Chiral photopolymer composition, holographic grating and holographic device

Abstract

The invention provides a chiral photopolymer composition, a holographic grating and a holographic device. The chiral photopolymer composition comprises the following components: 20-30% of a photocuring monomer, 5-20% of a chiral compound, 0.6-10% of a photoinitiator system, 10-40% of a film-forming agent, 10-60% of a solvent and 0.1-10% of an optional additive. The chiral photopolymer composition provided by the invention can be polymerized under the induction of polarized light to obtain a chiral polymer, a holographic grating is endowed with certain polarization selectivity, and meanwhile, the uniformity, light transmission and refractive index modulation of the holographic grating can be improved, so that the application of the chiral photopolymer composition in the fields of light modulation, light display, light barrier, anti-counterfeiting and the like is expanded.

Description

Technical Field

[0001] The invention relates to the technical field of optical materials, and in particular to a chiral photopolymer composition, a holographic grating and a holographic device. Background Art

[0002] Holographic recording materials are a type of material that uses the principle of optical interference to record all the information of an object light wave (including amplitude and phase) in the form of interference fringes. In a typical processing method, a photopolymer composition is formed into an element by visible light laser irradiation, and the writing monomer used for holographic recording forms a (cured) polymer through polymerization reaction. As a result, structural features that can form interference patterns can be generated in the element formed by the photopolymer composition. At the same time, by modulating the refractive index, a phase hologram with high diffraction efficiency can be formed. Photosensitive / photopolymer materials have the characteristics of high sensitivity, high resolution, high signal-to-noise ratio, low cost, and simple processing technology. They are one of the most promising recording materials in the field of holographic devices.

[0003] The photosensitive / photopolymer system used as holographic recording material generally includes a photoinitiator, one or more monomers, a film former / liquid crystal, etc. When the holographic coherent light irradiates the uniform mixture of the photoinitiator, the monomer and the film former / liquid crystal, the photoinitiator generates an active center in the coherent bright area, which initiates the polymerization of the monomer, thereby causing the monomer to diffuse from the coherent dark area to the bright area until the reaction stops. The polymer in the bright area and the film former / liquid crystal in the dark area generate a refractive index difference, and finally form a holographic photopolymer with a sinusoidal distribution of chemical substances and refractive index, forming a phase-type hologram in the medium. Among them, the ordinary holographic photopolymer forms a refractive index difference between the polymer and the film former (n polymer>n film former), and the holographic polymer dispersed liquid crystal (HPDLC) forms a refractive index difference between the polymer and the liquid crystal (n liquid crystal>n polymer).

[0004] Ordinary holographic photopolymers do not have polarization selectivity, while HPDLC has certain polarization selectivity, which makes it more widely used in light modulation, light display, light blocking and anti-counterfeiting. However, the traditional preparation method of HPDLC is usually to heat the liquid HPDLC material to a clear point and then pour it into a liquid crystal box, followed by exposure and bleaching, and finally obtain a liquid crystal box sample with a small area, large thickness, and rigid and fragile structure. This process is complicated and not conducive to subsequent processing and transportation. In addition, the liquid crystal is easy to agglomerate, and the system controllability and stability are poor.

[0005] In view of this, there is an urgent need to develop a chiral photopolymer composition that can impart certain polarization selectivity to the holographic grating and has good controllability and stability. Summary of the invention

[0006] The main purpose of the present invention is to provide a chiral photopolymer composition to solve the problem that the existing holographic photopolymer has no polarization selectivity, while the holographic polymer dispersed liquid crystal has a certain polarization selectivity, but its preparation process is complicated and the system controllability and stability are poor.

[0007] In order to achieve the above-mentioned object, according to one aspect of the present invention, a chiral photopolymer composition is provided, which comprises the following components by mass percentage: 20-30% of a photocurable monomer, 5-20% of a chiral compound, 0.6-10% of a photoinitiator system, 10-40% of a film former, 10-60% of a solvent and 0.1-10% of an optional additive.

[0008] Furthermore, the chiral compound is at least one of a chiral agent and / or a chiral monomer, and the chiral agent includes at least one of R5011, S5011, R1011, S1011, R811, S811, CB15, R2011, S2011, CM19, CM20, and CM22.

[0009] Furthermore, the chiral monomer contains a chiral group, and the chiral monomer has a structure as shown in the following formula (I):

[0010]

[0011] Wherein, M represents a chiral group; Q' represents an epoxy group or a (meth)acryloyl group, n represents an integer between 1 and 3; X' represents a direct bond, a substituted or unsubstituted C1-C16 alkylene group, or a substituted or unsubstituted C1-C16 alkyleneoxy group; Y' represents a direct bond, a substituted or unsubstituted aromatic ring, a substituted or unsubstituted cyclohexylene group, a substituted or unsubstituted cyclopentylene group, a methylene group, an oxy group, or a sulfenyl group; and m represents 1 or 2.

[0012] Furthermore, M is represented by [Z'(R') p ]*, wherein Z' represents a carbon atom, a carbon-carbon single bond, a carbon-carbon double bond, or a nitrogen-nitrogen double bond; p represents an integer between 1 and 3; R' represents at least one of H, halogen, nitro, hydroxyl, C1-C20 alkyl, C1-C20 alkoxy, C6-C20 aryl, and C5-C20 heteroaryl, and when p>2, each R' is different.

[0013] Furthermore, R' represents one of the following groups formed from rigid compounds: benzene, naphthalene, benzocyclohexane, fluorene, benzothiophene, azobenzene, cyclohexene, cyclopentene, and styrene.

[0014] Further, M represents at least one of the chiral groups generated by the following chiral substances: L / D-leucine, L / D-lysine, L / D-glutamic acid, L / D-alanine, L / D-benzoic acid, S-2-methyl-1-butanol, γ-substituted-γ-butyrolactone, δ-substituted-δ-valerolactone, azobenzene, binaphthyl, diarylethene, vinyldicyclohexane, and arylvinonitrile.

[0015] Further, the chiral monomer is selected from at least one of 4-acryloylundecanyloxy-4'-(S(-)-2-methylbutyloxy)-binaphthyl and 4-acryloyloxybenzoyloxycholesteryl acetate.

[0016] Furthermore, the photocurable monomer has a structure as shown in the following formula (II):

[0017] (Q) q —X——A——Y—B—Z

[0018] Formula (II)

[0019] In formula (II), Q represents an epoxy group or a methacryloyl group, q represents an integer between 1 and 3; X represents a direct bond, a substituted or unsubstituted C1-16 alkylene group, or a substituted or unsubstituted C1-C16 alkyleneoxy group; Y represents a direct bond, a substituted or unsubstituted arylene group, a para-aryldi(acyl)oxy group, *CH2*, *C(CH3)2*, *CH2-CH2*, *CH=CH*, *C≡C*, *CH=N*, *N=N*, *N(O)*; A and B each independently represent a substituted or unsubstituted arylene group, or a substituted or unsubstituted cyclohexylene group; Z represents H, halogen, amino, cyano, isocyano, amino, substituted or unsubstituted C1-C20 alkyl group, substituted or unsubstituted C1-C20 alkoxy group, C1-C20 ester group, or substituted or unsubstituted C1-C20 ether group.

[0020] Furthermore, the photocurable monomer is selected from at least one of RM257, RM82 or 2,2-bis(4-epoxypropoxyphenyl)propane.

[0021] Furthermore, the photoinitiator system includes a photoinitiator and a co-initiator, and the mass ratio of the two is (0.1-5):(0.5-5).

[0022] Furthermore, the initiator includes at least one of Irgacure 784, Basic Red 2, Dioscorea Red Y, Methylene Blue, Rhodamine 6G, Diiodofluorescein, Aminocoumarin, Tetraphenylborate, Triphenyl-n-butylborate, 2-isopropylthioxanthone, and ethyl 4-dimethylaminobenzoate.

[0023] Furthermore, the co-initiator includes at least one of triethanolamine, methyldiethanolamine, butyldiethanolamine, N-phenylglycine, and 2-(4-chlorophenyl)-4,5-diphenylimidazole.

[0024] Furthermore, the film-forming agent is a polymer, the number average molecular weight of the polymer is 1000-2000000, and the refractive index of the film-forming agent is ≤1.480.

[0025] Furthermore, the film-forming agent includes at least one of cellulose ester, cellulose ether, polyvinyl alcohol, polyvinyl acetal, polyurethane, styrene-butadiene copolymer, polyvinyl pyrrolidone, vinyl acetate homopolymer, vinyl acetate-acrylate copolymer, vinyl acetate-ethylene copolymer, and vinyl acetate-styrene copolymer.

[0026] Furthermore, the solvent is a non-reactive solvent, preferably at least one of a halogenated hydrocarbon solvent, a ketone solvent, an alcohol solvent, an ester solvent, a hydrocarbon solvent, and an amide solvent; and / or the additive includes at least one of a dye, a polar solvent, a plasticizer, a toughening agent, an inhibitor, a light stabilizer, a chain transfer agent, a leveling agent, a wetting agent, a defoamer, a tackifier, an oligomer, a compound having a hydrophilic group, and an oxygen-containing compound.

[0027] According to another aspect of the present invention, a holographic grating is provided. The holographic grating comprises a polymer film having a grating structure, and the material of the polymer film is the chiral photopolymer composition provided in the first aspect.

[0028] Furthermore, the method for preparing the polymer film includes the following steps: step S1, mixing a photocurable monomer, a chiral compound, a photoinitiator system, a film-forming agent, a solvent and optional additives to obtain a mixture; step S2, preparing the mixture into a film to be cured; step S3, forming a grating structure on at least a part of the film to be cured to obtain a polymer film with a grating structure.

[0029] Further, step S3 includes the step of performing exposure using coherent light.

[0030] According to a third aspect of the present invention, there is also provided a holographic device, which comprises the holographic grating provided by the second aspect.

[0031] By applying the technical solution of the present application, the chiral photopolymer composition provided by the present application can be polymerized under the induction of polarized light to obtain a chiral polymer, and endow the holographic grating with a certain polarization selectivity, while improving the uniformity, light transmittance and refractive index modulation of the holographic grating, thereby expanding its application in the fields of light modulation, light display, light blocking and anti-counterfeiting.

[0032] In addition, the preparation method of the chiral photopolymer composition induced to form a holographic grating provided in the present application is simple, is conducive to batch production and processing, and has the advantages of good controllability and good stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0034] Figure 1 shows polarization selectivity curves of holographic gratings provided according to embodiments 1-4 of the present invention and comparative examples 1-3; and

[0035] Figure 2 shows polarization selectivity curves of holographic gratings provided according to Examples 5-7 of the present invention and Comparative Examples 4-5; and

[0036] Figure 3 Curves showing the change of polarization selectivity of the holographic gratings provided by Examples 1-7 and Comparative Examples 4-5 with storage time are shown. DETAILED DESCRIPTION

[0037] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments.

[0038] In the present application, the term "substituted or unsubstituted" refers to substitution by one or more substituents selected from the following: deuterium; halogen group; nitrile group; nitro group; hydroxyl group; carbonyl group; ester group; imide group; amino group; phosphine oxide group; alkoxy group; aryloxy group; alkylthio group; arylthio group; alkylsulfonyl group; silyl group; boron group; alkyl group; cycloalkyl group; alkenyl group; aryl group; aralkyl group; aralkenyl group; alkylaryl group; alkylamino group; aralkylamino group; heteroarylamino group; arylamino group; arylphosphino group; or a heterocyclic group containing at least one of N, O and S, or no substituent, or substituted by substituents connected by two or more substituents among the exemplified substituents, or no substituent. For example, the term "substituents connected by two or more substituents" can be a biphenyl group. That is, the biphenyl group can be an aryl group, or it can be interpreted as a substituent connected by two phenyl groups.

[0039] In addition, the range of carbon number in this article can be extended from the lower limit to the upper limit, for example, C6-C20 means that the carbon number can be 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20.

[0040] In this application, "*" represents a connecting bond.

[0041] As analyzed in the background technology of this application, the existing holographic photopolymers do not have polarization selectivity, while holographic polymer dispersed liquid crystals have certain polarization selectivity, but their preparation process is complicated, and the system controllability and stability are poor. In order to solve this problem, this application provides a chiral photopolymer composition, a holographic grating and a holographic device.

[0042] In the first typical embodiment of the present application, a chiral photopolymer composition is also provided, which comprises the following components by mass percentage: 20-30% photocurable monomer, 5-20% chiral compound, 0.6-10% photoinitiator system, 10-40% film former, 10-60% solvent and 0.1-10% optional additives.

[0043] In the photopolymer composition provided in the present application, the mass content of the polymer composition is 20%, 22%, 25%, 25%, 28%, 30% or a range consisting of any two values; the mass content of the chiral compound is 5%, 8%, 10%, 12%, 15%, 18%, 20% or a range consisting of any two values; the mass content of the photoinitiator system is 0.6%, 0.8%, 1%, 1.5%, 2%, 5%, 8%, 10% or a range consisting of any two values. The mass content of the film-forming agent is 10%, 15%, 20%, 25%, 30%, 35%, 40% or a range consisting of any two numerical values; the mass content of the solvent is 10%, 15%, 20%, 30%, 40%, 50%, 60% or a range consisting of any two numerical values; the mass content of the additive is 0, 0.1%, 0.2%, 0.5%, 1%, 2%, 5%, 8%, 10% or a range consisting of any two numerical values.

[0044] [Chiral Compounds]

[0045] The chiral compound is at least one of a chiral agent and / or a chiral monomer. The chiral agent is an optical substance that can induce the photocurable monomer to form a spiral arrangement during photocuring, including but not limited to one or a mixture of two or more chiral agents selected from R5011, S5011, R1011, S1011, R811, S811, CB15, R2011, S2011, CM19, CM20, and CM22.

[0046] The chiral agent can be purchased from Beijing Bayi Space-Time Liquid Crystal Technology Co., Ltd. or Shijiazhuang Stiano Fine Chemical Co., Ltd.

[0047] The chiral monomer is a monomer containing a chiral group, which can induce the photocurable monomer to form a spiral arrangement during photocuring through the chiral monomer, and the chiral monomer can also participate in the polymerization reaction, thereby making the prepared holographic grating have better stability.

[0048] The chiral monomer has a structure as shown in the following formula (I):

[0049]

[0050] In formula (I), M represents a chiral group; Q' represents an epoxy group or an acryloyl group, n represents an integer between 1 and 3; X' represents a direct bond, a substituted or unsubstituted C1-C16 alkylene group, or a substituted or unsubstituted C1-C16 alkyleneoxy group; Y' represents a direct bond, a substituted or unsubstituted aromatic ring, a substituted or unsubstituted cyclohexylene group, a substituted or unsubstituted cyclopentylene group, a methylene group, an oxy group, or a sulfenyl group; and m represents 1 or 2.

[0051] The above-mentioned acryloyl group includes both unsubstituted acryloyl group and acryloyl group substituted with a substituent, such as methacryloyl group and the like.

[0052] In some embodiments, M is represented by [Z'(R') p ]*, wherein Z' represents a carbon atom, a carbon-carbon single bond, a carbon-carbon double bond, or a nitrogen-nitrogen double bond; p represents an integer between 1 and 3; R' represents at least one of H, halogen, nitro, hydroxyl, C1-C20 alkyl, C1-C20 alkoxy, C6-C20 aryl, and C5-C20 heteroaryl, and when p>2, each R' is different. In particular, when R' represents one of the following groups generated by rigid compounds: benzene, naphthalene, benzocyclohexane, fluorene, benzothiophene, azobenzene, cyclohexene, cyclopentene, and styrene; the helical twisting force of the chiral monomer is higher, thereby improving the polarization selectivity of the holographic grating, and at the same time, it can also increase the refractive index of the chiral monomer, thereby improving the refractive index modulation of the holographic grating.

[0053] In other embodiments, M represents at least one of the chiral groups generated by the following chiral substances: L / D-leucine, L / D-lysine, L / D-glutamic acid, L / D-alanine, L / D-benzoic acid, S-2-methyl-1-butanol, γ-substituted-γ-butyrolactone, δ-substituted-δ-valerolactone, azobenzene, binaphthyl, diarylethene, vinyldicyclohexane, and aromatic vinyl nitrile.

[0054] The chiral monomers include, but are not limited to, 4-acryloylundecanyloxy-4′-(S(-)-2-methylbutyloxy)-binaphthyl or 4-acryloyloxybenzoyloxyacetic acid cholesteryl ester.

[0055] It is worth mentioning that in order to increase the helical torsion force, chiral agents or chiral monomers usually contain highly rigid structures of polyaromatic rings, but such structures will cause the solubility of chiral agents or chiral monomers in the photopolymer mixture system to decrease, and the uniformity and light transmittance of the system will also decrease accordingly. Compared with chiral agents, chiral monomers are connected with flexible chains containing epoxy or (meth) acryloyl groups, and their structures similar to monomers can greatly improve the solubility of chiral monomers and the system, and improve the uniformity and light transmittance of the holographic grating formed by the final chiral photopolymer composition. In addition, chiral monomers can participate in the photopolymerization reaction and combine with the final superhelical chiral polymer macromolecules through chemical bonds, which has a greater anchoring force and makes the overall structure more stable.

[0056] [Photocurable monomer]

[0057] In some embodiments, the photocurable monomer has a structure as shown in the following formula (II):

[0058] (Q) q —X—A——Y——B—Z

[0059] Formula (II)

[0060] In formula (II), Q represents an epoxy group or an acryloyl group, q represents an integer between 1 and 3; X represents a direct bond, a substituted or unsubstituted C1-16 alkylene group, or a substituted or unsubstituted C1-C16 alkyleneoxy group; Y represents a direct bond, a substituted or unsubstituted arylene group, a para-aryldi(acyl)oxy group, *CH2*, *C(CH3)2*, *CH2-CH2*, *CH=CH*, *C≡C*, *CH=N*, *N=N*, *N(O)*;

[0061] The above-mentioned acryloyl group includes both unsubstituted acryloyl group and acryloyl group substituted with a substituent, such as methacryloyl group and the like.

[0062] A and B each independently represent a substituted or unsubstituted arylene group, a substituted or unsubstituted cyclohexylene group; Z represents H, halogen, amino, cyano, isocyano, amino, substituted or unsubstituted C1-C20 alkyl group, substituted or unsubstituted C1-C20 alkoxy group, C1-C20 ester group, or substituted or unsubstituted C1-C20 ether group.

[0063] In some specific embodiments, the photocurable monomer is selected from any one or a mixture of RM257 (Anhui Zesheng Technology Co., Ltd. / Annaiji Chemical), RM82 or 2,2-bis(4-epoxypropoxyphenyl)propane.

[0064] [Photoinitiator system]

[0065] In order to further improve the photoinitiation efficiency, the above-mentioned photoinitiation system preferably includes a photoinitiator and a co-initiator, and the mass ratio of the two is (0.1-5):(0.5-5), such as the mass ratio of the photoinitiator to the co-initiator is 0.1:0.5, 0.1:1, 0.1:2, 0.1:3, 0.1:4, 0.1:5, 0:2:0.5, 0.2:1, 0.2:2, 0.2:3, 0.2:4, 0.2:5, 0.5:0.5, 0.5:1, 0.5:2, 0.5:3, 0.5:4, 0.5:5, 1:0.5, 1:2, 1:3, 1:4, 1:5, 2:0.5, 2:0.5, 2:1, 2:3, 2:5, 5:0.5, 5:1, 5:2, 5:3, 5:4 or a range consisting of any two numerical values.

[0066] Photoinitiators are photosensitive compounds that absorb light of a specific wavelength and, through a series of chemical processes, generate active species capable of initiating polymerization. Depending on the type of active center generated after photolysis, photoinitiators can be divided into free radical photoinitiators, photoacid generators (cationic photoinitiators) and photobase generators.

[0067] There is no particular limitation on the free radical photoinitiator suitable for the present application, but it is preferably a visible light photosensitizer having photoinitiating activity, and suitable photosensitizers are, for example, Irgacure 784, new methylene blue, thionine, basic red 2, basic yellow, chlorinated pinacol cyanol, rhodamine 6G, biscyanine, ethyl violet, Victoria blue R, azure blue, quinaldine red, crystal violet, brilliant green, astrazon orange G, darrow red, pyronine Y, Bengal rose red, potato red Y, Michler's ketone, aminocoumarin, pyrillium I, diiodofluorescein, anthocyanin, methylene blue, 2,5-bis{[4-(diethylamino)-2-methylphenyl]methylene}cyclopentanone, crystal violet (leuconitrile) or malachite green (leuconitrile), etc. These substances can be used alone or in combination of two or more.

[0068] Cationic photoinitiators suitable for the present application include diazonium salts, diaryliodonium salts, triarylsulfonium salts, alkylsulfonium salts, iron arene salts, sulfonyloxy ketones and triarylsiloxane ethers.

[0069] The photobase generator suitable for the present application includes carbamate, aminoketone, benzoylformamide, cobalt amine complex, quaternary ammonium salt, tetraphenyl boron salt, carboxylate and the like.

[0070] In some preferred embodiments of the present application, the photoinitiator suitable for the present invention is selected from at least one of Irgacure784, Basic Red 2, Potato Red Y, Methylene Blue, Rhodamine 6G, Diiodine Fluorescein, Aminocoumarin, Tetraphenylborate, Triphenyl-n-butylborate, 2-isopropylthioxanthone, and 4-dimethylaminobenzoic acid ethyl ester.

[0071] There is no particular limitation on the co-initiator suitable for the present application, but it is preferably an initiator-active compound containing a N atom. Examples of the co-initiator include at least one of triethanolamine, methyldiethanolamine, butyldiethanolamine, N-phenylglycine, and 2-(4-chlorophenyl)-4,5-diphenylimidazole.

[0072] [Film-forming agent]

[0073] There is no particular limitation on the film-forming agent used in the present application, but it is preferably a polymer with a number average molecular weight of 1000 to 200000 and having a certain adhesiveness. Preferably, these materials have a relatively low refractive index, and in some specific embodiments, the refractive index of these materials is below 1.480.

[0074] Typically but not limiting, the number average molecular weight of the above-mentioned film-forming polymer is 1000, 2000, 5000, 8000, 10000, 15000, 20000, 50000, 80000, 100000, 120000, 150000, 200000 or a range consisting of any two values.

[0075] In the present application, the film-forming agent includes, but is not limited to, vinyl acetate homopolymer, vinyl acetate-acrylate copolymer, vinyl acetate-ethylene copolymer, vinyl acetate-styrene copolymer, cellulose ester (such as cellulose acetate, cellulose acetate-succinate, cellulose acetate-butyrate, etc.), cellulose ether (such as methyl cellulose, ethyl cellulose and benzyl cellulose, etc.), polyvinyl alcohol, polyvinyl acetal (such as polyvinyl butyral, polyvinyl formal, etc.); polyurethane (usually obtained by the reaction of polyols and isocyanates, polyols such as polytetrahydrofuran, polyethylene glycol, polypropylene glycol, castor oil, isocyanates such as hexamethylene-1,6-diisocyanate, 1,4-cyclohexane diisocyanate, methyl-2,4-diisocyanate), styrene-butadiene block copolymers, polyvinyl pyrrolidone, any one or a mixture of two or more thereof.

[0076] [Solvent]

[0077] The raw materials of various compositions provided in the present application are mixed with a solvent to form a uniform system. The solvent of the present application is preferably a non-reactive solvent component.

[0078] There is no particular limitation on the types of solvents suitable for the present application. Conventional organic solvents in the art can be used, including halogenated hydrocarbon solvents (such as dichloromethane, dichloroethane, chloroform, etc.), ketone solvents (such as acetone, butanone, etc.), alcohol solvents (such as ethanol, butanol, etc.), ester solvents (such as ethyl acetate, butyl acetate, etc.), hydrocarbon solvents (such as aliphatic hydrocarbon solvents or aromatic hydrocarbon solvents, etc.), and amide solvents [such as DMAC (dimethylacetamide), DMF (N,N-dimethylformamide), etc.].

[0079] [additive]

[0080] In the present application, as long as it does not affect the technical effects of the present application, other ingredients commonly used in the art can be used according to actual production needs. These ingredients include: dyes, chain transfer agents, plasticizers, leveling agents, wetting agents, defoamers or tackifiers, as well as polyurethanes, thermoplastic polymers, other oligomers, compounds with additional functional groups (such as acetals, epoxides, oxetanes, oxazolines, dioxolanes) and / or compounds with hydrophilic groups (such as salts and / or polyethylene oxides) can all be used as additives.

[0081] In addition, in order to increase the refractive index modulation, optically inactive high refractive index compounds, such as metal oxide nanoparticles, can also be added.

[0082] In a second typical embodiment of the present application, a holographic grating is provided. The holographic grating includes a polymer film having a grating structure, and the material of the polymer film is the chiral photopolymer composition provided in the first typical embodiment.

[0083] The holographic grating provided in the present application is prepared using the above-mentioned chiral photopolymer composition, which not only has a certain polarization selectivity, but also can improve the uniformity, light transmittance and refractive index modulation of the holographic grating, thereby expanding its application in the fields of light modulation, light display, light blocking and anti-counterfeiting.

[0084] In some embodiments, the method for preparing a polymer film includes the following steps: step S1, mixing a photocurable monomer, a chiral compound, a photoinitiator system, a film-forming agent, a solvent and optional additives to obtain a mixture; step S2, preparing a photocurable chiral polymer solution into a film to be cured; step S3, forming a grating structure on at least a portion of the film to be cured to obtain a polymer film having a grating structure.

[0085] In order to further improve the preparation efficiency of the polymer film with a grating structure, it is preferred that step S3 includes a step of using coherent light for exposure to improve the formation efficiency of the grating.

[0086] <Step S1>

[0087] In some specific embodiments of the present application, step S1 is to obtain a mixture in a melt or liquid state, ie, a mixture, by mixing the chiral photopolymer composition.

[0088] The chiral photopolymer composition can be mixed in a suitable container according to the proportion, and mechanical stirring or the like can be used to make the mixture uniform when necessary. There is no particular restriction on the mixing temperature, and the mixing can usually be carried out at room temperature or under heating (preheating).

[0089] In some other specific embodiments, the mixing step can be carried out under appropriate heating conditions. The heating temperature can be determined according to the activity of each component in the chiral photopolymer composition and the desired viscosity of the system. Under some conditions, it is necessary to increase the mixing temperature to obtain a lower viscosity to obtain a chiral photopolymer solution in which each component is uniformly mixed. In addition, it is also necessary to control the degree of heating so as not to be overheated to avoid excessive polymerization or structural mutation in unnecessary processing windows.

[0090] In some preferred embodiments of the present application, the temperature used in the mixing step is above 10° C. and below 90° C., preferably below 60° C. The obtained chiral photopolymer solution can be used immediately or stored briefly at the processing temperature for use.

[0091] In addition, to prevent curing during the mixing process, the addition of dyes and co-initiators should be done last and in a dark room or under a protective light environment that is inert to the dye.

[0092] <Step S2>

[0093] In this step, the chiral photopolymer solution obtained above is used to form a film on a carrier, and then processed into the shape and size required for subsequent operations. In some specific embodiments, step S2 includes:

[0094] Step S21, in a dark room or under a protective light environment, the chiral photopolymer solution is coated on glass, plastic film or other substrates, and a device known to those skilled in the art such as a doctor blade, a knife roller, a curved rod (Commabar, etc.) or a slit nozzle can be used.

[0095] Step S22, leaving the solvent to evaporate, the temperature may be appropriately increased to increase the evaporation rate, or the process may be performed at room temperature and low pressure or in a blowing environment.

[0096] Step S23, after the solvent is completely removed, a film to be cured is obtained, another layer of protective film is covered on the surface of the film to be cured, and then it is cut into appropriate sizes to obtain a photopolymer dry plate, which is stored away from light for future use.

[0097] <Step S3>

[0098] In this step, the photopolymer dry plate obtained above is subjected to an exposure process to obtain a photopolymer film having a grating structure. In some embodiments, the specific operation of step S3 is as follows:

[0099] Step S31, exposing the photopolymer dry plate obtained in step S23 by interference exposure with two circularly polarized beams in a dual-beam optical path to form a photopolymer holographic grating; a high laser intensity and short exposure time mode is used;

[0100] Step S32, irradiating the photopolymer holographic grating obtained in step S31 with an LED lamp, a fluorescent lamp or an ultraviolet lamp until it is completely fixed and bleached, thereby obtaining a photopolymer film having a grating structure.

[0101] In some specific embodiments of the present application, two beams of coherent light can simultaneously expose the polymer film from one side (transmission grating); in other specific embodiments, two beams of coherent light can expose the polymer from both sides of the polymer film respectively (reflection grating).

[0102] In addition, the holographic grating obtained in the present application can be a plane grating or a curved grating with a certain curvature. There is no particular limitation on the method for preparing the curved grating. In some specific embodiments, a substrate with a certain curvature can be used, and a film can be formed on the substrate and exposed. In some other specific schemes, a plane substrate can also be used, and the coating film can be processed into a curved grating with a certain curvature after exposure.

[0103] In a third typical embodiment of the present application, a holographic device is further provided. The holographic device includes the holographic grating provided in the second typical embodiment.

[0104] Without limitation, the grating containing the photopolymer film described above in the present application can be used in various holographic display systems in the art, and can be used alone or in combination with other optical elements.

[0105] In some preferred embodiments, the present application provides a diffraction grating element for a holographic optical waveguide display system. The element includes a carrier and a polymer film having a grating structure. The polymer film having a grating structure is the same as the polymer film having a grating structure in the second typical embodiment described above, and will not be described in detail here.

[0106] The beneficial effects of the present application will be further illustrated below in combination with embodiments and comparative examples.

[0107] Example 1

[0108] This embodiment provides a holographic grating, which is prepared from a chiral photopolymer composition. The composition of the chiral photopolymer composition is shown in Table 1 below.

[0109] The holographic grating is prepared according to the following steps:

[0110] (1) Add photocurable monomer RM257 (Annaiji), chiral agent R5011 (Shijiazhuang Stiano), film-forming agent cellulose acetate butyrate, plasticizer dibutyl phthalate, and solvent butyl acetate into a sample bottle, stir at room temperature until completely clear, then add initiator eosin Y, N-phenylglycine and 2-(4-chlorophenyl)-4,5-diphenylimidazole under light-proof or red light and stir for 30 minutes to obtain a uniform and clear photoinduced chiral polymer solution.

[0111] (2) The mixed solution is then coated on glass in a dark or red light environment and baked at 60°C for 10 min to form a film to be cured. A TAC (triacetyl cellulose) protective film is then covered on the surface of the film to be cured to obtain a photopolymer dry plate.

[0112] (3) The resulting dry plate was heated in a dual beam path with an energy density of 15 mJ / cm 2 The holographic grating is formed by 532nm laser interference exposure and UV (ultraviolet light) lamp irradiation for about 30 minutes for fixing and bleaching.

[0113] Table 1

[0114]

[0115]

[0116] Example 2

[0117] This embodiment provides a holographic grating, which is prepared from a chiral photopolymer composition. The composition of the chiral photopolymer composition is shown in Table 2 below.

[0118] The holographic grating is prepared according to the following steps:

[0119] (1) Add photocurable monomer RM257, 2,2-bis(4-epoxypropoxyphenyl)propane, chiral agent R811 (Shijiazhuang Stiano), film former cellulose acetate butyrate, plasticizer dibutyl phthalate, solvent butyl acetate into a sample bottle, stir at room temperature until completely clear, then add initiator aminocoumarin and N-phenylglycine under light-proof or red light and stir for 30 min to obtain a uniform and clear photoinduced chiral polymer solution.

[0120] (2) Then, the photoinduced chiral polymer solution is coated on glass in a dark or red light environment, and is baked at 60° C. for 10 min to form a to-be-cured film. The surface of the to-be-cured film is covered with a TAC protective film to obtain a photoinduced polymer dry plate.

[0121] (3) The resulting photopolymer dry plate was subjected to a double beam optical path with an energy density of 15 mJ / cm 2 The 450nm laser interference exposure is followed by UV lamp irradiation for about 30 minutes for fixing and bleaching to form a holographic grating.

[0122] Table 2

[0123]

[0124]

[0125] Example 3

[0126] This embodiment provides a holographic grating, which is prepared from a chiral photopolymer composition. The composition of the chiral photopolymer composition is shown in Table 3 below.

[0127] The holographic grating is prepared according to the following steps:

[0128] (1) Add photocurable monomer RM82 (Annaiji), chiral monomer 4-acryloyl undecyloxy-4'-(S(-)-2-methylbutyloxy)-binaphthyl, film-forming agent cellulose acetate butyrate, plasticizer dibutyl phthalate, solvent butyl acetate into a sample bottle, stir at room temperature until completely clear, add initiator aminocoumarin and N-phenylglycine in dark or red light and stir for 30 minutes to obtain a uniform and clear photoinduced chiral polymer solution.

[0129] (2) Then, the mixed solution is coated on glass in a dark or red light environment, and baked at 60° C. for 10 min to form a film to be cured. The surface of the film to be cured is covered with a TAC protective film to obtain a photopolymer dry plate.

[0130] (3) The resulting photopolymer dry plate was subjected to a double beam optical path with an energy density of 15 mJ / cm 2 The 450nm laser interference exposure is followed by UV lamp irradiation for about 30 minutes for fixing and bleaching to form a holographic grating.

[0131] Table 3

[0132]

[0133] Example 4

[0134] This embodiment provides a holographic grating, which is prepared from a chiral photopolymer composition. The composition of the chiral photopolymer composition is shown in Table 4 below.

[0135] The holographic grating is prepared according to the following steps:

[0136] (1) Add photocurable monomer RM82 (Annaiji), chiral monomer 4-acryloyloxybenzoyloxyacetic acid cholesteryl ester, film former cellulose acetate butyrate, plasticizer dibutyl phthalate, solvent butyl acetate into a sample bottle, stir at room temperature until completely clear, add initiator aminocoumarin and N-phenylglycine in dark or red light and stir for 30 minutes to obtain a uniform and clear photoinduced chiral polymer solution.

[0137] (2) Then, the mixed solution is coated on glass in a dark or red light environment, and baked at 60° C. for 10 min to form a film to be cured. The surface of the film to be cured is covered with a TAC protective film to obtain a photopolymer dry plate.

[0138] (3) The resulting photopolymer dry plate was subjected to a double beam optical path with an energy density of 15 mJ / cm 2 The 450nm laser interference exposure is followed by UV lamp irradiation for about 30 minutes for fixing and bleaching to form a holographic grating.

[0139] Table 4

[0140] composition Quality content Aminocoumarin 0.2％ N-phenylglycine 0.8％ RM82 25％ 4-Acryloyloxybenzoyloxyacetic acid cholesteryl ester 10％ Cellulose acetate butyrate 22％ Dibutyl phthalate 5％ Butyl acetate 37％

[0141] Comparative Example 1

[0142] This comparative example provides a holographic grating, which is prepared from a chiral photopolymer composition. The composition of the chiral photopolymer composition is shown in Table 5 below.

[0143] The preparation method of the holographic grating is the same as that in Example 1, and will not be described in detail here.

[0144] Table 5

[0145] composition Quality content Eosin Y 0.2％ N-phenylglycine 0.8％ 2-(4-Chlorophenyl)-4,5-diphenylimidazole 1％ RM257 25％ Cellulose acetate butyrate 20％ Dibutyl phthalate 5％ Butyl acetate 48％

[0146] Comparative Example 2

[0147] This comparative example provides a holographic grating, which is prepared from a chiral photopolymer composition. The composition of the chiral photopolymer composition is shown in Table 6 below.

[0148] The preparation method of the holographic grating is the same as that in Example 1, and will not be described in detail here.

[0149] Table 6

[0150] composition content Aminocoumarin 0.2％ N-phenylglycine 0.8％ RM257 20％ 2,2-Bis(4-glycidoxyphenyl)propane 5％ Cellulose acetate butyrate 22％ Dibutyl phthalate 10％ Butyl acetate 42％

[0151] Comparative Example 3

[0152] This comparative example provides a holographic grating, which is prepared from a chiral photopolymer composition. The composition of the chiral photopolymer composition is shown in Table 7 below.

[0153] The preparation method of the holographic grating is the same as that in Example 1, and will not be described in detail here.

[0154] Table 7

[0155] composition Quality content Aminocoumarin 0.2％ N-phenylglycine 0.8％ RM82 25％ Cellulose acetate butyrate 22％ Dibutyl phthalate 5％ Butyl acetate 47％

[0156] Example 5

[0157] This embodiment provides a holographic grating, which is prepared from a chiral photopolymer composition. The composition of the chiral photopolymer composition is shown in Table 8 below.

[0158] The preparation method of the holographic grating is the same as that in Example 1, and will not be described in detail here.

[0159] Table 8

[0160] composition Quality content Aminocoumarin 0.2％ N-phenylglycine 0.8％ RM82 25％ R811 10％ Cellulose acetate butyrate 22％ Dibutyl phthalate 5％ Butyl acetate 37％

[0161] Example 6

[0162] This embodiment provides a holographic grating, which is prepared from a chiral photopolymer composition. The composition of the chiral photopolymer composition is shown in Table 9 below.

[0163] The preparation method of the holographic grating is the same as that in Example 1, and will not be described in detail here.

[0164] Table 9

[0165] composition Quality content Aminocoumarin 0.2％ N-phenylglycine 0.8％ RM82 30％ R811 20％ Cellulose acetate butyrate 14％ Dibutyl phthalate 5％ Butyl acetate 10％

[0166] Example 7

[0167] This embodiment provides a holographic grating, which is prepared from a chiral photopolymer composition, and the composition of the chiral photopolymer composition is shown in Table 10. The preparation method of the holographic grating is the same as that in Example 1, and will not be repeated here.

[0168] Table 10

[0169] composition Quality content Aminocoumarin 0.2％ N-phenylglycine 0.4％ RM82 20％ R811 5％ Cellulose acetate butyrate 10％ Dibutyl phthalate 4.4％ Butyl acetate 60％

[0170] Comparative Example 4

[0171] This embodiment provides a holographic grating, which is prepared from a chiral photopolymer composition. The composition of the chiral photopolymer composition is shown in Table 11 below.

[0172] The preparation method of the holographic grating is the same as that in Example 1, and will not be described in detail here.

[0173] Table 11

[0174] composition Quality content Eosin Y 0.2％ N-phenylglycine 0.8％ 2-(4-Chlorophenyl)-4,5-diphenylimidazole 1％ RM257 25％ R5011 3％ Cellulose acetate butyrate 20％ Dibutyl phthalate 5％ Butyl acetate 45％

[0175] Comparative Example 5

[0176] This embodiment provides a holographic grating, which is prepared from a chiral photopolymer composition. The composition of the chiral photopolymer composition is shown in Table 12 below.

[0177] The preparation method of the holographic grating is the same as that in Example 1, and will not be described in detail here.

[0178] Table 12

[0179]

[0180]

[0181] Test Example 1

[0182] The diffraction efficiency of the diffracted light obtained by the photopolymer grating obtained in the above embodiments and comparative examples was tested by a single beam of polarized light incident thereon. The results are shown in Table 13 below.

[0183] The specific test method for diffraction efficiency is as follows: use a laser with the same original exposure wavelength to pass through the center of the grating, use a power meter to test the power of the incident light and the transmitted light, slowly adjust the sample angle and record the transmitted light power, calculate the transmittance curve of the grating, and then calculate the light absorption by fitting. The total incident light power minus the transmitted light and absorbed light power is the diffraction light power, and the value of diffraction light power / total incident light power is the diffraction efficiency.

[0184] Table 13

[0185]

[0186] As shown in the table above and Figure 1 and Figure 2 As shown, after adding chiral agent / chiral monomer, the photopolymer grating has obvious polarization selectivity, which makes it have wider applications in the fields of light modulation, light display, light blocking and anti-counterfeiting.

[0187] Test Example 2

[0188] The photopolymer grating samples obtained in the above examples and comparative examples were stored in an oven at 55°C, and their diffraction efficiencies obtained by incident polarized light at 0° and 90° were regularly tested. The changes in the obtained diffraction efficiency differences with storage time are shown in Table 14 below:

[0189] Table 14

[0190]

[0191] As shown in the table above and Figure 3 As shown, the stability of the photopolymer grating obtained by adding a chiral monomer is higher than that of the photopolymer grating obtained by adding a chiral agent at a certain temperature. The reason is that the chiral monomer also participates in the polymerization reaction and has a stronger anchoring force on the chiral structure of the polymer.

[0192] Test Example 3

[0193] The haze and transmittance of the photopolymer grating obtained in the above embodiment were measured by a haze meter, and the results are shown in Figure 15 below.

[0194] Table 15

[0195] Haze Transmittance Example 1 7.6％ 75％ Example 2 3.3％ 80％ Example 3 2.2％ 82％ Example 4 1.5％ 84％ Example 5 4.0％ 79％ Example 6 4.8％ 78％ Example 7 3.1％ 80％

[0196] As shown in the table above, since the chiral agent added in Examples 1, 2, 5, 6, and 7 has general miscibility with the system, the final grating haze obtained is large and the light transmittance is poor; while in Examples 3 and 4, chiral monomers are added, and the haze and light transmittance of the chiral monomer system (Examples 3 and 4) are significantly improved compared with the chiral agent system (Examples 1, 2, 5, 6, and 7).

[0197] From the above description, it can be seen that the above-mentioned embodiments of the present invention achieve the following technical effects: by applying the technical scheme of the present application, the chiral photopolymer composition provided by the present application can be polymerized under the induction of polarized light to obtain a chiral polymer, and give the holographic grating a certain polarization selectivity, while improving the uniformity, transmittance and refractive index modulation of the holographic grating, thereby expanding its application in the fields of light modulation, light display, light blocking and anti-counterfeiting.

[0198] In addition, the preparation method of the chiral photopolymer composition induced to form a holographic grating provided in the present application is simple, is conducive to batch production and processing, and has the advantages of good controllability and good stability.

[0199] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A chiral photopolymer composition, characterized in that: The polymer composition comprises the following components by mass percentage: 20-30% of photocurable monomer, 5-20% of chiral compound, 0.6-10% of photoinitiator system, 10-40% of film former, 10-60% of solvent and 0.1-10% of optional additives.

2. The polymer composition according to claim 1, characterized in that The chiral compound is at least one of a chiral agent and / or a chiral monomer, and the chiral agent includes at least one of R5011, S5011, R1011, S1011, R811, S811, CB15, R2011, S2011, CM19, CM20, and CM22.

3. The polymer composition according to claim 2, characterized in that The chiral monomer contains a chiral group, and the chiral monomer has a structure as shown in the following formula (I): Wherein, M represents a chiral group; Q' represents an epoxy group or a (meth)acryloyl group, n represents an integer between 1 and 3; x' represents a direct bond, a substituted or unsubstituted C1-C16 alkylene group, or a substituted or unsubstituted C1-C16 alkyleneoxy group; Y' represents a direct bond, a substituted or unsubstituted aromatic ring, a substituted or unsubstituted cyclohexylene group, a substituted or unsubstituted cyclopentylene group, a methylene group, an oxy group, or a sulfenyl group; and m represents 1 or 2.

4. The polymer composition according to claim 3, characterized in that The M is represented by [Z'(R') p ]*, wherein Z' represents a carbon atom, a carbon-carbon single bond, a carbon-carbon double bond, or a nitrogen-nitrogen double bond; p represents an integer between 1 and 3; R' represents at least one of H, halogen, nitro, hydroxyl, C1-C20 alkyl, C1-C20 alkoxy, C6-C20 aryl, and C5-C20 heteroaryl, and when p>2, each R' is different; Preferably, the R' represents one of the following groups generated by rigid compounds: benzene, naphthalene, benzocyclohexane, fluorene, benzothiophene, azobenzene, cyclohexene, cyclopentene, styrene; Preferably, M represents at least one of the chiral groups generated by the following chiral substances: L / D-leucine, L / D-lysine, L / D-glutamic acid, L / D-alanine, L / D-benzoic acid, S-2-methyl-1-butanol, γ-substituted-γ-butyrolactone, δ-substituted-δ-valerolactone, azobenzene, binaphthyl, diarylethene, vinyl dicyclohexane, aryl vinyl nitrile; More preferably, the chiral monomer is selected from at least one of 4-acryloylundecanyloxy-4'-(S(-)-2-methylbutyloxy)-binaphthyl and 4-acryloyloxybenzoyloxycholesteryl acetate.

5. The polymer composition according to claim 1, characterized in that The photocurable monomer has a structure shown in the following formula (II): (Q) q -X-A-Y-B-Z Formula (II) Wherein, Q represents an epoxy group or a (meth)acryloyl group, q represents an integer between 1 and 3; X represents a direct bond, a substituted or unsubstituted C1-C16 alkylene group, or a substituted or unsubstituted C1-C16 alkyleneoxy group; Y represents a direct bond, a substituted or unsubstituted arylene group, a para-aryldi(acyl)oxy group, *CH2*, *C(CH3)2*, *CH2-CH2*, *CH=CH*, *C≡C*, *CH=N*, *N=N*, *N(O)*; A and B each independently represent a substituted or unsubstituted arylene group, or a substituted or unsubstituted cyclohexylene group; Z represents H, halogen, amino, cyano, isocyano, amino, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C1-C20 alkoxy group, a C1-C20 ester group, or a substituted or unsubstituted C1-C20 ether group; Preferably, the photocurable monomer is selected from at least one of RM257, RM82 or 2,2-bis(4-epoxypropoxyphenyl)propane.

6. The polymer composition according to claim 1, characterized in that The photoinitiator system comprises a photoinitiator and a co-initiator, and the mass ratio of the two is (0.1-5):(0.5-5); Preferably, the initiator comprises at least one of Irgacure 784, Basic Red 2, Dioscorea Red Y, Methylene Blue, Rhodamine 6G, Diiodofluorescein, Aminocoumarin, Tetraphenylborate, Triphenyl-n-butylborate, 2-isopropylthioxanthone, and ethyl 4-dimethylaminobenzoate; Preferably, the co-initiator includes at least one of triethanolamine, methyldiethanolamine, butyldiethanolamine, N-phenylglycine, and 2-(4-chlorophenyl)-4,5-diphenylimidazole.

7. The polymer composition according to claim 1, characterized in that The film-forming agent is a polymer, the number average molecular weight of the polymer is 1000 to 200000, and the refractive index of the film-forming agent is preferably ≤1.480; Preferably, the film-forming agent includes at least one of cellulose ester, cellulose ether, polyvinyl alcohol, polyvinyl acetal, polyurethane, styrene-butadiene copolymer, polyvinyl pyrrolidone, vinyl acetate homopolymer, vinyl acetate-acrylate copolymer, vinyl acetate-ethylene copolymer, and vinyl acetate-styrene copolymer.

8. The polymer composition according to any one of claims 1 to 7, characterized in that The solvent is a non-reactive solvent, preferably at least one of a halogenated hydrocarbon solvent, a ketone solvent, an alcohol solvent, an ester solvent, a hydrocarbon solvent, and an amide solvent; And / or, the additive includes at least one of a dye, a polar solvent, a plasticizer, a toughening agent, an inhibitor, a light stabilizer, a chain transfer agent, a leveling agent, a wetting agent, a defoaming agent, a tackifier, an oligomer, a compound having a hydrophilic group, and an oxygen-containing compound.

9. A holographic grating, characterized in that: The holographic grating comprises a polymer film having a grating structure, and the material of the polymer film is the chiral photopolymer composition according to any one of claims 1 to 8; Preferably, the method for preparing the polymer film comprises the following steps: Step S1, mixing the photocurable monomer, the chiral compound, the photoinitiator system, the film-forming agent, the solvent and the optional additives to obtain a mixture; Step S2, preparing the mixture into a film to be cured; Step S3, forming a grating structure on at least a portion of the film to be solidified to obtain the polymer film having the grating structure; Preferably, step S3 includes the step of performing exposure using coherent light.

10. A holographic device, characterized in that: The holographic device comprises the holographic grating as claimed in claim 9.

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