Photopolymer holographic recording material containing a mercapto compound, an acrylate compound and an epoxy compound and optical grating

Abstract

The application provides a photopolymer holographic recording material containing a mercapto compound, an acrylate compound and an epoxy compound, and comprises: 10-50 parts by weight of a polymerization monomer; 10-40 parts by weight of a film forming agent; 0.1-5 parts by weight of a photoinitiator; and 0.5-5 parts by weight of a co-initiator; wherein the polymerization monomer comprises a mercapto compound, an epoxy compound and an acrylate compound. Compared with the prior art, the application introduces sulfur element into the photopolymer monomer to increase the refractive index of the monomer, effectively increases the refractive index of the bright area through the light-induced mercapto-epoxy / mercapto-acrylate hybrid polymerization, further increases the refractive index difference between the monomer and the film forming agent, and thus increases the refractive index modulation degree of the photopolymer. Meanwhile, as a typical 'click chemistry' reaction, the polymerization reaction has the advantages of mild reaction condition, small amount of photoinitiator, small volume shrinkage, no oxygen inhibition, excellent thermal and mechanical properties and the like.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of optical materials, and particularly relates to a photopolymer holographic recording material containing a mercapto compound, an acrylate compound and an epoxy compound and an optical grating. BACKGROUND

[0002] Holographic recording material is a kind of material that can record all information (including amplitude and phase) of object light wave in the form of interference fringes by the principle of optical interference. In a typical processing mode, a photopolymer composition forms a component by visible light laser irradiation, and monomers in the photopolymer composition used for holographic recording form (cured) polymers through a polymerization reaction. As a result, a structural feature capable of forming an interference pattern can be generated in the component formed by the photopolymer composition. At the same time, by modulating the refractive index, a phase hologram with high diffraction efficiency can be formed. The photosensitive / photopolymer material has the characteristics of high sensitivity, high resolution, high signal-to-noise ratio, low cost, simple processing technology, etc., and is one of the most potential recording materials in the field of volume holographic devices.

[0003] The photosensitive / photopolymer system as a holographic recording material generally contains dyes, photoinitiators, one or more monomers, film formers, etc. After recording light irradiates the polymer, the dye is excited by photons, and then interacts with the initiator to produce free radicals or ions to initiate the polymerization of monomer molecules. Among them, the monomers in the exposed area are polymerized and the concentration is reduced, forming a monomer concentration gradient with the dark area, so that the monomers in the dark area diffuse to the bright area and the polymer is enriched in the bright area. Finally, through the fixing process of uniform exposure, the residual monomers are completely polymerized, and finally a phase-type hologram is formed in the medium. Therefore, theoretically, the greater the difference between the refractive index of the monomer and the film former, the greater the refractive index modulation of the final photopolymer grating.

[0004] At present, DuPont Company (such as US patents with patent numbers US5013632, US5098803, US4950567, US4959284, US4987230, US4994347, US5292620, US5402514), Polyvision Company, Canon Company, Fuji Company and Covestro Company (Chinese patents with publication numbers CN107223121A, CN102667934B, CN102667936B) have all launched their own developed photosensitive / photopolymer holographic recording materials, but most of the products have the problems of not high enough refractive index modulation and not large enough angle selectivity, which is difficult to meet the market requirements for wide FOV imaging system. Therefore, developing monomers with higher refractive index, improving the refractive index modulation and the diffraction efficiency are one of the main research and development directions of the photopolymer material at present.

[0005] According to the Lorentz-Lorenz relation, the refractive index of a material is related to the molar volume of the material and the molar refractivity of the material itself, as shown below:

[0006]

[0007] In the formula, n represents the refractive index of the material, [R] represents the molar refractivity of the molecule, and V0 represents the molar volume. As can be seen from the above formula, if the material has a larger molar refractivity or a smaller molar volume, a higher refractive index can be obtained. For example, introducing aromatic rings, halogen atoms other than fluorine, sulfur atoms, heavy metals, etc. into the molecular structure can effectively increase the refractive index of the material. However, the molar dispersion of aromatic rings is large, and excessive introduction will affect the optical performance of the polymer when used as an optical material; at the same time, the introduction of aromatic rings, bromine atoms and heavy metal elements will also reduce the solubility of the material; and the stability of iodine is not good, and the introduction of iodine will reduce the light and thermal stability of the material. SUMMARY

[0008] Therefore, the technical problem to be solved by the present application is to provide a photopolymer holographic recording material containing a mercapto compound, an acrylate compound and an epoxy compound, which has high area selectivity and a high refractive index modulation degree.

[0009] The present application provides a photopolymer holographic recording material containing a mercapto compound, an acrylate compound and an epoxy compound, comprising:

[0010]

[0011] The polymerized monomers include a mercapto compound, an epoxy compound and an acrylate compound;

[0012] The mass ratio of the mercapto compound, the epoxy compound and the acrylate compound is (1-3):(0.5-2):(1-2).

[0013] Preferably, the mercapto compound is as shown in formula (I):

[0014]

[0015] wherein X is an alkane group lacking a H, a thioether-containing group, an ether bond-containing group, an aromatic hydrocarbon group, a cycloalkane group or a heterocyclic group;

[0016] Y is one of an alkylene group, an arylene group, S, O and an alkylidene group, or a group formed by connecting two or more of the above groups by a single bond;

[0017] When the atom in X connected to Y is S or O, a is 1 or 2;

[0018] when the atom in X which is connected to Y is C, a is an integer from 1 to 4;

[0019] n is an integer from 0 to 4.

[0020] Preferably, X is CR 4-a , SR' 2-a , OR" 2-a , a C6-C20 aromatic hydrocarbon group lacking a H, a C3-C20 cycloalkane group lacking a H or a C2-C20 heterocyclic group lacking a H; R, R' and R" are each independently H, an alkyl group or an aryl group;

[0021] Y is one of a C1-C4 alkylene group, a C6-C12 arylene group, S, O and a C2-C5 alkylene ester group or a group formed by two or more of the above groups being connected by a single bond.

[0022] Preferably, the mercapto compound is selected from one or more of compounds 1 to 7:

[0023]

[0024] Preferably, the epoxy compound is as shown in formula (II):

[0025]

[0026] Q and Q' are each independently selected from a group containing an epoxy structure;

[0027] Z is a heteroatom, a single bond, a substituted or unsubstituted alkylene group; the substituent in the substituted alkylene group is selected from one or both of a C6-C30 aryl group, a C1-C10 alkyl group and a C1-C10 alkoxy group or the above groups are bonded by a single bond;

[0028] E and E' are each independently selected from a heteroatom;

[0029] Ar and Ar' are each independently selected from a group containing an aryl group;

[0030] or Ar and Ar' are connected by a substituent;

[0031] m and m' are each independently an integer from 0 to 3, and are not simultaneously 0;

[0032] when m is 0, E is a C1-C10 alkyl group;

[0033] when m' is 0, E' is a C1-C10 alkyl group;

[0034] the acrylate compound is as shown in formula (III):

[0035]

[0036] each of Q1and Q1' is independently selected from a group containing an acryloyl structure or a group containing a methacryloyl structure;

[0037] Z1is a heteroatom, a single bond, a substituted or unsubstituted alkylene group; the substituent in the substituted alkylene group is selected from one or both of a C6-C30 aryl group, a C1-C10 alkyl group and a C1-C10 alkoxy group or the above groups are bonded by a single bond;

[0038] each of E1and E1' is independently selected from a heteroatom;

[0039] each of Ar1and Ar1' is independently selected from a group containing an aryl group;

[0040] or Ar1and Ar1' are connected by a substituent;

[0041] each of m1and m1' is independently an integer of 0 to 3, and is not simultaneously 0;

[0042] when m1is 0, E1is a C1-C10 alkyl group;

[0043] when m1' is 0, E1' is a C1-C10 alkyl group.

[0044] Preferably, the group containing an epoxy structure is a C2-C10 aliphatic group containing an epoxy structure or a C5-C20 alicyclic group containing an epoxy structure;

[0045] the group containing an acryloyl structure is an acryloyl group or a C5-C15 aliphatic group containing an acryloyl structure;

[0046] the group containing a methacryloyl structure is a methacryloyl group or a C5-C15 aliphatic group containing a methacryloyl structure;

[0047] Z is oxygen, nitrogen, sulfur, silicon, a single bond, a substituted or unsubstituted C1-C10 alkylene group; the substituent in the substituted alkylene group is selected from one or both of a C6-C20 aryl group, a C1-C5 alkyl group and a C1-C5 alkoxy group or the above groups are bonded by a single bond;

[0048] each of E and E' is independently selected from oxygen, nitrogen, sulfur or silicon;

[0049] each of Ar and Ar' is independently selected from a group containing a benzene ring;

[0050] or Ar and Ar' are each independently selected from a group comprising a benzene ring and the benzene ring is connected by a substituted methylene; the substituent in the substituted methylene is a C1-C5 alkylene; E is connected to Ar through the substituent on the substituted methylene, and E' is connected to Ar' through the substituent on the substituted methylene;

[0051] Z1 is oxygen, nitrogen, sulfur, silicon, a single bond, substituted or unsubstituted C1-C10 alkylene; the substituent in the substituted alkylene is selected from one or both of C6-C20 aryl, C1-C5 alkyl and C1-C5 alkoxy, or the above groups are bonded by a single bond;

[0052] E1 and E1' are each independently selected from oxygen, nitrogen, sulfur or silicon;

[0053] Ar1 and Ar1' are each independently selected from a group comprising a benzene ring;

[0054] or Ar1 and Ar1' are each independently selected from a group comprising a benzene ring and the benzene ring is connected by a substituted methylene; the substituent in the substituted methylene is a C1-C5 alkylene; E1 is connected to Ar1 through the substituent on the substituted methylene, and E1' is connected to Ar1' through the substituent on the substituted methylene.

[0055] Preferably, the group comprising an epoxy structure is a C2-C4 aliphatic group comprising an epoxy structure or a C5-C10 alicyclic group comprising an epoxy structure; the epoxy structure is selected from an oxirane group, an oxetane group or a butylene oxide group;

[0056] the group comprising an acryloyl structure is an acryloyl group or a C5-C10 aliphatic group comprising an acryloyl structure;

[0057] the group comprising a methacryloyl structure is a methacryloyl group or a C5-C10 aliphatic group comprising a methacryloyl structure;

[0058] Z is oxygen, sulfur, a single bond, substituted or unsubstituted C1-C5 alkylene; the substituent in the substituted alkylene is selected from one or both of C6-C10 aryl, C1-C3 alkyl and C1-C3 alkoxy, or the above groups are bonded by a single bond;

[0059] E and E' are each independently selected from oxygen or sulfur;

[0060] Ar and Ar' are each independently selected from a group represented by formula (a) or formula (b):

[0061]

[0062] L is a single bond, oxygen or sulfur;

[0063] or Ar and Ar' are each independently selected from a group represented by formula (a) or formula (b) and are connected by a substituted methylene; the substituent of the substituted methylene is C1-C3 alkylene; E is connected to Ar by the substituent of the substituted methylene, and E' is connected to Ar' by the substituent of the substituted methylene;

[0064] Z1 is oxygen, sulfur, a single bond, substituted or unsubstituted C1-C5 alkylene; the substituent of the substituted alkylene is selected from one or both of C6-C10 aryl, C1-C3 alkyl and C1-C3 alkoxy, or the above groups are bonded by a single bond;

[0065] E1 and E1' are each independently selected from oxygen or sulfur;

[0066] Ar1 and Ar1' are each independently selected from a group represented by formula (a) or formula (b);

[0067] or Ar1 and Ar1' are each independently selected from a group represented by formula (a) or formula (b) and are connected by a substituted methylene; the substituent of the substituted methylene is C1-C3 alkylene; E1 is connected to Ar1 by the substituent of the substituted methylene, and E1' is connected to Ar1' by the substituent of the substituted methylene.

[0068] Preferably, the epoxy compound is a polyphenol type glycidyl epoxy monomer; the acrylate compound is 9,9-bis(methyl acrylate) fluorene.

[0069] Preferably, 10-50 parts by weight of a solvent and 0.1-5 parts by weight of other additives are further included;

[0070] The film-forming agent is selected from one or more of a polymer comprising vinyl acetate monomer units, a cellulose ester, a cellulose ether, a polyvinyl alcohol, a polyvinyl acetal, a polyurethane, a block copolymer comprising styrene monomer units and / or butadiene monomer units, and a polyvinyl pyrrolidone;

[0071] The photoinitiator is selected from a free radical type photoinitiator and / or a photobase generator;

[0072] The radical photoinitiator is selected from one or more of Irgacure 784, neomethylene blue, thionine, basic red 2, basic yellow, pinacyl chloride, rhodamine 6G, malachite green, ethyl violet, Victoria blue R, lapis lazuli blue, quinaldine red, brilliant green, basic orange G, darrow red, pyronine Y, rose Bengal, eosin Y, Michler's ketone, aminocoumarin, pyrylium iodine, diiodofluorescein, anthocyanin, methylene blue, 2,5-bis{[4-(diethylamino)-2-methylphenyl]methylene}cyclopentanone, azure A, crystal violet and malachite green;

[0073] The photobase generator is selected from one or more of a carbamate photobase generator, an aminoketone photobase generator, a benzoylformamide photobase generator, a cobalamin complex photobase generator, a quaternary ammonium salt photobase generator, a tetraphenylborate salt photobase generator and a carboxylate salt photobase generator;

[0074] The co-initiator is selected from one or more of ethylenediamine, triethanolamine, N-methyldiethanolamine, N-butyldiethanolamine, N-phenylglycine, 2-(4-chlorophenyl)-4,5-diphenylimidazole and 4-dimethyl-aminobenzoic acid ethyl ester.

[0075] The present application also provides a grating, which is a resin film having a grating structure; the resin film is formed of the above-mentioned photopolymer holographic recording material containing a mercapto compound, an acrylate compound and an epoxy compound.

[0076] The present application provides a photopolymer holographic recording material containing a mercapto compound, an acrylate compound and an epoxy compound, comprising: 10-50 parts by weight of a polymerized monomer; 10-40 parts by weight of a film-forming agent; 0.1-5 parts by weight of a photoinitiator; and 0.5-5 parts by weight of a co-initiator; the polymerized monomer comprises a mercapto compound, an epoxy compound and an acrylate compound; the mass ratio of the mercapto compound, the epoxy compound and the acrylate compound is (1-3):(0.5-2):(1-2). Compared with the prior art, the present application introduces sulfur element into the photopolymer monomer to improve the refractive index of the monomer, includes a mercapto monomer with high refractive index, effectively improves the refractive index of the bright area through the light-induced mercapto-epoxy / mercapto-acrylate hybrid polymerization, further improves the refractive index difference between the monomer and the film-forming agent, and thus improves the refractive index modulation degree of the photopolymer. Meanwhile, as a typical "click chemistry" reaction, such a polymerization reaction also has the advantages of mild reaction conditions, small amount of photoinitiator, small volume shrinkage, no oxygen inhibition, excellent thermal performance and mechanical performance, etc. BRIEF DESCRIPTION OF DRAWINGS

[0077] Figure 1 A structural schematic diagram of a grating element provided by the present application is shown in the figure;

[0078] Figure 2Exposure light path schematic diagram for preparing the grating of the present application;

[0079] Figure 3 Diffractive efficiency curve diagram of the reflective holographic grating obtained in the embodiment 1 and 2 and the comparative example 1 and 2 of the present application;

[0080] Figure 4 Transmittance curve diagram of the reflective holographic grating obtained in the embodiment 1 of the present application after heat treatment at different temperatures;

[0081] Figure 5 Transmittance curve diagram of the reflective holographic grating obtained in the embodiment 2 of the present application after heat treatment at different temperatures;

[0082] Figure 6 Transmittance curve diagram of the reflective holographic grating obtained in the comparative example 1 of the present application after heat treatment at different temperatures;

[0083] Figure 7 Transmittance curve diagram of the reflective holographic grating obtained in the comparative example 2 of the present application after heat treatment at different temperatures. DETAILED DESCRIPTION

[0084] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0085] The present application provides a photopolymer holographic recording material containing a mercapto compound, an acrylate compound and an epoxy compound, comprising:

[0086]

[0087] The polymerized monomer comprises a mercapto compound, an epoxy compound and an acrylate compound;

[0088] The mass ratio of the mercapto compound, the epoxy compound and the acrylate compound is (1-3):(0.5-2):(1-2).

[0089] In the present application, there is no special limitation on the source of all raw materials, which can be commercially available.

[0090] In the photopolymer holographic recording material provided by the present application, the content of the polymerized monomer is preferably 20-50 parts by weight, more preferably 25-50 parts by weight, more preferably 30-50 parts by weight, more preferably 35-50 parts by weight, and most preferably 40-45 parts by weight.

[0091] During exposure, polymerizable monomers undergo polymerization and form cross-linked structures. In this invention, the polymerizable monomers include thiol compounds, epoxy compounds, and acrylate compounds. Under light irradiation, a photo-alkali-generating agent produces a strong base to initiate thiol-epoxy polymerization, and a photosensitizer produces free radicals to initiate thiol-acrylate polymerization, thereby achieving photo-initiated thiol-epoxy / thiol-acrylate hybrid polymerization. The mass ratio of the thiol compound, epoxy compound, and acrylate compound is (1-3):(0.5-2):(1-2), preferably (1.5-2.5):(0.5-1.5):(1-2), more preferably (1.8-2.2):(0.8-1.2):(1.2-1.8), and even more preferably 2:1:1.5.

[0092] In this invention, the thiol compound preferably has a refractive index of 1.53 or higher, more preferably 1.55 or higher, and even more preferably 1.57 or higher. Further preferably, the thiol compound is as shown in formula (I), and to increase the monomer refractive index, sulfur atoms and aryl groups can be introduced into X and Y as much as possible:

[0093]

[0094] Wherein, X is an alkane group lacking a H, a sulfide-containing group, an ether-containing group, an aromatic group, a cycloalkane group, or a heterocyclic group; preferably CR 4-a ,SR' 2-a OR 2-a The following are preferred: a C6-C20 aromatic group lacking a H atom, a C3-C20 cycloalkane group lacking a H atom, or a C2-C20 heterocyclic group lacking a H atom; more preferably, CR 4-a ,SR' 2-a OR 2-a The following are preferred: A C6-C16 aromatic group lacking *a* H atoms; a C3-C16 cycloalkane group lacking *a* H atoms; or a C2-C16 heterocyclic group lacking *a* H atoms. 4-a ,SR' 2-a OR 2-a The following are preferred: A C6-C12 aromatic group lacking *a* H atoms; a C3-C12 cycloalkane group lacking *a* H atoms; or a C2-C12 heterocyclic group lacking *a* H atoms. 4-a ,SR' 2-a OR 2-a The following are preferred: A C6-C12 aromatic group lacking *a* H atoms; a C3-C8 cycloalkane group lacking *a* H atoms; or a C2-C8 heterocyclic group lacking *a* H atoms. 4-a ,SR' 2-a OR2-a , a C6-C12 aromatic hydrocarbon group formed by lacking a H, a C3-C6 cycloalkane group formed by lacking a H, or a C2-C6 heterocyclic group formed by lacking a H, most preferably CR 4-a , SR' 2-a , OR" 2-a , a phenyl group formed by lacking a H, a biphenyl group formed by lacking a H, a cyclopropyl group formed by lacking a H, a cyclobutyl group formed by lacking a H, a cyclopentyl group formed by lacking a H, a cyclohexyl group formed by lacking a H, a three-membered heterocyclic group formed by lacking a H, a four-membered heterocyclic group formed by lacking a H, a five-membered heterocyclic group formed by lacking a H, or a six-membered heterocyclic group formed by lacking a H; the heteroatoms in the heterocyclic group are preferably S and / or O; the number of heteroatoms in the heterocyclic group is preferably 1-3; R, R', and R" are each independently H, an alkyl group, or an aryl group, preferably H, a C1-C10 alkyl group, or a C6-C20 aryl group, more preferably H, a C1-C6 alkyl group, or a C6-C16 aryl group, further preferably H, a C1-C4 alkyl group, or a C6-C12 aryl group, most preferably H, a C1-C2 alkyl group, or a C6-C10 aryl group; the aryl group can be unsubstituted or substituted, and is not particularly limited.

[0095] Y is one of an alkylene group, an arylene group, S, O, and an alkylene ester group, or a group formed by two or more of the above groups being connected by a single bond; preferably one of a C1-C10 alkylene group, a C6-C20 arylene group, S, O, and a C2-C10 alkylene ester group, or a group formed by two or more of the above groups being connected by a single bond; more preferably one of a C1-C6 alkylene group, a C6-C16 arylene group, S, O, and a C2-C6 alkylene ester group, or a group formed by two or more of the above groups being connected by a single bond; further preferably one of a C1-C4 alkylene group, a C6-C12 arylene group, S, O, and a C2-C5 alkylene ester group, or a group formed by two or more of the above groups being connected by a single bond; further preferably one of a C1-C3 alkylene group, a C6-C10 arylene group, S, O, and a C2-C4 alkylene ester group, or a group formed by two or more of the above groups being connected by a single bond; most preferably one of a C1-C2 alkylene group, a C6 arylene group, S, O, and a C2-C3 alkylene ester group, or a group formed by two or more of the above groups being connected by a single bond.

[0096] When the atom in X that is connected to Y is S or O, a is 1 or 2;

[0097] When the atom in X to which Y is attached is C, a is an integer of 1 to 4, more preferably an integer of 2 to 4; when a is an integer of 2 or more, a groups can be attached to the same C atom in X or to different C atoms in X, and there is no particular limitation.

[0098] n is an integer of 0 to 4, preferably an integer of 0 to 3, more preferably an integer of 0 to 2, still more preferably 0 or 1.

[0099] Further preferably, the mercapto compound is one or more of compounds 1 to 7:

[0100]

[0101]

[0102] The epoxy compound preferably has a refractive index of 1.57 or more, more preferably 1.58 or more, still more preferably 1.60 or more. Further preferably, the epoxy compound is represented by formula (II):

[0103]

[0104] Q and Q' are each independently selected from a group containing an epoxy structure; preferably a C2 to C10 aliphatic group containing an epoxy structure or a C5 to C20 alicyclic group containing an epoxy structure; more preferably a C2 to C6 aliphatic group containing an epoxy structure or a C5 to C16 alicyclic group containing an epoxy structure; still more preferably a C2 to C4 aliphatic group containing an epoxy structure or a C5 to C10 alicyclic group containing an epoxy structure; the epoxy structure is preferably located at a terminal group; the epoxy structure is preferably an oxirane group, an oxetane group, or a butylene oxide group.

[0105] Z is a heteroatom, a single bond, a substituted or unsubstituted alkylene group, preferably a heteroatom, a single bond, a substituted or unsubstituted C1-C10 alkylene group, more preferably a heteroatom, a single bond, a substituted or unsubstituted C1-C5 alkylene group; when Z is a heteroatom, it is preferably selected from an oxygen atom or a sulfur atom from the viewpoint of suppressing dimensional shrinkage after film formation and improving the light transmittance, haze, and diffraction efficiency of the resulting grating; thus, Z is further preferably an oxygen atom, a sulfur atom, a single bond, a substituted or unsubstituted C1-C5 alkylene group, more preferably an oxygen atom, a sulfur atom, a single bond, a substituted or unsubstituted C1-C3 alkylene group, and most preferably an oxygen atom, a sulfur atom, a single bond, a substituted or unsubstituted C1-C2 alkylene group; the substituent in the substituted alkylene group is preferably one or both of a C6-C30 aryl group, a C1-C10 alkyl group, and a C1-C10 alkoxy group, or the above groups bonded via a single bond, more preferably one or both of a C6-C20 aryl group, a C1-C5 alkyl group, and a C1-C5 alkoxy group, or the above groups bonded via a single bond, and more preferably one or both of a C6-C10 aryl group, a C1-C3 alkyl group, and a C1-C3 alkoxy group, or the above groups bonded via a single bond, and most preferably one or both of a C6 aryl group, a C1-C2 alkyl group, and a C1-C2 alkoxy group, or the above groups bonded via a single bond.

[0106] E and E' are each independently a heteroatom, preferably an oxygen atom, a nitrogen atom, a sulfur atom, or a silicon atom, and more preferably an oxygen atom or a sulfur atom from the viewpoint of suppressing dimensional shrinkage after film formation and improving the light transmittance, haze, and diffraction efficiency of the resulting grating.

[0107] Ar and Ar' are each independently a group containing an aryl group, and preferably a group containing a benzene ring from the viewpoint of improving the light transmittance, haze, dimensional stability, and refractive index of the resulting grating, and more preferably a group represented by formula (a) or formula (b):

[0108]

[0109] L is a single bond, an oxygen atom, or a sulfur atom.

[0110] or Ar and Ar' are connected via a substituent, preferably a group containing a benzene ring and the benzene rings are connected via a substituted methylene group, and more preferably a group represented by formula (a) or formula (b) and the two groups are connected via a substituted methylene group; the substituent in the substituted methylene group is preferably a C1-C5 alkylene group, more preferably a C1-C3 alkylene group, and more preferably a C1-C2 alkylene group; E is connected to Ar via the substituent on the substituted methylene group, and E' is connected to Ar' via the substituent on the substituted methylene group.

[0111] m and m' are each independently an integer of 0 to 3, and are not simultaneously 0, preferably 1 or 2; when m is 0, E is a C1-C10 alkyl group, preferably a C1-C5 alkyl group, more preferably a C1-C3 alkyl group, still more preferably a C1-C2 alkyl group; when m' is 0, E' is a C1-C10 alkyl group, preferably a C1-C5 alkyl group, more preferably a C1-C3 alkyl group, still more preferably a C1-C2 alkyl group.

[0112] In the embodiments provided in the present application, the epoxy compound is specifically a polyphenol type glycidyl epoxy monomer, and more specifically one or more of bisphenol A diglycidyl ether, bisphenol A propoxylated diglycidyl ether, and 9,9-bis(4- glycidyloxyphenyl)fluorene.

[0113] In the present application, the acrylate compound preferably has a refractive index of 1.57 or more, more preferably 1.58 or more, and further preferably 1.60 or more; preferably, the acrylate compound is represented by formula (III):

[0114]

[0115] Q1and Q1' are each independently a group containing an acryloyl structure or a group containing a methacryloyl structure; the group containing an acryloyl structure is preferably an acryloyl group or a C4-C15 aliphatic group containing an acryloyl structure, more preferably an acryloyl group or a C4-C10 aliphatic group containing an acryloyl structure, still more preferably an acryloyl group or a C4-C8 aliphatic group containing an acryloyl structure, and most preferably an acryloyl group or a C4-C6 aliphatic group containing an acryloyl structure; the group containing a methacryloyl structure is preferably a methacryloyl group or a C5-C15 aliphatic group containing a methacryloyl structure, more preferably a methacryloyl group or a C5-C10 aliphatic group containing a methacryloyl structure, still more preferably a methacryloyl group or a C5-C8 aliphatic group containing a methacryloyl structure, and most preferably a methacryloyl group or a C5-C6 aliphatic group containing a methacryloyl structure.

[0116] Z1is a heteroatom, a single bond, a substituted or unsubstituted alkylene group, preferably an oxygen, a nitrogen, a sulfur, a silicon, a single bond, a substituted or unsubstituted C1-C10 alkylene group, more preferably an oxygen, a nitrogen, a sulfur, a silicon, a single bond, a substituted or unsubstituted C1-C5 alkylene group; when Z1is a heteroatom, from the viewpoint of suppressing dimensional shrinkage after film formation and improving the light transmittance, haze, and diffraction efficiency of the resulting grating, the heteroatom is preferably an oxygen atom or a sulfur atom; thus, Z1is further preferably an oxygen, a sulfur, a single bond, a substituted or unsubstituted C1-C5 alkylene group, more preferably an oxygen, a sulfur, a single bond, a substituted or unsubstituted C1-C3 alkylene group, and most preferably an oxygen, a sulfur, a single bond, a substituted or unsubstituted C1-C2 alkylene group; the substituent in the substituted alkylene group is preferably one or both of a C6-C30 aryl group, a C1-C10 alkyl group, and a C1-C10 alkoxy group, or the above groups bonded via a single bond, more preferably one or both of a C6-C20 aryl group, a C1-C5 alkyl group, and a C1-C5 alkoxy group, or the above groups bonded via a single bond, and more preferably one or both of a C6-C10 aryl group, a C1-C3 alkyl group, and a C1-C3 alkoxy group, or the above groups bonded via a single bond, and most preferably one or both of a C6 aryl group, a C1-C2 alkyl group, and a C1-C2 alkoxy group, or the above groups bonded via a single bond.

[0117] E1and E1' are each independently a heteroatom, preferably an oxygen, a nitrogen, a sulfur, or a silicon; from the viewpoint of suppressing dimensional shrinkage after film formation and improving the light transmittance, haze, and diffraction efficiency of the resulting grating, more preferably an oxygen or a sulfur.

[0118] Ar1and Ar1' are each independently a group containing an aryl group, from the viewpoint of improving the light transmittance, haze, dimensional stability, and refractive index of the resulting grating, preferably a group containing a benzene ring, and more preferably a group represented by formula (a) or formula (b):

[0119]

[0120] L is a single bond, an oxygen, or a sulfur.

[0121] or Ar1and Ar1' are connected via a substituent, preferably a group containing a benzene ring and the benzene rings are connected via a substituted methylene group, and more preferably a group represented by formula (a) or formula (b) and the two are connected via a substituted methylene group; the substituent in the substituted methylene group is preferably a C1-C5 alkylene group, more preferably a C1-C3 alkylene group, and more preferably a C1-C2 alkylene group; E1is connected to Ar1via the substituent on the substituted methylene group, and E1' is connected to Ar' via the substituent on the substituted methylene group.

[0122] m1and m1' are each independently an integer from 0 to 3, and are not simultaneously 0, preferably 1 or 2; when m1is 0, E1is a C1-C10 alkyl group, preferably a C1-C5 alkyl group, more preferably a C1-C3 alkyl group, and even more preferably a C1-C2 alkyl group; when m1' is 0, E1' is a C1-C10 alkyl group, preferably a C1-C5 alkyl group, more preferably a C1-C3 alkyl group, and even more preferably a C1-C2 alkyl group.

[0123] In the embodiments provided by the present application, the acrylate compound is specifically one or more of ethoxylated bisphenol A diacrylate, ethoxylated bisphenol A dimethacrylate, 9,9-bis(methyl acrylate) fluorene, and bisphenol A glyceride.

[0124] In addition to the above-mentioned acrylate compound or epoxy compound having a high refractive index, other types or structures of acrylate or epoxy monomers, including mono- and polyfunctional acrylate monomers, mono- and polyfunctional epoxy monomers, and mono- and polyfunctional epoxy acrylate monomers, can be used without affecting the technical effects of the present application, specifically: other acrylate monomers that can be used include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, ethoxyethyl acrylate, ethoxyethyl methacrylate, n-butyl acrylate, n-butyl methacrylate, t-butyl acrylate, t-butyl methacrylate, hexyl acrylate, hexyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, butoxyethyl acrylate, butoxyethyl methacrylate, dodecyl acrylate, dodecyl methacrylate, isobornyl acrylate, isobornyl methacrylate, phenyl acrylate, N-carbazolyl acrylate, 2-phenylthioethyl acrylate, 2-phenoxyethyl acrylate, 2-naphthoxyethyl acrylate, and the like. Other epoxy monomers that can be used include polyphenol-type glycidyl ether epoxy monomers, aliphatic glycidyl ether epoxy monomers, glycidyl ester epoxy monomers, glycidyl amine epoxy monomers, heterocyclic epoxy monomers, epoxy acrylate monomers, and the like.

[0125] In addition, other polymerizable monomers having other structures can be contained in the monomer component of the present application having the above-mentioned structure, in addition to the polymerizable monomers necessary for the monomer component of the present application, without affecting the technical effects of the present application. These other polymerizable monomers can generally be selected from other olefinic or acetylenic monomers. In some specific embodiments of the present application, it is considered advantageous to add an acetylenic monomer having a high refractive index, because the reaction ratio of acetylenic monomers with mercapto groups during radical photocuring is 1:2, i.e., one triple bond can react with two mercapto groups, which is advantageous for introducing more sulfur elements and further increasing the refractive index.

[0126] In the photopolymer holographic recording material provided by the present application, the content of the film-forming agent is preferably 15-40 parts by weight, more preferably 15-35 parts by weight, even more preferably 20-30 parts by weight, and most preferably 20-25 parts by weight; in the examples provided by the present application, the content of the film-forming agent is specifically 20 parts by weight; in the present application, the film-forming agent is preferably a polymer and / or a resin material with a molecular weight of 1000 or more and a certain adhesion. More preferably, the film-forming agent is a polymer and / or a resin material with a relatively low refractive index, and in some specific embodiments, the refractive index of these materials is 1.480 or less; even more preferably, the film-forming agent is one or more of a polymer containing vinyl acetate monomer units, a cellulose ester, a cellulose ether, a polyvinyl alcohol, a polyvinyl acetal, a polyurethane, a block copolymer containing styrene monomer units and / or butadiene monomer units, and polyvinylpyrrolidone; wherein the polymer containing vinyl acetate monomer units is preferably a homopolymer of vinyl acetate and / or a copolymer of vinyl acetate and one or more of acrylate, ethylene, styrene, etc.; the cellulose ester is preferably one or more of cellulose acetate, cellulose acetate-succinate, and cellulose acetate-butyrate; the cellulose ether is preferably one or more of methyl cellulose, ethyl cellulose, and benzyl cellulose; the polyvinyl acetal is preferably polyvinyl butyral and / or polyvinyl formal; the polyurethane is generally obtained by the reaction of a polyol and an isocyanate, wherein the polyol is, for example, polytetrahydrofuran, polyethylene glycol, polypropylene glycol, castor oil, and the isocyanate is, for example, hexamethylene-1,6-diisocyanate, 1,4-cyclohexane diisocyanate, and methyl-2,4-diisocyanate. From the perspective of inhibiting the dimensional shrinkage of the final grating product and improving the diffraction efficiency, the film-forming agent of the present application is most preferably at least one of cellulose acetate-butyrate, polyvinylpyrrolidone, polyvinyl alcohol, and polyvinyl acetate.

[0127] In the photopolymer holographic recording material provided by the present application, the photoinitiator system comprises a photoinitiator and a co-initiator. The content of the photoinitiator is preferably 0.5-4 parts by weight, more preferably 0.5-3 parts by weight, and even more preferably 1-2 parts by weight; the content of the co-initiator is preferably 0.5-4 parts by weight, more preferably 1-3 parts by weight, and even more preferably 1-2 parts by weight.

[0128] The photoinitiator is a photosensitive compound capable of absorbing light of a specific wavelength and generating active species having the ability to initiate polymerization through a series of chemical processes. According to the type of active center generated after photolysis, the photoinitiator can be divided into free radical photoinitiators, photo-acid generators (cationic photoinitiators) and photo-base generators. In the present application, the photoinitiator is preferably a free radical photoinitiator and / or a photo-base generator, more preferably a free radical photoinitiator and a photo-base generator; the mass ratio of the free radical photoinitiator and the photo-base generator is preferably 1:(2-5), more preferably 1:(3-5), and even more preferably 1:4.

[0129] There is no particular limitation on the free radical photoinitiator suitable for use in the present application, but it is preferably a visible light photosensitizer having photoinitiating activity. Suitable photosensitizers are preferably Irgacure 784, neomethylene blue, thionine, basic red 2, basic yellow, pinacyl chloride, rhodamine 6G, malachite green, ethyl violet, Victoria blue R, lapis lazuli blue, quinaldine red, crystal violet, brilliant green, astrazon orange G, darrow red, pironine Y, rose Bengal, patulin Y, Michler's ketone, aminocoumarin, pyrillium I, diiodofluorescein, anthocyanin, methylene blue, 2,5-bis{[4-(diethylamino)-2-methylphenyl]methylene}cyclopentanone, leuconitrile and malachite green, etc. These substances can be used alone or in combination of two or more.

[0130] The photo-base generator suitable for use in the present application is preferably one or more of carbamates, aminoketones, benzoylformamides, cobalt amine complexes, quaternary ammonium salts, tetraphenylborate salts and carboxylate salts, more preferably tetraphenylborate salts, triphenyl-n-butyl borate, 2-isopropylthioxanthone, 4-dimethylaminobenzoic acid ethyl ester.

[0131] In some preferred embodiments of the present application, the photoinitiator suitable for use in the present application is selected from at least one of Irgacure 784, basic red 2, patulin Y, methylene blue, rhodamine 6G, diiodofluorescein, aminocoumarin, tetraphenylborate salt, triphenyl-n-butyl borate, 2-isopropylthioxanthone, 4-dimethylaminobenzoic acid ethyl ester.

[0132] The co-initiator is preferably an initiation-active compound containing N atoms, more preferably one or more of ethylenediamine, triethanolamine, N-methyldiethanolamine, N-butyldiethanolamine, N-phenylglycine, 2-(4-chlorophenyl)-4,5-diphenylimidazole and 4-dimethyl-aminobenzoic acid ethyl ester.

[0133] According to the present application, the photopolymer holographic recording material preferably further comprises 10-50 parts by weight of a solvent; the composition is mixed by the solvent to form a uniform system; the content of the solvent is more preferably 20-50 parts by weight, more preferably 30-50 parts by weight, more preferably 30-40 parts by weight, and most preferably 32-35 parts by weight; in the examples provided in the present application, the content of the solvent is specifically 33 parts by weight; in the present application, the solvent is preferably a non-reactive solvent, more preferably one or more of halogenated hydrocarbon solvents, ketone solvents, alcohol solvents, ester solvents, hydrocarbon solvents and amide solvents; wherein the halogenated hydrocarbon solvents are, for example, dichloromethane, dichloroethane, chloroform, etc.; the ketone solvents are, for example, acetone, butanone, etc.; the alcohol solvents are, for example, ethanol, butanol, etc.; the ester solvents are, for example, ethyl acetate, butyl acetate, etc.; the hydrocarbon solvents are, for example, aliphatic hydrocarbon solvents or aromatic hydrocarbon solvents, etc.; the amide solvents are, for example, DMAC, DMF, etc. Since a lower boiling point is beneficial to subsequent film preparation process, an organic solvent with a boiling point of 120°C or lower at normal pressure is preferably used in the present application. In addition, it should be noted that each of the above-mentioned solvents can be used alone or in the form of a mixed solvent formed by using a plurality of solvents.

[0134] In the present application, 0.1-5 parts by weight of other additives are preferably further included; as long as the technical effects of the present application are not affected, other additives commonly used in the art, such as one or more of chain transfer agents, leveling agents, wetting agents, defoaming agents and tackifiers, as well as polyurethane, thermoplastic polymer, 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 oxide) can be added as additional auxiliaries and additives according to actual production needs.

[0135] The present application also provides a grating, which is a resin film with a grating structure; the resin film is formed from the above-mentioned photopolymer holographic recording material containing a mercapto compound and an epoxy compound.

[0136] The present application also provides a method for preparing a grating, comprising: S1) mixing the above-mentioned photopolymer holographic recording material containing a mercapto compound and an epoxy compound to obtain a mixture; S2) film-forming the mixture and forming a grating structure to obtain a grating.

[0137] The above-mentioned photopolymer composition is mixed to obtain a mixture, and in some specific embodiments of the present application, the mixture is in the form of a melt or a liquid obtained by mixing the photopolymer composition.

[0138] In the present application, the composition can be mixed in a suitable container in the appropriate proportions and, if necessary, can be subjected to mechanical stirring or the like to ensure uniform mixing. There is no particular limitation on the temperature at which mixing is carried out, and in general mixing can be carried out at room temperature or under heating (preheating).

[0139] In other specific embodiments, the mixing step can be carried out under suitable heating conditions. The heating temperature can be determined in accordance with the activity of the components in the photopolymer composition and the desired viscosity of the system. In some cases, it can be necessary to increase the mixing temperature to obtain a lower viscosity and to obtain a homogeneous mixture of the components. In addition, it can also be necessary to control the degree of heating so as not to overheat and to avoid excessive polymerization in the unnecessary processing window, which can cause difficulties in subsequent processing.

[0140] In some preferred embodiments of the present application, the temperature used in the mixing step is above 10°C, more preferably above 30°C, and below 90°C, preferably below 60°C. The resulting mixed solution can be used immediately or stored for a short time at the processing temperature and then used.

[0141] In addition, in order to prevent photopolymerization during mixing, the addition of the photosensitive dye compound and the co-initiator should be carried out last and in a darkroom or under a protective lamp that is inert to the photosensitive dye compound.

[0142] The mixture is formed into a film and a grating structure is formed, preferably the mixture is formed into a film on a substrate and a grating structure is formed by exposure treatment; the exposure treatment preferably uses coherent light. In the present application, this step is preferably carried out as follows: 1) the mixture is coated on a glass or high-transparency plastic film substrate in a darkroom or under a protective lamp, using devices known to those skilled in the art such as doctor blade devices (doctor blade, knife roller, Commabar, etc.) or slit nozzles, etc.; 2) the mixture is left to stand to allow the solvent to evaporate, to increase the evaporation rate, the temperature can be increased appropriately, or the process can be carried out at room temperature under low pressure or in a blowing environment; 3) after the solvent has been completely removed, a glass substrate or a high-transparency plastic protective film is placed on the surface of the polymer film formed by the mixture, and then cut to an appropriate size and stored in the dark for use, to obtain a structure as shown in Figure 1 Figure 2 4) the dry plate obtained in step 3) is exposed to laser interference in a double-beam light path (the light path is as shown in Figure 2 5) the holographic polymer grating obtained in step 4) is irradiated with an LED lamp, a daylight lamp or a UV lamp until it is completely fixed and bleached.

[0143] In some embodiments of the present application, two coherent light beams can be used to expose the polymer film simultaneously from one side of the film (transmission grating); in other embodiments, two coherent light beams can be used to expose the polymer film from both sides of the film (reflection grating).

[0144] In addition, the grating obtained by the present application can be a planar grating or a curved grating with a certain curvature. The method for preparing the curved grating is not particularly limited, and in some embodiments, a substrate with a certain curvature can be used to form a film and expose the film. In other embodiments, a planar substrate can be used to form a film, expose the film, and then process the film into a curved grating with a certain curvature.

[0145] The present application also provides the use of the grating described above. Without limitation, the grating described above containing a photopolymer film can be used in various holographic display systems in the art, and can be used alone or in combination with other optical elements.

[0146] Further, the present application provides a diffraction grating element for a holographic optical waveguide display system. The diffraction grating element comprises a substrate layer and a photopolymer film layer. The photopolymer film layer is formed from a photopolymer holographic recording material containing a mercapto compound and an epoxy compound; the substrate layer, the photopolymer holographic recording material containing a mercapto compound and an epoxy compound are the same as described or defined above.

[0147] In some preferred embodiments, the grating element is formed by sandwiching a photopolymer film layer between a substrate layer and a protective layer. The photopolymer film layer has at least two non-contiguous exposure regions, which can be exposed by a set of identical coherent light sources either simultaneously or sequentially, and after post-processing, two grating regions are formed in one grating element.

[0148] Typically, the grating element has a regular shape for ease of use and installation, which can be in the shape of a long strip, a square piece, or a circular piece, etc.

[0149] In some preferred embodiments, the grating element of the present application has the shape of a long strip, and at both end regions in the length direction of the long strip, there are exposure regions processed by exposure, etc., and in each exposure region, a grating (holographic recording) structure is formed. The two exposure regions are physically not connected. Typically, one exposure region can be used as a coupling-in grating region, and the other exposure region can be used as a coupling-out grating region.

[0150] The grating element of the present application can be used in a holographic optical waveguide display device, and is particularly suitable for a head-mounted device (such as an AR display eyeglass device) of an augmented reality (AR) with strict requirements on diffraction efficiency, refractive index modulation, light transmittance, etc., and a head-up display (HUD) of an automobile or an aircraft.

[0151] In order to further illustrate the present application, a photopolymer holographic recording material containing a mercapto compound and an epoxy compound and a grating provided by the present application are described in detail below in combination with examples.

[0152] The reagents used in the following examples are all commercially available.

[0153] Example 1

[0154] Compound 1, ethoxylated bisphenol A diacrylate, 9,9-bis(4- glycidoxyphenyl)fluorene, solvent butyl acetate, film-forming agent cellulose acetate butyrate, were added into a sample bottle, and stirred at room temperature until completely clear. Then, the initiator aminochromocoumarin, 4-dimethylaminoethyl benzoate, and 2-(4-chlorophenyl)-4,5-diphenylimidazole were added under light or red light, and stirred for 30 min to obtain a uniform and clear photopolymer solution (the ratio of all components is shown in Table 1). Subsequently, the mixed solution was coated on a 1 mm thick glass substrate under light or red light, with a coating thickness of about 20 μm. After the solvent completely evaporated, a 40 μm thick TAC protective film was covered on the surface to obtain a photopolymer dry plate. Finally, the obtained dry plate was exposed to interference light with an energy density of 15 mJ / cm2of 450 nm laser light in a two-beam optical path as shown in Figure 2 After about 30 min of bleaching under UV light, a reflective holographic grating was formed. 2

[0155] Table 1 Composition of Example 1

[0156] Composition Content Aminocoumarin 0.2％ Ethyl 4-dimethylaminobenzoate 0.8％ 2-(4-chlorophenyl)-4,5-diphenylimidazole 1％ Compound 1 20％ Ethoxylated bisphenol A diacrylate 15％ 9,9-bis(4-epoxypropyloxyphenyl)fluorene 10％ Cellulose acetate butyrate 20％ Butyl acetate 33％

[0157] The diffraction efficiency of the reflective holographic grating obtained in Example 1 was tested. A 450 nm LED blue light point source was used as a test light source, and the relative diffraction efficiency at different angles was tested by changing the included angle between the grating and the test light beam using a turntable. It was found that the diffraction efficiency of the reflective grating was greater than 90%, the angle selectivity was large, and the refractive index modulation could reach 0.05. The thickness shrinkage rate of the photopolymer film after exposure was calculated by the Bragg angle offset value, and was 1.3%.

[0158] The thermal stability of the reflective holographic grating obtained in Example 1 was tested. White light was used as a light source, and the transmittance curve of the white light was tested by a spectrometer after the grating was heated at room temperature (25℃) and 100℃ for 3 hours, respectively, as shown in​Figure 4 As shown, the transmittance curve of the grating remained unchanged after heat treatment.

[0159] After the photopolymer film obtained in Example 1 was completely bleached and cured, it was peeled off from the substrate, and its tensile strength at break was measured to be approximately 76 MPa.

[0160] Example 2

[0161] Compound 2,9,9-di(methyl acrylate) fluorene, bisphenol A diglycidyl ether, butyl acetate solvent, and cellulose acetate butyrate film-forming agent were added to a sample vial. The mixture was stirred at room temperature until completely clear. Then, under light-shielded or red light conditions, initiator 2,5-bis{[4-(diethylamino)-2-methylphenyl]methylene}, tetraphenylboron salt, and N-phenylglycine were added and stirred for 30 min to obtain a homogeneous and clear photopolymer solution (all component ratios are shown in Table 2). Subsequently, under light-shielded or red light conditions, the mixed solution was coated onto a 1 mm thick glass substrate, with a coating thickness of approximately 20 μm. After horizontal standing to allow complete solvent evaporation, a 40 μm thick TAC protective film was applied to the surface to obtain a photopolymer dry plate. The final dry plate was then subjected to [further processing / processing]. Figure 2 The dual-beam optical path shown uses an energy density of 25 mJ / cm². 2 The 450nm laser interference exposure is followed by UV lamp irradiation for about 30 minutes for fixing and bleaching to form a reflective holographic grating.

[0162] Table 2. Composition of the composition in Example 2

[0163] Composition Content 2,5-bis{[4-(diethylamino)-2-methylphenyl]methylene} 0.2％ Tetraphenylborate 0.8％ N-phenylglycine 1％ Compound 2 20％ 9,9-bis(methyl acrylate)fluorene 15％ Bisphenol A diglycidyl ether 10％ Cellulose acetate butyrate 20％ Butyl acetate 33％

[0164] The diffraction efficiency of the reflective holographic grating obtained in Example 2 was tested using a 450nm LED blue light source as the test light source. A turntable was used to change the angle between the grating and the test beam, and the relative diffraction efficiency at different angles was tested. The results showed that the reflective grating obtained in this example had a diffraction efficiency greater than 95%, high angle selectivity, and a refractive index modulation greater than 0.04. The thickness shrinkage rate of the photopolymer film after exposure was calculated to be 1.5% using the Bragg angle offset.

[0165] The thermal stability of the reflective holographic grating obtained in Example 2 was tested. Using white light as the light source, a spectrometer was used to measure the transmittance curves of the grating to white light after heating at room temperature (25°C) and 100°C for 3 hours, respectively. Figure 5 As shown, the transmittance curve of the grating remained unchanged after heat treatment.

[0166] After the photopolymer film obtained in Example 2 was completely bleached and cured, it was peeled off from the substrate, and its tensile strength at break was measured to be approximately 82 MPa.

[0167] Comparative Example 1

[0168] In a sample bottle, add ethoxylated bisphenol A diacrylate, 9,9-bis(4- glycidyloxyphenyl)fluorene, solvent butyl acetate, film-forming agent cellulose acetate butyrate, after stirring at room temperature until completely clear, add initiator aminocoumarin, N-phenyl glycine under red light or light and stir for 30 min to get a uniform clear photopolymer solution (all ingredients are shown in Table 3). Then the mixed solution is coated on a 1 mm thick glass substrate under red light or light, the coating thickness is about 20 μm, and after the solvent is completely volatilized, a 40 μm thick TAC protective film is covered on the surface, and a photopolymer dry plate is obtained. Finally, the obtained dry plate is exposed in a double-beam optical path as shown in Figure 2 2 with an energy density of 15 mJ / cm 2 of 450 nm laser interference, and after about 30 min of bleaching under UV lamp, a reflective holographic grating is formed.

[0169] Table 3 Composition of Comparative Example 1

[0170] Composition Content Aminocoumarin 0.2％ N-phenylglycine 0.8％ Ethoxylated bisphenol A diacrylate 20％ 9,9-bis(4-epoxypropyloxyphenyl)fluorene 15％ Cellulose acetate butyrate 20％ Butyl acetate 44％

[0171] The diffraction efficiency of the reflective holographic grating obtained in Comparative Example 1 is tested, and a 450 nm LED blue light point source is used as a test light source. The relative diffraction efficiency at different angles is tested by changing the angle between the grating and the test light beam using a turntable. The diffraction efficiency of the reflective grating obtained in Comparative Example 1 is greater than 90%, and the refractive index modulation is about 0.03. The thickness shrinkage rate of the photopolymer film after exposure is calculated by the Bragg angle offset value, which is 2.6%.

[0172] The thermal stability of the reflective holographic grating obtained in Comparative Example 1 is tested, and white light is used as a light source. The transmittance curve of white light is tested by a spectrometer after heating at room temperature (25℃) and 100℃ for 3 hours, respectively, as shown in Figure 6 After heat treatment, the absorption peak shifts, indicating that the grating deforms at 100℃.

[0173] After the photopolymer film obtained in Comparative Example 1 is completely bleached and solidified, it is peeled off from the substrate, and the tensile strength at break is measured to be about 53 MPa.

[0174] Comparative Example 2

[0175] In a sample bottle, 9,9-bis(methyl acrylate) fluorene, bisphenol A diglycidyl ether, solvent butyl acetate, film former cellulose acetate butyrate were added, stirred at room temperature until completely clear, then added initiator 2,5-bis{[4-(diethylamino)-2-methylphenyl]methylene}, N-phenylglycine under red light or dark and stirred for 30 min to obtain a uniform clear photopolymer solution (all ingredient ratios are shown in Table 4). Then the mixed solution was coated on a 1 mm thick glass substrate under red light or dark, the coating thickness was about 20 μm, and after the solvent completely volatilized, a 40 μm thick TAC protective film was covered on the surface to obtain a photopolymer dry plate. Finally, the obtained dry plate was exposed in a double-beam optical path as shown in Figure 2 with a 450 nm laser with an energy density of 25 mJ / cm 2 , and after bleaching and fixing by UV lamp irradiation for about 30 min, a reflective holographic grating was formed.

[0176] Table 4 Composition of Comparative Example 2

[0177] Composition Content 2,5-bis{[4-(diethylamino)-2-methylphenyl]methylene} 0.2％ N-phenylglycine 0.8％ Ethoxylated bisphenol A diacrylate 20％ Bisphenol A diglycidyl ether 15％ Cellulose acetate butyrate 20％ Butyl acetate 44％

[0178] The diffraction efficiency of the reflective holographic grating obtained in Comparative Example 2 was tested, and a 450 nm LED blue light point source was used as a test light source. The relative diffraction efficiency at different angles was tested by changing the angle between the grating and the test beam using a turntable. The diffraction efficiency of the reflective grating obtained in Comparative Example 2 was greater than 90%, and the refractive index modulation was greater than 0.02. The thickness shrinkage rate of the photopolymer film after exposure was calculated by the Bragg angle offset value to be 2.2%.

[0179] The thermal stability of the reflective holographic grating obtained in Comparative Example 2 was tested, and white light was used as a light source. The transmittance curve of the white light was tested by a spectrometer after heating at room temperature (25°C) and 100°C for 3 hours, respectively, as shown in Figure 7 , the absorption peak shifted after heat treatment, indicating that the grating was deformed at 100°C.

[0180] After the photopolymer film obtained in Comparative Example 2 was completely bleached and solidified, it was peeled off from the substrate, and the tensile strength at break was measured to be about 48 MPa.

Claims

1. A photopolymer holographic recording material containing a mercapto compound, an acrylate compound and an epoxy compound, characterized in that, Comprising: The polymerized monomers include a mercapto compound, an epoxy compound, and an acrylate compound; The mass ratio of the mercapto compound, the epoxy compound, and the acrylate compound is (1-3):(0.5-2):(1-2); The mercapto compound is selected from one or more of Compound 1-Compound 7:

2. The photopolymer holographic recording material according to claim 1, characterized in that, The epoxy compound is shown as Formula (II): Q and Q' are each independently selected from a group containing an epoxy structure; Z is a heteroatom, a single bond, a substituted or unsubstituted alkylene group; the substituent in the substituted alkylene group is selected from one or two of a C6-C30 aryl group, a C1-C10 alkyl group, and a C1-C10 alkoxy group, or the above groups are bonded by a single bond; E and E' are each independently selected from a heteroatom; Ar and Ar' are each independently selected from a group containing an aryl group; or Ar and Ar' are connected by a substituent; m and m' are each independently an integer of 0-3, and are not simultaneously 0; when m is 0, E is a C1-C10 alkyl group; when m' is 0, E' is a C1-C10 alkyl group.

3. The photopolymer holographic recording material of claim 1, wherein The acrylate compound is shown as Formula (III): Q1 and Q1' are each independently selected from a group containing an acryloyl structure or a methacryloyl structure; Z1 is a heteroatom, a single bond, a substituted or unsubstituted alkylene group; the substituent in the substituted alkylene group is selected from one or two of a C6-C30 aryl group, a C1-C10 alkyl group, and a C1-C10 alkoxy group, or the above groups are bonded by a single bond; E1 and E1' are each independently selected from a heteroatom; Ar1 and Ar1' are each independently selected from a group containing an aryl group; or Ar1 and Ar1' are connected by a substituent; m1 and m1' are each independently an integer of 0-3, and are not simultaneously 0; when m1 is 0, E1 is a C1-C10 alkyl group; when m1' is 0, E1' is a C1-C10 alkyl group.

4. The photopolymer holographic recording material of claim 1, wherein The epoxy compound is a polyphenol type glycidyl epoxy monomer; the acrylate compound is 9,9-di(methyl acrylate) fluorene.

5. The photopolymer holographic recording material of claim 1, wherein, Further comprising 10-50 parts by weight of a solvent and 0.1-5 parts by weight of other additives; The film-forming agent is selected from one or more of a polymer containing a vinyl acetate monomer unit, a cellulose ester, a cellulose ether, a polyvinyl alcohol, a polyvinyl acetal, a polyurethane, a block copolymer containing a styrene monomer unit and / or a butadiene monomer unit, and a polyvinyl pyrrolidone; The photoinitiator is selected from a free radical type photoinitiator and / or a photobase generator; the radical photoinitiator is selected from one or more of Irgacure 784, neomethylene blue, thionine, basic red 2, basic yellow, pinacyl chloride, rhodamine 6G, malachite green, ethyl violet, Victoria blue R, lapis lazuli blue, quinaldine red, brilliant green, basic orange G, darrow red, pyronine Y, rose Bengal, eosin Y, Michler's ketone, aminocoumarin, pyrylium iodonium, diiodofluorescein, cyanine, methylene blue, 2,5-bis{[4-(diethylamino)-2-methylphenyl]methylene}cyclopentanone, azure A, crystal violet, and malachite green; the photobase generator is selected from one or more of a carbamate photobase generator, an aminoketone photobase generator, a benzoylformamide photobase generator, a cobalamin complex photobase generator, a quaternary ammonium salt photobase generator, a tetraphenylborate salt photobase generator, and a carboxylate salt photobase generator; the co-initiator is selected from one or more of ethylenediamine, triethanolamine, N-methyldiethanolamine, N-butyldiethanolamine, N-phenylglycine, 2-(4-chlorophenyl)-4,5-diphenylimidazole, and 4-dimethyl-aminobenzoic acid ethyl ester.

6. An optical grating, characterized by the optical grating is a resin film having an optical grating structure; the resin film is formed from the photopolymer holographic recording material containing a mercapto compound, an acrylate compound, and an epoxy compound according to any one of claims 1 to 5. the radical photoinitiator is selected from one or more of Irgacure 784, neomethylene blue, thionine, basic red 2, basic yellow, pinacyl chloride, rhodamine 6G, malachite green, ethyl violet, Victoria blue R, lapis lazuli blue, quinaldine red, brilliant green, basic orange G, darrow red, pyronine Y, rose Bengal, eosin Y, Michler's ketone, aminocoumarin, pyrylium iodonium, diiodofluorescein, cyanine, methylene blue, 2,5-bis{[4-(diethylamino)-2-methylphenyl]methylene}cyclopentanone, azure A, crystal violet, and malachite green; the photobase generator is selected from one or more of a carbamate photobase generator, an aminoketone photobase generator, a benzoylformamide photobase generator, a cobalamin complex photobase generator, a quaternary ammonium salt photobase generator, a tetraphenylborate salt photobase generator, and a carboxylate salt photobase generator; the co-initiator is selected from one or more of ethylenediamine, triethanolamine, N-methyldiethanolamine, N-butyldiethanolamine, N-phenylglycine, 2-(4-chlorophenyl)-4,5-diphenylimidazole, and 4-dimethyl-aminobenzoic acid ethyl ester. the optical grating is a resin film having an optical grating structure; the resin film is formed from the photopolymer holographic recording material containing a mercapto compound, an acrylate compound, and an epoxy compound according to any one of claims 1 to 5.

Images