Polymer composition, polymer film, holographic grating and manufacturing method therefor, optical film, and display device

Abstract

The present application provides a polymer composition, a polymer film, a holographic grating and a manufacturing method therefor, an optical film, and a display device. The polymer composition of the present application comprises a first polymerizable monomer, a second polymerizable monomer, and a film-forming resin. The first polymerizable monomer is a non-liquid crystal monomer; and the second polymerizable monomer is a liquid crystal monomer, the second polymerizable monomer comprises an active group, and the second polymerizable monomer may undergo a copolymerization reaction with the first polymerizable monomer by means of the active group under illumination. By using the polymer composition, the refractive index modulation degree of an optical film material can be improved.

Description

Polymer composition, polymer film material, holographic grating and preparation method thereof, optical film material and display device

[0001] Cross-reference to related applications

[0002] This application claims priority to the Chinese patent application No. 202410898555.6, filed on July 4, 2024, entitled “Polymer composition, polymer film material, holographic grating and preparation method thereof, optical film material and display device”, the entire content of which is incorporated herein by reference. TECHNICAL FIELD

[0003] The present application relates to the field of display materials, in particular to a polymer composition, a polymer film material, a holographic grating and a preparation method thereof, an optical film material and a display device. BACKGROUND

[0004] Holographic polymer material is a material for recording the intensity and amplitude of light waves of an object, which is usually exposed by coherent laser. When the three-dimensional object information is modulated in the coherent light, it can be reproduced by the reference light. In particular, if the coherent light modulates lens information, it can be used as a plane optical lens for vehicle head-up display (HUD); if the holographic polymer material modulates a special structure of grating, it can be used for beam expansion, turning and other special functions of AR eyes.

[0005] Holographic polymer material is generally composed of film-forming resin, polymerizable monomer and photoinitiator. Because the refractive index of the film-forming resin is different from that of the monomer, a grating with periodic distribution of refractive index is formed during the recording of coherent light by the holographic polymer material. The refractive index modulation degree is an important optical parameter of the holographic polymer material, which determines the product performance such as the field of view (FOV) light efficiency of HUD, augmented reality (AR) glasses and other application fields. There are generally two factors that determine the refractive index modulation degree: the first is the refractive index difference between the polymerizable monomer and the film-forming resin, the greater the refractive index difference between the two, the greater the refractive index modulation degree; the second is the diffusion ability of the polymerizable monomer and the phase separation ability with the film-forming resin. However, increasing the refractive index of the polymerizable monomer will reduce its diffusion and phase separation ability. Therefore, the above two factors affecting the refractive index modulation degree are mutually restrictive, and it is impossible to increase the refractive index of the polymerizable monomer while improving its diffusion ability and phase separation ability. SUMMARY

[0006] The application provides a polymer composition, a polymer film material, a holographic grating and a preparation method thereof, an optical film material and a display device, so as to improve the phase separation ability of polymerizable monomers and film-forming resins and the refractive index modulation degree of optical film materials.

[0007] In a first aspect, the application provides a polymer composition, which comprises a first polymerizable monomer, a second polymerizable monomer and a film-forming resin. The first polymerizable monomer is a non-liquid crystal monomer; the second polymerizable monomer is a liquid crystal monomer, and the second polymerizable monomer comprises an active group and an aromatic group, and the second polymerizable monomer can undergo a copolymerization reaction with the first polymerizable monomer through the active group under light irradiation.

[0008] The polymer composition of the application can form bright and dark stripes after coherent light irradiation, and the first polymerizable monomer and the second polymerizable monomer can rapidly undergo a photoreaction in the bright stripe area to form a polymer. Since the second polymerizable monomer is a liquid crystal monomer, the second polymerizable monomer outside the bright stripe area can rapidly move to the bright stripe area under the action of the liquid crystal self-aggregation effect to continue the polymerization reaction. Since the second polymerizable monomer and the first polymerizable monomer can undergo a polymerization reaction to form a copolymer, and the second polymerizable monomer contains an aromatic group, and the film-forming resin does not undergo a chemical reaction with them, the film-forming resin has poor compatibility with the copolymer containing the aromatic group and is expelled to the dark stripe area. Therefore, the first polymerizable monomer can be driven to move in the direction of the bright stripe and undergo a polymerization reaction under the driving of the self-aggregation movement effect of the second polymerizable monomer, so as to improve the movement ability of the first polymerizable monomer and the phase separation ability between the first polymerizable monomer and the film-forming resin. Thus, even if the first polymerizable monomer adopts a monomer with a high refractive index, the separation of the first polymerizable monomer and the film-forming resin can be well realized under the action of the second polymerizable monomer in a liquid crystal phase. The optical film material prepared from the polymer composition of the application can have a better refractive index modulation degree.

[0009] In the polymer composition of the application, the order parameter S of the first polymerizable monomer is less than 0.3, and the first polymerizable monomer is in a non-liquid crystal phase; the order parameter S of the second polymerizable monomer is 0.3-1, and the second polymerizable monomer is in a liquid crystal phase. The order parameter S is represented as:

[0010] wherein θ is the included angle between the long axis of a molecule and the average orientation of the long axis of the molecules, and <(3cos 2 θ-1)> is the average value of 3cos 2 θ-1.

[0011] In an alternative implementation, the first polymerizable monomer has a refractive index of 1.5-1.8, the second polymerizable monomer has a refractive index of 1.5-1.8, and the film-forming resin has a refractive index of 1.3-1.5. The first polymerizable monomer and the second polymerizable monomer are high-refractive-index substances, and the film-forming resin is a low-refractive-index substance. During coherent light irradiation, the high-refractive-index first polymerizable monomer and the second polymerizable monomer are driven by the self-aggregation effect of the second polymerizable monomer to move to the bright stripe region, so that the first polymerizable monomer can have both high refractive index and high phase separation capability, and an optical film material with higher refractive index modulation can be obtained.

[0012] In an alternative implementation, the active group of the second polymerizable monomer includes at least one of an acrylate group, a methacrylate group, an allyl group, a mercapto group, a hydroxyl group, a phenolic hydroxyl group, a carboxyl group, an alkyne group, an epoxy group, an oxetanyl group, a vinyl group, an amine group, and an acrylamide group. Using a substance containing the above active group as the second polymerizable monomer can improve the consistency between the second polymerizable monomer and the first polymerizable monomer, and increase the polymerization degree between the two, so as to facilitate the control of the diffraction rate of the bright stripe region.

[0013] In an alternative implementation, the second polymerizable monomer further includes a non-active group, and the non-active group includes at least one of a linear group with 1-20 carbon atoms, a branched group with 1-20 carbon atoms, and an aromatic group with 1-20 carbon atoms. In addition to the active group, the second polymerizable monomer also needs to include a certain non-active group. The non-active group is used as the main structure of the second polymerizable monomer to form a polymer with a desired molecular weight. To improve the stability of the formed polymer, the non-active group in the second polymerizable monomer includes at least an aromatic group with 1-20 carbon atoms, such as benzene, biphenyl, naphthalene, etc. The linear group with 1-20 carbon atoms and the branched group with 1-20 carbon atoms can be selected from pure carbon chains, ether carbon chains, thioether carbon chains, fluorine-containing element carbon chains, etc., and the above carbon chains can be linear structures or branched structures.

[0014] It can be understood that the first polymerizable monomer also includes an active group, and the active group in the first polymerizable monomer can also be selected from at least one of an acrylate group, a methacrylate group, an allyl group, a mercapto group, a hydroxyl group, a phenolic hydroxyl group, a carboxyl group, an alkyne group, an epoxy group, an oxetanyl group, a vinyl group, an amine group, and an acrylamide group. The first polymerizable monomer containing the above active group can achieve better polymerization under light irradiation. The active group in the first polymerizable monomer can be the same as or different from that in the second polymerizable monomer. No specific limitation is made herein.

[0015] In an alternative implementation, the first polymerizable monomer has one active group and the second polymerizable monomer has one active group. Thus, the polymer formed by the copolymerization of the first polymerizable monomer and the second polymerizable monomer is a linear polymer. Since the film-forming resin is usually a cross-linked resin, it is more advantageous for the polymer to separate from the film-forming resin under light.

[0016] In an alternative implementation, the film-forming resin does not contain aromatic groups. In addition, the film-forming resin does not have liquid crystal properties. Thus, it is more advantageous for the film-forming resin to separate from the first polymerizable monomer and the second polymerizable monomer.

[0017] In an alternative implementation, the first polymerizable monomer also contains aromatic groups to work together with the second polymerizable monomer to increase the separation ability of the polymer from the film-forming resin.

[0018] In an alternative implementation, the aromatic groups in the first polymerizable monomer and the second polymerizable monomer can be aromatic groups with 5-20 carbon atoms, such as at least one of phenyl, biphenyl, naphthyl, anthryl, phenanthryl, carbazolyl, benzoic acid group, hydroxybenzoic acid group, phenol group, benzoquinone group, furan group, thiophene group, pyrrole group, thiazole group, pyrazole group, imidazole group, pyridine group, pyryl group, pyridine group, pyrazine group, quinoline group, isoquinoline group, indole group, thiazine group, purine group, and pteridine group.

[0019] In addition, the number of aromatic groups in the first polymerizable monomer and the second polymerizable monomer can be 1-15, for example, 1-10, for example, 1-5, and the like. Too many aromatic groups can affect the quality of the monomer and reduce the mobility of the monomer. Therefore, the number of aromatic groups is selected from the above range to ensure the mobility of the monomer while improving the separation ability of the polymer from the film-forming resin.

[0020] In an alternative implementation, the mass ratio of the first polymerizable monomer to the second polymerizable monomer is 100:1-1:100. In an alternative implementation, the mass ratio of the second polymerizable monomer to the film-forming resin is 1:100-100:10. In an alternative implementation, the mass ratio of the film-forming resin to the total mass of the first polymerizable monomer and the second polymerizable monomer is 100:5-10:100. By limiting the amount of the second polymerizable monomer added, the separation ability of the first polymerizable monomer can be improved without affecting the performance of the optical film material.

[0021] In an alternative implementation, the polymer composition further comprises a photoinitiator and a solvent. The first polymerizable monomer, the second polymerizable monomer, the photoinitiator, etc. are dispersed in the solvent to form a mixed liquid, which can be conveniently coated to form a film material. In addition, the polymer composition can further comprise other additives according to specific use occasions, such as flame retardants, etc., as long as the optical performance of the final optical film material is not affected.

[0022] In a second aspect, the application provides a polymer film material, which comprises the polymer composition of the application. In the preparation of the film material, the polymer composition in the form of a mixed liquid can be coated on the surface of a substrate, and after drying, a polymer film material can be formed.

[0023] In a third aspect, the application provides a holographic grating, which is obtained by illuminating the above-mentioned polymer film material after drying.

[0024] The holographic grating of the application is prepared using the polymer film material of the application. After illumination, the bright fringe region is mainly formed by the copolymerization of the first polymerizable monomer and the second polymerizable monomer, and the dark fringe region is mainly formed by the film-forming resin.

[0025] The holographic grating of the application has a thickness of 0.1 μm to 1500 μm, a diffraction efficiency of greater than 70%, a refractive index modulation of 0.03 to 0.05, and a haze of less than 1.0.

[0026] In a fourth aspect, the application further provides a holographic grating, which comprises a plurality of bright fringes and a plurality of dark fringes, the plurality of bright fringes and the plurality of dark fringes being arranged alternately, the bright fringes comprising a linear polymer having aromatic groups on the molecular side chains, the dark fringes comprising a film-forming resin, and the holographic grating having a refractive index modulation of greater than 0.01.

[0027] The holographic grating of the application has different resin materials corresponding to the bright fringes and the dark fringes, the material in the bright fringe region is a linear polymer, the material corresponding to the dark fringe region is a film-forming resin having crosslinking characteristics, and the refractive index difference between the two is higher, so that the refractive index modulation of the holographic grating is higher than 0.01.

[0028] In an implementation, the film-forming resin does not contain aromatic groups. The film-forming resin is a crosslinking resin. Alternatively, the number of aromatic groups on the molecular side chains in each repeating unit of the linear polymer is 1 to 15, for example, 1 to 10, for example, 1 to 5, etc. The number of aromatic groups is selected within the above range to achieve effective separation of the linear polymer and the film-forming resin.

[0029] In an implementation, the aromatic group of the molecular side chain of the linear polymer includes at least one of phenyl, biphenyl, naphthyl, anthryl, phenanthryl, carbazolyl, benzoic acid group, hydroxybenzoic acid group, phenol group, benzoquinone group, furan group, thiophene group, pyrrole group, thiazole group, pyrazole group, imidazole group, pyridine group, pyryl group, pyridine group, pyrazine group, quinoline group, isoquinoline group, indole group, thiazine group, purine group, and pteridine group. The aromatic group is selected to facilitate separation from the film-forming resin.

[0030] In an implementation, the holographic grating has a thickness of 0.1 μm to 1500 μm, a diffraction efficiency greater than 70%, a refractive index modulation of 0.03 to 0.05, and a haze less than 1.0.

[0031] In a fifth aspect, the present application provides a method for preparing a holographic grating, the method comprising:

[0032] performing film-forming treatment on a polymer composition to obtain a polymer film; wherein the polymer composition comprises a first polymerizable monomer, a second polymerizable monomer, and a film-forming resin; the first polymerizable monomer is a non-liquid crystal monomer; the second polymerizable monomer is a liquid crystal monomer, and the second polymerizable monomer comprises an active group and an aromatic group;

[0033] performing coherent light irradiation treatment on the polymer film, and the second polymerizable monomer in the polymer film undergoes a copolymerization reaction with the first polymerizable monomer through the active group after light irradiation to form the holographic grating.

[0034] In a sixth aspect, the present application provides an optical film, which comprises a base film and the holographic grating of the present application disposed on the surface of the base film.

[0035] In a seventh aspect, the present application provides a display device, which comprises the optical film of the present application.

[0036] In the above-mentioned possible implementation manners of the present application, the data such as the mass ratio of each component, the diffraction efficiency of the holographic grating, and the haze should be understood as being within the range defined by the present application within the range of the engineering measurement error. BRIEF DESCRIPTION OF DRAWINGS

[0037] FIG. 1 is a light transmittance comparison test diagram of the optical film of Example 1 and Comparative Example 1;

[0038] FIG. 2 is a light transmittance comparison test diagram of the optical film of Example 2 and Comparative Example 2;

[0039] FIG. 3 is a light transmittance comparison test diagram of the optical film of Example 3 and Comparative Example 3;

[0040] Figure 4 is a graph of the light transmittance comparison test of the optical film material of Example 4 and Comparative Example 4;

[0041] Figure 5 is a schematic diagram of the structure of an AR glass of an embodiment;

[0042] Figure 6 is a schematic diagram of the structure of a vehicle-mounted head-up display device of an embodiment. DETAILED DESCRIPTION

[0043] In order to make the purposes, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings.

[0044] The terms used in the following examples are only for the purpose of describing specific embodiments and are not intended to be limiting of the present application. As used in the specification and the appended claims, the singular forms "a," "an" and "the" are intended to include both singular and plural forms, unless the context clearly indicates otherwise.

[0045] Reference in the specification to "one embodiment" or "some embodiments" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the application. The appearances of the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," and the like in the specification do not necessarily all refer to the same embodiment, but signify that the feature, structure, or characteristic so mentioned is included in at least one embodiment of the application. The terms "including," "comprising," "having," and the like are meant to be inclusive and mean that there can be additional

[0046] For the convenience of understanding, the following terms are explained first.

[0047] Refractive index modulation: The size of refractive index modulation is an important parameter to measure the quality of a holographic polymer material and the corresponding processing technology. The higher the refractive index modulation, the higher the optical performance of the holographic polymer material.

[0048] Diffractive efficiency: When the incident angle of the probe light satisfies the Bragg condition, the intensity of the diffracted light of the holographic grating reaches the maximum, and the incident angle at this time is recorded as the Bragg angle. At this time, the ratio of the intensity of the diffracted light to the sum of the intensities of the diffracted light and the transmitted light is the diffraction efficiency of the grating. For a holographic grating, the diffraction efficiency refers to the ratio of the intensity in a certain diffraction direction to the incident light intensity. For a holographic grating element used in practical applications, the main consideration is that the light not only needs to change its propagation path when passing through the holographic grating element, but also needs to have sufficient intensity to be applied, that is, the diffraction efficiency of the holographic grating element occupies an important position.

[0049] Coherent laser: laser with the same frequency, the same vibration direction, the same phase or the constant phase difference. When coherent lasers overlap with each other, a stable phase difference can be generated, and the combined amplitude is also constant, which can form a stable light intensity distribution and form interference fringes.

[0050] Haze: refers to the percentage of the intensity of transmitted light deviating from the incident light by more than 2.5° in the total transmitted light intensity. The greater the haze, the lower the film gloss and transparency, and the lower the imaging degree.

[0051] Holography refers to a technology for 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 diverse, and holographic photopolymers are widely used in high-end anti-counterfeiting, holographic data storage, holographic optical element manufacturing, and high-tech fields such as augmented reality (AR) and head-up display (HUD) due to their advantages of flexible processing, wide photosensitive range, and high diffraction efficiency. Holographic optical elements (HOE) based on holographic photopolymers have high light transmittance, high light utilization efficiency, good wavelength selectivity, easy processing, light weight, and can achieve high-degree optical function design, which helps to enhance the flexibility of augmented reality (AR) display systems. In the process of forming a grating, the movement speed of the polymerizable monomer and the phase separation ability with the film-forming resin have an important influence on the refractive index modulation degree of the holographic grating element obtained finally. Although increasing the refractive index of the polymerizable monomer can increase the refractive index modulation degree of the holographic grating element, it will reduce the diffusion ability and phase separation ability of the polymerizable monomer, which is not conducive to the formation of a grating structure with high and low refractive index distribution. A current method is to increase the thermal annealing treatment to improve the diffusion of the polymerizable monomer, but this method will increase the processing time of the grating and also damage the structure of the grating, reducing the optical performance.

[0052] Therefore, the present application provides a kind of polymer composition. The polymer composition includes film-forming resin, and first polymerizable monomer in non-liquid crystal phase and second polymerizable monomer in liquid crystal phase. After being irradiated by coherent light, the second polymerizable monomer has self-aggregation effect, so that the second polymerizable monomer can drive the first polymerizable monomer to move to the bright fringe area of coherent light during diffusion, while extruding the film-forming resin to the dark fringe area of coherent light, thereby realizing efficient diffusion of the first polymerizable monomer and efficient separation with the film-forming resin.

[0053] The film-forming resin in the polymer composition of the embodiments of the present application is a polymer with a molecular weight greater than 1000 and is not reactive. The film-forming resin is a cross-linked polymer that does not contain aromatic groups in its molecular structure. The film-forming resin can be selected from substances with a refractive index of 1.3 to 1.5, such as polyacrylate, polyvinyl acetate, polystyrene, cellulose acetate, polyethylene, and the like.

[0054] The first polymerizable monomer is a non-liquid crystal monomer with an order parameter S less than 0.3 and in a non-liquid crystal phase. The order parameter S can be expressed as:

[0055] where θ is the angle between the long axis of the molecule and the average orientation of the long axis of the molecule, and <3cos 2 θ-1> is the average value of 3cos 2 θ-1.

[0056] The first polymerizable monomer satisfying the above order parameter can be considered as a non-liquid crystal monomer.

[0057] In the embodiments of the present application, the first polymerizable monomer contains active groups to undergo polymerization under the irradiation of coherent light to form a polymer. The first polymerizable monomer can include at least one monomer with only one active group. Exemplarily, the active group in the first polymerizable monomer can be selected from at least one of acrylate, methacrylate, allyl, thiol, hydroxyl, phenolic hydroxyl, carboxyl, alkyne, epoxy, oxetane, vinyl, amine, and acrylamide groups. In addition to the active group, the first polymerizable monomer can also include a non-active group to provide a main structure for the first polymerizable monomer for forming a polymer. The non-active group in the first polymerizable monomer can contain an aromatic group. The non-active group can be separated from the film-forming resin during polymerization.

[0058] The first polymerizable monomer can be selected from substances with a refractive index of 1.5 to 1.8 to increase the refractive index modulation of the holographic optical element. Exemplarily, the first polymerizable monomer can be selected from monomer substances such as methyl methacrylate, 2-([1,1'-biphenyl]-2-oxyl)ethyl 2-acrylate, 4-biphenylmethanol acrylate, 2-N-morpholinoethyl methacrylate, and the like, in addition to other conventional polymerizable monomers in holographic optical elements.

[0059] The second polymerizable monomer is a liquid crystal monomer with a sequence parameter S of 0.3 to 1, and is in a liquid crystal phase. The second polymerizable monomer also contains active groups, and contains aromatic groups. After being irradiated by coherent light, the second polymerizable monomer can copolymerize with the first polymerizable monomer through the active groups, and can also self-polymerize through the active groups. In addition, the first polymerizable monomer can also copolymerize with the second polymerizable monomer through the active groups after being irradiated by coherent light, and can also self-polymerize through the active groups. After being irradiated by coherent light, the first polymerizable monomer and the second polymerizable monomer can form a polymer to form a high molecular material with a certain structural strength. The aromatic groups in the second polymerizable monomer can promote separation from the film-forming resin.

[0060] The second polymerizable monomer includes at least one monomer with one active group. When the active groups in the first polymerizable monomer and the second polymerizable monomer are both one, the two can form a linear polymer after polymerization to improve the separation ability from the film-forming resin. Of course, in addition to the monomer with one active group, other monomers with more than one active group can also be selected as the first polymerizable monomer or the second polymerizable monomer.

[0061] The active groups in the second polymerizable monomer can be selected from at least one of an acrylate group, a methacrylate group, an allyl group, a mercapto group, a hydroxyl group, a phenolic hydroxyl group, a carboxyl group, an alkyne group, an epoxy group, an oxetane group, a vinyl group, an amine group, and an acrylamide group. The active groups in the second polymerizable monomer and the first polymerizable monomer can be the same or different. In addition to the active groups, the second polymerizable monomer can also include non-active groups to form a high molecular polymer through the main structure. The second polymerizable monomer can be selected from a substance with a refractive index of 1.5 to 1.8, and the refractive index of the second polymerizable monomer can be the same or similar to that of the first polymerizable monomer. At the same time, the refractive indices of the first polymerizable monomer and the second polymerizable monomer should be different from that of the film-forming resin to obtain a grating with different refractive indices in bright and dark areas.

[0062] The non-active groups in the second polymerizable monomer can be selected from at least one of a linear group with 1 to 20 carbon atoms, a branched group with 1 to 20 carbon atoms, and an aromatic group with 1 to 20 carbon atoms. The linear group with 1 to 20 carbon atoms and the branched group with 1 to 20 carbon atoms can be selected from pure carbon chains, ether carbon chains, thioether carbon chains, fluorine-containing carbon chains, etc., which can be linear or branched. The aromatic group with 1 to 20 carbon atoms can be a group such as benzene, biphenyl, naphthalene, etc. In order to improve the stability of the formed polymer, the non-active groups in the second polymerizable monomer include at least an aromatic group with 1 to 20 carbon atoms.

[0063] As an illustrative example, the non-reactive group in the second polymerizable monomer can be selected from the following structural groups:

[0064] As an illustrative example, the second polymerizable monomer in the embodiments of the present application can be selected from at least one of the following compounds:

[0065] In one embodiment, the mass ratio of the first polymerizable monomer to the second polymerizable monomer is 100:1-1:100, such as 100:5-10:100, further such as 100:10-50:100, and further such as 100:20-60:100. In addition, the mass ratio of the second polymerizable monomer to the film-forming resin can be 1:100-100:10. In an alternative implementation, the mass ratio of the film-forming resin to the total mass of the first polymerizable monomer and the second polymerizable monomer can be 100:5-10:100, such as 100:10-20:100, and further such as 100:30-40:100.

[0066] It can be understood that the polymer composition of the embodiments of the present application can include, in addition to the first polymerizable monomer, the second polymerizable monomer, and the film-forming resin, a photoinitiator and a solvent. The first polymerizable monomer, the second polymerizable monomer, the photoinitiator, and the like are dispersed in the solvent to form a mixed liquid to facilitate coating to make a film material. The photoinitiator can be selected from at least one of cyanine, coumarin, diphenylpyrazine, phenothiazine, phenoxazine, pyrrole boron, and triarylmethane compounds. The solvent can be selected from one or a combination of at least two of methanol, ethanol, n-butanol, isopropanol, N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran, and cyclohexanone.

[0067] In addition, the polymer composition can further include other additives such as flame retardants and the like according to specific use occasions, as long as the optical performance of the final optical film material is not affected.

[0068] Based on the same technical purpose, the embodiments of the present application further provide a polymer film material. The polymer film material includes the polymer composition of the present application.

[0069] The polymer film material of the embodiments of the present application can be made of the polymer composition of the embodiments of the present application. In making the polymer film material, the polymer composition in the form of a mixed liquid containing the first polymerizable monomer, the second polymerizable monomer, the film-forming resin, the solvent, and the photoinitiator can be coated on the surface of a substrate, and after drying, the polymer film material can be formed. After drying, the solvent can be removed, and the first polymerizable monomer, the second polymerizable monomer, the film-forming resin, and the photoinitiator and the like remain in the formed polymer film material.

[0070] Based on the same technical purpose, the embodiment of the present application also provides a holographic grating. The above high molecular film material is subjected to light treatment to obtain the holographic grating. The light treatment is coherent laser irradiation treatment. During the light treatment, the first polymerizable monomer and the second polymerizable monomer in the high molecular film material move to the bright fringe area and polymerize to form a polymer. The film-forming resin in the high molecular film material is extruded to the dark fringe area, thereby forming a grating with a refractive index high-low distribution.

[0071] Based on the similar technical purpose, the embodiment of the present application also provides a holographic grating. The holographic grating includes a plurality of bright fringes and a plurality of dark fringes. The plurality of bright fringes and the plurality of dark fringes are arranged alternately,

[0072] The material of the bright fringe area is mainly a linear polymer. The molecular side chain of the linear polymer is provided with an aromatic group. The number of aromatic groups of the molecular side chain in each repeating unit of the linear polymer is 1-15. Exemplarily, the aromatic group may, for example, be selected from at least one of a phenyl group, a biphenyl group, a naphthyl group, an anthryl group, a phenanthryl group, a carbazyl group, a benzoic acid group, a hydroxybenzoic acid group, a phenol group, a benzoquinone group, a furan group, a thiophene group, a pyrrole group, a thiazole group, a pyrazole group, an imidazole group, a pyridine group, a pyryl group, a pyridine group, a pyrazine group, a quinoline group, an isoquinoline group, an indole group, a thiazine group, a purine group, and a pteridine group.

[0073] The material of the dark fringe area is mainly a film-forming resin. The film-forming resin is a cross-linked polymer and has a network structure. Moreover, the film-forming resin does not contain an aromatic group. As described above, due to the difference in material between the bright fringe area and the dark fringe area, the compatibility of the two is poor, and the separation degree is higher, thereby making the refractive index modulation degree of the holographic grating greater than 0.01.

[0074] Based on the similar technical purpose, the embodiment of the present application also provides an optical film material. The optical film material includes a base film and the holographic grating of the embodiment of the present application arranged on the surface of the base film. The base film in the optical film material is a transparent film and plays a supporting and protecting role for the holographic grating. The base film may, for example, be a polyethylene terephthalate film, a cellulose triacetate film, a polymethyl methacrylate film, or a polycarbonate film.

[0075] In an embodiment, the thickness of the optical film material of the embodiment of the present application is 0.1 μm-1500 μm, such as 0.1 μm-1000 μm, for example, 1 μm-500 μm, for example, 1 μm-100 μm. The haze thereof may be less than 1.0, such as less than 0.95, for example, less than 0.9.

[0076] In addition, it has been tested that the diffraction efficiency of the optical film material of the embodiment of the present application is greater than 70%, and the refractive index modulation degree is 0.03-0.05.

[0077] The performance of the optical film material of the present application will be further described below in connection with specific examples and comparative examples.

[0078] Example 1

[0079] An optical film material is formed using a polymer composition. The polymer composition comprises 34% of non-liquid crystal monomers, 15% of liquid crystal monomers, 50% of film-forming resin, and 1% of photoinitiator, with an appropriate amount of solvent. The content of the non-liquid crystal monomers, the content of the liquid crystal monomers, the content of the film-forming resin, and the content of the photoinitiator are all measured based on the total weight after removing the solvent.

[0080] The non-liquid crystal monomers are a mixture of methyl methacrylate and 2-([l,l'-biphenyl]-2-oxyl)ethyl acrylate, the liquid crystal monomers are monomers of the structure shown in Formula 1, the film-forming resin is polyvinyl acetate, the photoinitiator is coumarin, and the solvent is tetrahydrofuran: cyclohexanone = 1:1.

[0081] The polymer composition is coated to form a thin film, which is dried to form a polymer thin film. The polymer thin film is then irradiated with coherent light to form an optical film material with a holographic grating structure. The thickness of the obtained optical film material is 10 μm.

[0082] Example 2

[0083] An optical film material is formed using a polymer composition. The polymer composition differs from that of Example 1 in that the composition of the polymer composition in this example is different from that of the polymer composition in Example 1.

[0084] The non-liquid crystal monomers are a mixture of methyl methacrylate and 4-biphenylmethanol acrylate, the liquid crystal monomers are monomers of the structure shown in Formula 2, and the film-forming resin is polyvinyl acetate.

[0085] Example 3

[0086] An optical film material is formed using a polymer composition. The polymer composition differs from that of Example 1 in that the composition of the polymer composition in this example is different from that of the polymer composition in Example 1.

[0087] The non-liquid crystal monomers are a mixture of methyl methacrylate and 4-biphenylmethanol acrylate, the liquid crystal monomers are monomers of the structure shown in Formula 3, and the film-forming resin is polymethyl methacrylate.

[0088] Example 4

[0089] An optical film is formed using a polymer composition. Compared with Example 1, the difference is that the composition of the polymer composition in this example is different from that in Example 1.

[0090] The non-liquid crystal monomer is a mixture of 2-N-morpholinoethyl methacrylate and 4-biphenylmethanol acrylate, the liquid crystal monomer is a monomer with the structure shown in Formula 4, and the film-forming resin is polyvinyl acetate.

[0091] Comparative Example 1

[0092] An optical film is formed using a polymer composition. Compared with Example 1, the difference is that the composition of the polymer composition in this example is different from that in Example 1, and the liquid crystal monomer in the polymer composition is replaced by a non-liquid crystal monomer.

[0093] The content of the non-liquid crystal monomer in the polymer composition in this comparative example is 49%, the content of the film-forming resin is 50%, the content of the photoinitiator is 1%, and the amount of solvent is appropriate. Among them, the substances of non-liquid crystal monomer, film-forming resin and photoinitiator are the same as in Example 1.

[0094] Comparative Example 2

[0095] An optical film is formed using a polymer composition. Compared with Example 2, the difference is that the composition of the polymer composition in this example is different from that in Example 2, and the liquid crystal monomer in the polymer composition is replaced by a non-liquid crystal monomer.

[0096] The content of the non-liquid crystal monomer in the polymer composition in this comparative example is 49%, the content of the film-forming resin is 50%, the content of the photoinitiator is 1%, and the amount of solvent is appropriate. Among them, the substances of non-liquid crystal monomer, film-forming resin and photoinitiator are the same as in Example 2.

[0097] Comparative Example 3

[0098] An optical film is formed using a polymer composition. Compared with Example 3, the difference is that the composition of the polymer composition in this example is different from that in Example 3, and the liquid crystal monomer in the polymer composition is replaced by a non-liquid crystal monomer.

[0099] The content of the non-liquid crystal monomer in the polymer composition in the comparative example is 49%, the content of the film-forming resin is 50%, the content of the photoinitiator is 1%, and the solvent is appropriate. Among them, the substances of the non-liquid crystal monomer, the film-forming resin and the photoinitiator are the same as those in Example 3.

[0100] Comparative Example 4

[0101] An optical film material is formed by using a polymer composition. Compared with Example 4, the difference is that the components of the polymer composition in the comparative example are different from those in Example 4, and the liquid crystal monomer in the comparative example is not contained, and the added amount of the liquid crystal monomer in the polymer composition is replaced by the added amount of the non-liquid crystal monomer.

[0102] The content of the non-liquid crystal monomer in the polymer composition in the comparative example is 49%, the content of the film-forming resin is 50%, the content of the photoinitiator is 1%, and the solvent is appropriate. Among them, the substances of the non-liquid crystal monomer, the film-forming resin and the photoinitiator are the same as those in Example 4.

[0103] Comparative Example 5

[0104] An optical film material is formed by using a polymer composition. Compared with Example 4, the difference is that the components of the polymer composition in the comparative example are different from those in Example 4, and the liquid crystal monomer in the comparative example is 4'-n-pentyl-4-cyanobiphenyl. The others are the same as those in Example 4.

[0105] The diffraction efficiency and the refractive index modulation degree and the haze of the optical film material of each example and the comparative example are tested respectively. The test results are shown in Table 1.

[0106] Among them, the diffraction efficiency test method is as follows: the ultraviolet visible spectrophotometer is used to measure the light transmittance of each example and the comparative example sample in the wavelength range of 400-800 nm, according to the obtained light transmittance curve, the minimum light transmittance (T min ) of the reflection peak and the light transmittance (T A ) of the baseline are obtained by using the light transmittance curve, and the diffraction efficiency η is calculated according to formula (5):

[0107] The refractive index modulation degree test method: the refractive index modulation degree (n1) can be calculated by the diffraction efficiency (η) and the thickness (d) of the film material.

[0108] Among them, λ is the test wavelength, and θ0 is the grating Bragg angle.

[0109] The haze test method: the haze can be directly measured by the haze meter.

[0110] Figure 1 is a graph of the light transmittance comparison test of the optical film material of Example 1 and Comparative Example 1. Figure 2 is a graph of the light transmittance comparison test of the optical film material of Example 2 and Comparative Example 2. Figure 3 is a graph of the light transmittance comparison test of the optical film material of Example 3 and Comparative Example 3. Figure 4 is a graph of the light transmittance comparison test of the optical film material of Example 4 and Comparative Example 4.

[0111] The performance parameters of the optical film material calculated from the test are listed in Table 1.

[0112] Table 1

[0113] From the data in Table 1, it can be seen that when the non-liquid crystal monomer is the same, the refractive index modulation of the optical film material in the examples of the present application can be significantly improved due to the addition of part of the liquid crystal monomer. Referring to the relevant data of Example 1 and Comparative Example 1, when part of the liquid crystal monomer is added, the diffraction efficiency of the optical film material of Example 1 is increased from 33.5% to 83.1%, an increase of 148%. Correspondingly, the refractive index modulation is increased by 156%. Referring to the relevant data of Example 2 and Comparative Example 2, Example 3 and Comparative Example 3, and Example 4 and Comparative Example 4, a large increase can be obtained. It can be proved that after adding a certain amount of liquid crystal monomer with polymerization characteristics in the high molecular composition system, the refractive index modulation of the optical film material can be improved.

[0114] In addition, from the relevant test data of Example 4 and Comparative Example 5 in Table 1, the haze of the optical film material of Example 4 is 0.9, while the haze of the optical film material of Comparative Example 5 is 2.7. This may be related to the aggregation position of the liquid crystal monomer. In the examples of the present application, the polymerizable liquid crystal monomer is polymerized under light conditions and performs phototaxis, gradually moving to the bright stripe area of the related stripes. Therefore, the polymerizable monomer in the examples of the present application will eventually copolymerize with the non-liquid crystal monomer to form the main polymer of the bright area, thereby affecting the optical performance of the optical film material. In Comparative Example 5, the small molecule liquid crystal monomer added therein cannot be polymerized under light conditions because it does not have a polymerizable active group. Therefore, it will be excluded to the dark area by the non-liquid crystal monomer with polymerization characteristics. At the same time, since the small molecule liquid crystal itself has a strong self-aggregation effect, it is more likely to aggregate in the film-forming resin when it is excluded by the non-liquid crystal monomer. The self-aggregation characteristics of the small molecule liquid crystal will cause it to form larger particles itself, thereby reducing the haze of the optical film material.

[0115] Based on the same technical purpose, the application further provides a display device, which comprises a substrate and the optical film material arranged on the substrate. The electronic device of the application, such as AR glasses, vehicle head-up display device, etc. Fig. 5 is a schematic structural diagram of AR glasses of an embodiment. As shown in Fig. 5, the AR glasses can comprise a lens, and the optical film material of the application can be arranged on the surface of the lens or between two lenses. The optical film material after exposure can be a holographic optical element, which records all the information of light, and can realize 3D stereoscopic projection. Combined with the high light transmittance of the optical film, the virtual and real can be combined. Fig. 6 is a schematic structural diagram of a vehicle head-up display device of an embodiment. As shown in Fig. 6, the optical film material of the application can be attached to the surface of the front windshield panel in the car, and through projection, the vehicle information display can be realized.

[0116] The above is only a specific embodiment of the application, but the protection scope of the application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical scope disclosed in the application, which should be covered in the protection scope of the application. Therefore, the protection scope of the application should be subject to the protection scope of the claims.

Claims

1. A high molecular composition, characterized by, The first polymerizable monomer, the second polymerizable monomer, and the film-forming resin; The first polymerizable monomer is a non-liquid crystal monomer; The second polymerizable monomer is a liquid crystal monomer, the second polymerizable monomer includes an active group and an aromatic group, and the second polymerizable monomer can copolymerize with the first polymerizable monomer through the active group under light irradiation.

2. The polymer composition according to claim 1, characterized in that The second polymerizable monomer further includes a non-active group, the non-active group includes at least one of a linear group with 1-20 carbon atoms, a branched group with 1-20 carbon atoms, and an aromatic group with 1-20 carbon atoms.

3. The polymer composition according to claim 1 or 2, characterized in that The active group of the second polymerizable monomer includes at least one of an acrylate group, a methacrylate group, an allyl group, a mercapto group, a hydroxyl group, a phenolic hydroxyl group, a carboxyl group, an alkyne group, an epoxy group, an oxetanyl group, a vinyl group, an amine group, and an acrylamide group.

4. The polymeric composition according to any one of claims 1 to 3, characterized in that, The mass ratio of the first polymerizable monomer to the second polymerizable monomer is 100:1-1:

100.

5. The polymeric composition according to any one of claims 1 to 4, characterized in that, The mass ratio of the second polymerizable monomer to the film-forming resin is 1:100-100:

10.

6. The polymeric composition according to any one of claims 1 to 5, characterized in that, The mass ratio of the film-forming resin to the total mass of the first polymerizable monomer and the second polymerizable monomer is 100:5-10:

100.

7. The polymeric composition according to any one of claims 1 to 6, characterized in that, The high polymer composition further includes a solvent and a photoinitiator.

8. The polymeric composition according to any one of claims 1 to 7, characterized in that, The film-forming resin does not include an aromatic group.

9. A high molecular film material, characterized by, The high polymer composition includes the high polymer film material.

10. A holographic grating, characterized by The high polymer film material is subjected to light irradiation treatment to obtain the holographic grating.

11. A holographic grating, characterized by The holographic grating includes a plurality of bright lines and a plurality of dark lines, the plurality of bright lines and the plurality of dark lines are arranged alternately, the bright lines include a linear polymer, the linear polymer has a molecular side chain provided with an aromatic group, the dark lines include a film-forming resin, and the refractive index modulation degree of the holographic grating is greater than 0.

01.

12. The holographic grating of claim 11, wherein, The number of the aromatic groups of the molecular side chain in each repeating unit of the linear polymer is 1-15.

13. The holographic grating according to claim 11 or 12, characterized in that, The aromatic group of the molecular side chain of the linear polymer includes at least one of a phenyl group, a biphenyl group, a naphthyl group, an anthracene group, a phenanthrene group, a carbazole group, a benzoic acid group, a hydroxybenzoic acid group, a phenol group, a quinone group, a furan group, a thiophene group, a pyrrole group, a thiazole group, a pyrazole group, an imidazole group, a pyridine group, a pyran group, a pyridine group, a pyrazine group, a quinoline group, an isoquinoline group, an indole group, a thiazine group, a purine group, and a pteridine group.

14. The holographic grating according to any of claims 11-13, wherein, The film-forming resin does not include an aromatic group.

15. The holographic grating according to any of claims 11-14, wherein, The film-forming resin is a cross-linked resin.

16. An optical film material, characterized by, The holographic grating includes a base film and the holographic grating arranged on the surface of the base film.

17. A method of producing a holographic grating, characterized by, The high polymer composition includes: The high polymer composition includes: a first polymerizable monomer, a second polymerizable monomer, and a film-forming resin; the first polymerizable monomer is a non-liquid crystal monomer; the second polymerizable monomer is a liquid crystal monomer, and the second polymerizable monomer includes an active group and an aromatic group; The second polymerizable monomer in the high polymer film material copolymerizes with the first polymerizable monomer through the active group under light irradiation to form the holographic grating.

18. A display device, characterized by An optical film as claimed in claim 16.

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