementation manner, the refractive index of the above monomer at 405 nm is greater than 1.5.

[0078] In a possible implementation manner, the above monomer has the following chemical structure:

[0079]

[0080] wherein R1 is H or CH3; R2 is one or several of phenethyl, phenoxyethyl, o-phenylphenethoxy, 4-(1-methyl-1-phenylethyl)phenoxyethyl, 2,4,6-tribromophenyl, 2,4,6-tribromophenoxyethyl, pentabromophenyl, pentabromophenoxy, naphthyl, naphthoxy, 1,3-bis(thiophen-2-ylthio)propan-2-yl, 1,3-bis((4-(phenylthio)phenyl)thio)propan-2-yl, 1,3-bis((4-bromophenyl)thio)propan-2-yl.

[0081] In a possible implementation, the above monomer may be 9,9-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene (ABPEF).

[0082] In a possible implementation, the above visible light photosensitizer may be selected from substances with the following structural formulas:

[0083]

[0084]

[0085]

[0086] In some other embodiments, the visible light photosensitizer may also be selected from substances with the following structural formulas:

[0087]

[0088] In a possible implementation, the above co-initiator includes secondary or tertiary aliphatic or aromatic amines, alkyl aryl borate ammonium salts, alcohols or thiols, and reagents with hydrogen / donor electron donors, and can act with the visible light photosensitizer based on the Norrish II type of photoinitiation mechanism.

[0089] In a possible implementation, the above co-initiator may be selected from substances with the following structural formulas:

[0090]

[0091]

[0092]

[0093] The matrix polymer and monomer used in the above composition are only for illustrative purposes, and the embodiments of the present application are not limited thereto.

[0094] In a possible implementation, during the process of heating the above composition from room temperature (25 °C) to 200 °C, the thermogravimetric loss of the composition < 1.2 wt%. It can be seen that the composition provided by the embodiments of the present application exhibits high thermal stability during the high-temperature treatment process.

[0095] In a possible implementation, after heating the above composition at 120 °C for 30 min, the change value of T 640 is less than or equal to 40%, and T 640 of the composition is less than or equal to 80%; wherein, T 640It represents the light transmittance of visible light with a wavelength of 640 nm. It can be seen that for the composition provided in the embodiments of the present application, after high-temperature treatment, the change in the light transmittance of visible light with a wavelength of 640 nm is small, and the light transmittance of visible light with a wavelength of 640 nm can reach up to 80%, indicating that there is still good absorption of visible light with a wavelength of 640 nm, and it shows that the photosensitizer has not failed.

[0096] In a possible implementation manner, after heating the above composition at 120 °C for 30 min, the haze of the composition is less than or equal to 8%. It can be seen that for the composition provided in the embodiments of the present application, after high-temperature treatment, almost no atomization phenomenon occurs, indicating that almost no premature thermal polymerization of monomers occurs, and the composition has high thermal stability. Thus, when performing subsequent exposure treatment on it, a holographic grating with high diffraction efficiency can be exposed.

[0097] In a possible implementation manner, after heating the above composition at 120 °C for 30 min, the double-bond conversion rate of the composition is less than or equal to 20%. It can be seen that for the composition provided in the embodiments of the present application, after high-temperature treatment, it indicates that almost no premature thermal polymerization of monomers occurs, and the composition has high thermal stability. Thus, when performing subsequent exposure treatment on it, a holographic grating with high diffraction efficiency can be exposed.

[0098] In a possible implementation manner, in the ultraviolet-visible light spectrum of the above composition, the position λmax of the maximum absorption peak of the composition is located at 600 nm - 660 nm.

[0099] The embodiments of the present application also provide a preparation method of a composition, including the following steps:

[0100] Step 1: Prepare a solution, which includes a matrix polymer, a visible-light photosensitizer, and a monomer.

[0101] In a specific implementation, according to a predetermined ratio, polymethyl methacrylate (PMMA) can be used as the matrix polymer, which is dissolved in dichloromethane (DCM) solvent and fully dissolved for 1 h. Then, a methanol (MeOH) mother liquor of a visible-light photosensitizer (such as a red-light photosensitizer) is prepared, and the dissolution process is fully stirred for 1 h. Then, the monomer 9,9-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene (ABPEF) and the co-initiator N-methyldiethanolamine (MDEA) are successively added to the PMMA solution, and the mother liquor of the visible-light photosensitizer is added, and stirred at room temperature to obtain a solution.

[0102] Step 2: Use the solution obtained in Step 1 to prepare a HOE film.

[0103] In a specific implementation, a filter head with a size of 3 μm is used to filter the solution obtained in the above step 1, and a defoamer is used to defoam the filtered solution. Then, a square film former (with a specification of 75 μm) is used to coat the defoamed solution into a film, obtaining a HOE film. Next, the obtained HOE film is placed in an oven at 60 °C and baked for 20 min to remove the solvents of dichloromethane and methanol.

[0104] Optionally, a protective film can be attached to the obtained HOE film.

[0105] In some embodiments, the method for preparing the composition provided in the embodiments of the present application may further include:

[0106] Step 3: Perform exposure and bleaching treatments on the HOE film prepared in step 2.

[0107] In a specific implementation, the protective film on the HOE film prepared in step 2 is removed, the HOE film is attached to glass, and a laser with a predetermined wavelength is used to expose for a certain duration according to a preset power density. For example, a red laser with a wavelength of 640 nm is used to expose at a power density of 0.5 mW / cm 2 for 60 s. Then, the exposed sample is post-treated by heating at 60 °C for 5 min. The sample is bleached with white light LEDs for 1 h.

[0108] The above composition, the HOE film containing the composition, are introduced through specific examples below, and the performances of various HOE films are tested.

[0109] Example 1

[0110] In Example 1 of the present application, according to the above step 1, step 2, and the raw material ratios shown in Table 1, a HOE film sample 1 is prepared.

[0111] Table 1

[0112]

[0113] Perform performance tests on the HOE film sample 1 prepared in the above Example 1. Perform performance tests on the HOE film sample 1 prepared in the above Example 1. Use an ultraviolet-visible spectrophotometer to measure the transmittance of the HOE film sample 1 in the wavelength range of 400 nm - 800 nm, and then use the Figure 5 method shown to obtain the minimum transmittance (Tmin) of the reflection peak and the transmittance (T A ) of the baseline, and calculate the diffraction efficiency according to Equation (1).

[0114]

[0115] (1) Influence of high-temperature treatment on the visible light transmittance of the HOE film sample 1.

[0116] After heating the above HOE thin film sample 1 at 120 °C for 30 min, the transmittance of the HOE thin film sample 1 after high-temperature heating to red light was measured, and the test results are as Figure 6 shown. The test results show that for the HOE thin film sample 1 prepared by using BB3 as the photosensitizer and MDEA in combination, after high-temperature heating, its T 640 changed from 5.7% to 16.7%, with only a change of about 10%. The photoinitiating system after high-temperature heating still has a high absorbance to red light. At the same time, there is almost no change in the appearance and display color of the HOE thin film sample 1 before and after being heated at high temperature. Among them, T 640 represents the transmittance to visible light with a wavelength of 640 nm.

[0117] (2) Influence of high-temperature treatment on the exposure performance of HOE thin film sample 1.

[0118] After heating the above HOE thin film sample 1 at 120 °C for 30 min, the exposure performance of the HOE thin film sample 1 after high-temperature heating was measured. The test results show that the T 400 of the HOE thin film sample 1 without high-temperature treatment is 65%, the diffraction efficiency is 71%, T 可见光 is 81%, and the haze is 2.9. The T 400 of the HOE thin film sample 1 after high-temperature treatment is 68%, the diffraction efficiency is 73%, T 可见光 is 83%, and the haze is 2.3. It can be seen that the exposure performance of the HOE thin film sample 1 is not affected by high-temperature treatment. Among them, the test results of the transmittance of the HOE thin film sample 1 to visible light before and after high-temperature treatment are as Figure 7 shown.

[0119] Example 2

[0120] In Example 2 of the present application, according to the above-mentioned Step 1, Step 2 and the raw material ratios shown in Table 2, the HOE thin film sample 2 was prepared.

[0121] Table 2

[0122]

[0123] The performance of the HOE thin film sample 2 prepared in the above Example 2 was tested. The ultraviolet-visible spectrophotometer was used to measure the transmittance of the HOE thin film sample 2 in the wavelength range of 400 nm - 800 nm, and then the minimum transmittance (Tmin) of the reflection peak and the transmittance of the baseline (T Figure 5 ) were obtained by the method shown in A , and the diffraction efficiency was calculated according to Equation (1).

[0124] (1) Influence of high-temperature treatment on the visible light transmittance of HOE thin film sample 2.

[0125] Under the condition of 120 °C, after heating the above-mentioned HOE thin film sample 2 for 30 min, the transmittance of the HOE thin film sample 2 after high-temperature heating to red light was measured. The test results are as Figure 8 shown. The test results show that for HOE thin film sample 2 prepared by using pinacyanol iodide (1,1'-Diethyl-2,2'-Carbocyanine Iodide, DCI) as the photosensitizer and MDEA in combination, after high-temperature treatment, its T 640 changed from 12.6% to 20.0%, and there was only a 7.4% change in the light transmittance before and after heating. The photoinitiating system after high-temperature heating still had a high absorbance to red light. At the same time, there was almost no change in the appearance and display color of the HOE thin film sample 2 before and after being heated at high temperature. Among them, T 640 represents the transmittance of visible light with a wavelength of 640 nm.

[0126] (2) Influence of high-temperature treatment on the exposure performance of HOE thin film sample 2.

[0127] Under the condition of 120 °C, after heating the above-mentioned HOE thin film sample 1 for 30 min, the exposure performance of the HOE thin film sample 2 after high-temperature heating was measured. The test results show that the T 400 of the HOE thin film sample 2 without high-temperature treatment was 73%, the diffraction efficiency was 95%, the T 可见光 was 84%, and the haze was 0.8. The T 400 of the HOE thin film sample 2 after high-temperature treatment was 74%, the diffraction efficiency was 91%, the T 可见光 was 85%, and the haze was 1.2. It can be seen that the exposure performance of the HOE thin film sample 2 was affected by high-temperature treatment and decreased, but it could still expose the corresponding grating. Among them, the test results of the visible light transmittance of the HOE thin film sample 2 before and after high-temperature treatment are as Figure 9 shown.

[0128] Comparative Example 1

[0129] In Comparative Example 1 of this application, according to the above-mentioned Step 1, Step 2 and the raw material ratios shown in Table 3, HOE thin film sample 3 was prepared.

[0130] Table 3

[0131]

[0132] The performance of the HOE thin film sample 3 prepared in the above Comparative Example 1 was tested. The transmittance of the HOE thin film sample 3 in the wavelength range of 400 nm - 800 nm was measured by using an ultraviolet-visible spectrophotometer, and then by using Figure 5The method described above obtains the minimum transmittance (Tmin) of the reflection peak and the transmittance (T A ) of the baseline, and calculates the diffraction efficiency according to Equation (1).

[0133] (1) Influence of high-temperature treatment on the visible light transmittance of HOE thin film sample 3.

[0134] Under the condition of 120 °C, after heating the above-mentioned HOE thin film sample 3 for 30 min, the transmittance of the HOE thin film sample 3 after high-temperature heating to red light was measured, and the test results are as Figure 10 shown. The test results show that for the HOE thin film sample 3 prepared by using Newmethylene blue (NMB) as the photosensitizer and MDEA in combination, after high-temperature heating, its T 640 changed from 35.4% to 81.4%, with a 50% change in transmittance before and after heating. After high-temperature heating, the absorption peak of the HOE thin film sample 3 in red light showed a significant attenuation. At the same time, the appearance of the HOE thin film sample 3 after being subjected to high-temperature treatment showed that the color of the HOE thin film sample 3 became colorless, indicating that the NMB photosensitive system completely failed after high-temperature heating.

[0135] (2) Influence of high-temperature treatment on the exposure performance of HOE thin film sample 3.

[0136] Under the condition of 120 °C, after heating the above-mentioned HOE thin film sample 1 for 30 min, the exposure performance of the HOE thin film sample 3 after high-temperature heating was measured. The test results show that the T 400 of the HOE thin film sample 3 without high-temperature treatment was 48.8%, the diffraction efficiency was 84.7%, the T 可见光 was 80.5%, and the haze was 8.4. The T 400 of the HOE thin film sample 3 after high-temperature treatment was 66.2%, the diffraction efficiency was 2.6%, the T 可见光 was 86.7%, and the haze was 2.5. It can be seen that the exposure performance of the HOE thin film sample 3 is affected by high-temperature treatment, and it is almost impossible to expose a grating, and the diffraction efficiency for red light almost disappears. Among them, the test results of the visible light transmittance of the HOE thin film sample 3 before and after high-temperature treatment are as Figure 11 shown.

[0137] Based on the composition provided in the above embodiments and the preparation method of the composition, the embodiments of the present application further provide a holographic optical element, including an optical film layer, a functional film layer, and a protective layer stacked in sequence; the functional film layer includes the composition provided in any of the above embodiments. In these embodiments, the holographic optical element includes a thin film lens that has not been exposed and bleached.

[0138] Based on the composition and the preparation method of the composition provided in the above embodiments, an embodiment of the present application further provides a holographic optical element, including an optical film layer, a functional film layer, and a protective layer stacked in sequence; the functional film layer is obtained by exposing a raw material film layer, and the raw material film layer includes the composition provided in any of the above embodiments. In these embodiments, the holographic optical element includes a thin film lens that has been exposed and bleached.

[0139] Based on the composition and the preparation method of the composition provided in the above embodiments, an embodiment of the present application further provides a projection device, which includes an image generation unit and an optical imaging module. The optical imaging module includes the holographic optical element provided in the above embodiments; the image generation unit is configured to generate an imaging light beam based on image information and emit the imaging light beam, and the holographic optical element is located on the propagation path of the imaging light beam. Exemplarily, the projection device can be, for example, Figure 3 and Figure 4 the head-up display device shown. The optical imaging module included in the projection device can include, for example, Figure 3 and Figure 4 the rear-stage optical system in the head-up display device shown.

[0140] Based on the composition and the preparation method of the composition provided in the above embodiments, an embodiment of the present application further provides a display device, which includes a processor and the projection device provided in the above embodiments. The processor is configured to send image information to the image generation unit. Exemplarily, the display device can be a VR glasses, a vehicle head-up display device. The display device can also be a projection display device used in occasions such as home, classroom, meeting room, auditorium, cinema, stadium, square, etc., or a network TV, a smart TV, an Internet Protocol TV (IPTV), or integrated therein.

[0141] Based on the composition and the preparation method of the composition provided in the above embodiments, an embodiment of the present application further provides a vehicle, which includes a display device, a reflection element, and the holographic optical element provided in the above embodiments; the display device is installed on the vehicle; the display device includes a processor and a projection device; the projection device includes an image generation unit and an optical imaging module; the processor is configured to send image information to the image generation unit, the image generation unit is configured to generate an imaging light beam based on image information, and the optical imaging module is configured to project the imaging light beam; the reflection element and the holographic optical element are located on the propagation path of the imaging light beam.

[0142] The reflection element included in the vehicle may specifically be its front windshield (i.e., the front windscreen). Exemplarily, the vehicle may be a sedan, a truck, a motorcycle, a bus, a ship, an airplane, a helicopter, a lawn mower, a recreational vehicle, a fairground vehicle, construction equipment, a tram, a golf cart, a train, and a trolley, etc., and the embodiments of the present application are not particularly limited thereto.

[0143] On the vehicle, the content of the image displayed by the display device includes but is not limited to map auxiliary information, indication information of external objects, status information of the vehicle, and entertainment information, etc. The map auxiliary information is used for assisting driving. For example, the map auxiliary information includes but is not limited to direction arrows, distances, and travel times, etc. The indication information of external objects includes but is not limited to safe driving distances, surrounding obstacles, and reverse images, etc. Taking an automobile as an example, the status information of the vehicle is generally the information displayed on the vehicle instrument, which is also called instrument information, and includes but is not limited to information such as driving speed, driving mileage, fuel quantity, water temperature, and headlight status.

[0144] The above-described embodiments of the present invention do not constitute a limitation on the protection scope of the present invention.

Claims

1. A composition, characterized in that, Comprising: A visible light photosensitizer, a co-initiator, a matrix polymer, and at least one monomer; wherein, the general formula of the visible light photosensitizer is: Cn + An - ; Cn + represents a cation, and Cn + includes one or more structures selected from cyanine, phenothiazine, benzothiophene, anthraquinone, phenoxazine, thioxanthone; An - represents an anion, and Cn + includes one or more of linear alkyl, halogen, phosphorus, oxygen, nitrogen, sulfur, boron, metal ions.

2. The composition according to claim 1, wherein The co-initiator includes secondary or tertiary aliphatic or aromatic amines, alkyl aryl ammonium borates, alcohols or thiol reagents, and the co-initiator has a hydrogen donor or an electron donor.

3. The composition according to claim 1, characterized in that, The visible light photosensitizer is selected from substances with the following structural formulas:

4. The composition according to claim 1, wherein The co-initiator is selected from substances with the following structural formulas:

5. The composition according to claim 1, wherein During the process of heating the composition from room temperature to 200 °C, the thermal weight loss of the composition < 1.2 wt%.

6. The composition according to claim 1, wherein After the composition is heated at 120 °C for 30 min, the change value of T of the composition is less than or equal to 40%, and T of the composition is less than or equal to 80%; wherein, T represents the light transmittance of visible light with a wavelength of 640 nm. 640 640 640 ​ 7. The composition according to claim 1, characterized in that, After the composition is heated at 120 °C for 30 min, the haze of the composition is less than or equal to 8%.

8. The composition according to claim 1, wherein After the composition is heated at 120 °C for 30 min, the double bond conversion rate of the composition is less than or equal to 20%.

9. The composition according to claim 1, wherein In the ultraviolet-visible light spectrum of the composition, the position of the maximum absorption peak λmax of the composition is located at 600 nm - 660 nm.

10. A holographic optical element, characterized in that, Comprising: An optical film layer, a functional film layer, and a protective layer stacked in sequence; the functional film layer includes the composition according to any one of claims 1-9.

11. A holographic optical element, characterized in that, Comprising: An optical film layer, a functional film layer, and a protective layer stacked in sequence; The functional film layer is obtained by exposing a raw material film layer, and the raw material film layer includes the composition according to any one of claims 1-9.

12. A projection device, characterized in that, Comprising an image generation unit and an optical imaging module, the optical imaging module includes the holographic optical element according to claim 11; the image generation unit is used to generate an imaging light beam based on image information and emit the imaging light beam, and the holographic optical element is located on the propagation path of the imaging light beam.

13. A display device, characterized in that, Comprising a processor and the projection device according to claim 12, and the processor is used to send the image information to the image generation unit.

14. A vehicle, characterized in that, Comprising a display device, a reflection element, and the holographic optical element according to claim 11; the display device is installed on the vehicle; the display device includes a processor and a projection device; the projection device includes an image generation unit and an optical imaging module; The processor is used to send image information to the image generation unit, the image generation unit is used to generate an imaging light beam based on the image information, and the optical imaging module is used to project the imaging light beam; the reflection element and the holographic optical element are located on the propagation path of the imaging light beam.

15. The vehicle according to claim 14, wherein, The reflection element includes the front windshield of the vehicle.

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