Patent Application
20240118660
This application relates to the field of polymer resin materials, and in particular, to a holographic recording medium, a holographic polymer material, a preparation method therefor, and a display device.
A crosslinked-network-based holographic polymer material features solvent-free preparation, ease of processing, a stable size, thick film recording, and the like. The holographic polymer material plays an important role in many fields. The holographic polymer material is mainly obtained through polymerization reactions in two stages. In a first stage, a non-free radical reactive monomer (referred to as a first-order monomer) forms a first-order crosslinked network through a polymerization reaction, to provide a mechanical support, and a free radical reactive monomer (referred to as a second-order monomer) is stabilized in the first-order crosslinked network for subsequent holographic recording. The second-order monomer does not react in a process of forming the first-order crosslinked network. In a second stage, a photoinitiator generates a free radical under irradiation of a coherent laser, so that the second-order monomer undergoes a photopolymerization reaction in a coherent bright region, to induce a monomer in a coherent dark region to diffuse to the coherent bright region and participate in the photopolymerization reaction, making polymer densities and refractive indexes of the coherent bright region and the coherent dark region different. Holographic information is recorded in a form of a holographic grating. Currently, in most cases, micro-phase separation from the first-order crosslinked network occurs on a polymer generated after the photopolymerization reaction of the second-order monomer in the coherent bright region. As a micro-phase separation degree increases in a photopolymerization reaction process, diffraction efficiency increases, but a transmittance decreases. Consequently, it is difficult to prepare a holographic polymer material with high diffraction efficiency and a high transmittance.
This application provides a holographic recording medium, a holographic polymer material, a preparation method therefor, and a display device, to achieve advantages of high diffraction efficiency and a high transmittance of the holographic polymer material.
According to a first aspect, this application provides a holographic recording medium, including a first-order crosslinked network, a photoinitiator, and a second-order monomer. The first-order crosslinked network provides a mechanical support for the holographic recording medium. The second-order monomer is a monomer with a free radical reactivity. The photoinitiator is used to absorb light and generate a free radical, to polymerize the second-order monomer. The holographic recording medium includes an ester group (I), a urethane group (II), a carbamido group (III), an allophanate group (IV), and an amide group (V). Groups linked to the ester group (I), the urethane group (II), the carbamido group (III), the allophanate group (IV), and the amide group (V) are separately selected from at least one of the following: alkyl, alkoxy, alkenyl, or aryl.
According to the holographic recording medium provided in this application, the ester group (I), the urethane group (II), the carbamido group (III), the allophanate group (IV), and the amide group (V) are introduced, so that compatibility between monomers and between the second-order monomer and the first-order crosslinked network can be increased on the one hand, and phase separation of a polymer generated by the second-order monomer from the first-order crosslinked network can be suppressed on the other hand. Therefore, a holographic polymer material with a high transmittance and high diffraction efficiency can be prepared.
In a possible implementation of this application, the second-order monomer accounts for 10% to 80% of a total weight of the holographic recording medium, and may further account for 30% to 70%. A weight percentage of the second-order monomer in the holographic recording medium is limited, and a weight percentage of the photoinitiator in the holographic recording medium is low, which is about 0.1% to 3%. This is equivalent to that a weight percentage of the first-order crosslinked network in the holographic recording medium is also limited. Therefore, a finally obtained holographic polymer material has a high transmittance and high diffraction efficiency.
In a possible implementation of this application, after being illuminated, the holographic recording medium includes at least one of the following: the ester group (I), the urethane group (II), the carbamido group (III), the allophanate group (IV), and the amide group (V). Therefore, the holographic recording medium includes at least one of the following: the ester group (I), the urethane group (II), the carbamido group (III), the allophanate group (IV), and the amide group (V) before and after illumination. In this way, the compatibility between the monomers and between the second-order monomer and the first-order crosslinked network can be improved, and in addition, phase separation of the second-order polymer generated through a photopolymerization reaction of the second-order monomer from the first-order crosslinked network can be suppressed in a holographic recording process. Therefore, both the transmittance and the diffraction efficiency of the holographic polymer material are improved.
In a possible implementation of this application, the holographic recording medium includes at least one of the following: the ester group (I), the urethane group (II), the carbamido group (III), the allophanate group (IV), and the amide group (V), so that an infrared spectrum of the holographic recording medium includes a first characteristic absorption peak and a second characteristic absorption peak. A wave number range of the first characteristic absorption peak is 1760 cm−1 to 1650 cm−1. A wave number range of the second characteristic absorption peak is 1650 cm−1 to 1610 cm−1. A non-reactive polar group included in the holographic recording medium may be characterized by using the wave number ranges of the two characteristic absorption peaks of the infrared spectrum. The holographic recording medium of which the 1760 cm−1 to 1650 cm−1 and the second characteristic absorption peak whose wave number range is 1650 cm−1 to 1610 cm−1 is selected, so that a holographic polymer material with a high transmittance and high diffraction efficiency can be prepared.
In a possible implementation of this application, a ratio of a peak area of the first characteristic absorption peak to a peak area of the second characteristic absorption peak ranges from 5 to 30. The holographic recording medium whose ratio of the peak area of the first characteristic absorption peak to the peak area of the second characteristic absorption peak ranges from 5 to 30 is used, so that a ratio of a peak area of a first characteristic absorption peak to a peak area of a second characteristic absorption peak of an infrared spectrum of a prepared polymer material ranges from 0.5 to 5. Therefore, the prepared holographic polymer material can have a high transmittance and high diffraction efficiency.
In a possible implementation of this application, the second-order monomer includes at least one of the following: acrylate, methacrylate, maleate, fumarate, maleimide, acrylamide, vinyltoluene, vinylcarbazole, N-vinylpyrrolidone, N,N-dimethylacrylamide, methacrylonitrile, methacrylamide, methacrylic acid, and acrylic acid. With these second-order monomers, the holographic recording medium may include at least one of the following: the ester group (I), the urethane group (II), the carbamido group (III), the allophanate group (IV), and the amide group (V), so that the compatibility between the monomers and between the second-order monomer and the first-order crosslinked network can be increased on the one hand, and phase separation of the polymer generated by the second-order monomer from the first-order crosslinked network can be suppressed on the other hand.
In a possible implementation of this application, a refractive index of at least one second-order monomer is greater than 1.505. A high refractive index of the second-order monomer helps improve a refractive index contrast between the second-order monomer and the first-order monomer, and makes it easier to implement both a high transmittance and high diffraction efficiency.
In a possible implementation of this application, the first-order crosslinked network is generated through a polymerization reaction of the first-order monomer, and the first-order monomer generally does not have a free radical reactivity. Therefore, when the holographic recording medium is illuminated, the first-order monomer does not undergo the photopolymerization reaction, which can avoid interference to a subsequent photopolymerization reaction.
In a possible implementation of this application, the photoinitiator includes at least one of the following: benzoin and a derivative thereof, benzyl ketal, an acrylphosphine oxide, ketocoumarin, amino acid, rose bengal, methylene blue, a triazine compound, and alkylamine. With these photoinitiators, efficiency of the photopolymerization reaction can be improved.
According to a second aspect, this application further provides a method for preparing a holographic recording medium. The preparation method includes the following steps: mixing a first-order monomer, a second-order monomer, and a photoinitiator at room temperature to obtain a mixed solution; and performing curing treatment on the mixed solution, so that the first-order monomer undergoes a polymerization reaction to generate a first-order crosslinked network, to obtain a holographic recording medium. The holographic recording medium includes at least one of the following: an ester group (I), a urethane group (II), a carbamido group (III), an allophanate group (IV), and an amide group (V).
According to the holographic recording medium prepared in this application, the ester group (I), the urethane group (II), the carbamido group (III), the allophanate group (IV), and the amide group (V) are introduced, so that compatibility between monomers and between the second-order monomer and the first-order crosslinked network in the holographic recording medium can be increased on the one hand, and phase separation of a polymer generated by the second-order monomer from the first-order crosslinked network can be suppressed during preparation of a holographic polymer material on the other hand. Therefore, a holographic polymer material with a high transmittance and high diffraction efficiency can be prepared.
According to a third aspect, this application further provides a holographic polymer material. The holographic polymer material includes a first-order crosslinked network and a second-order polymer. The first-order crosslinked network provides a mechanical support for the holographic polymer material. The second-order polymer is used to form a refractive index distribution for recording holographic information. The holographic polymer material includes at least one of the following: an ester group (I), a urethane group (II), a carbamido group (III), an allophanate group (IV), and an amide group (V). Groups linked to the ester group (I), the urethane group (II), the carbamido group (III), the allophanate group (IV), and the amide group (V) are separately selected from at least one of the following: alkyl, alkoxy, alkenyl, or aryl. The holographic polymer material has advantages of a high transmittance and high diffraction efficiency.
In a possible implementation of this application, the holographic polymer material includes at least one of the following: the ester group (I), the urethane group (II), the carbamido group (III), the allophanate group (IV), and the amide group (V), so that an infrared spectrum of the holographic polymer material includes a first characteristic absorption peak and a second characteristic absorption peak. A wave number range of the first characteristic absorption peak is 1760 cm−1 to 1702 cm−1. A wave number range of the second characteristic absorption peak is 1702 cm−1 to 1640 cm−1. A non-reactive polar group included in the holographic polymer material may be represented using the wave number ranges of the two characteristic absorption peaks of the infrared spectrum, so that the holographic polymer material has a high transmittance and high diffraction efficiency.
In a possible implementation of this application, a ratio of a peak area of the first characteristic absorption peak to a peak area of the second characteristic absorption peak ranges from 0.5 to 5. Therefore, the holographic polymer material has a high transmittance and high diffraction efficiency.
In a possible implementation of this application, the second-order polymer is generated by polymerizing a second-order monomer under initiation of a free radical. The second-order monomer is a monomer with a free radical reactivity. The second-order monomer includes at least one of the following: acrylate, methacrylate, maleate, fumarate, maleimide, acrylamide, vinyltoluene, vinylcarbazole, N-vinylpyrrolidone, N,N-dimethylacrylamide, methacrylonitrile, methacrylamide, methacrylic acid, and acrylic acid. With these second-order monomers, the holographic polymer material may include at least one of the following: the ester group (I), the urethane group (II), the carbamido group (III), the allophanate group (IV), and the amide group (V), so that phase separation of the polymer generated by the second-order monomer from the first-order crosslinked network can be suppressed.
In a possible implementation of this application, a refractive index of at least one second-order monomer is greater than 1.505. A high refractive index of the second-order monomer helps improve a refractive index contrast between the second-order monomer and the first-order monomer, and makes it easier to implement both a high transmittance and high diffraction efficiency.
According to a fourth aspect, this application further provides a method for preparing a holographic polymer material. The preparation method includes the following steps: mixing a first-order monomer, a second-order monomer, and a photoinitiator at room temperature to obtain a mixed solution; performing curing treatment on the mixed solution, so that the first-order monomer undergoes a polymerization reaction to generate a first-order crosslinked network, to obtain a holographic recording medium; and exposing the holographic recording medium under coherent light to obtain a holographic polymer material recording holographic information. The holographic polymer material prepared in this application has advantages of a high transmittance and high diffraction efficiency.
In a possible implementation of this application, the first-order monomer includes at least one of the following: polyol, polyepoxy, polyvinyl ether, polyamine, and polyisocyanate. With these first-order monomers, the prepared holographic recording medium may include at least one of the following: an ester group (I), a urethane group (II), a carbamido group (III), an allophanate group (IV), and an amide group (V), so that compatibility between monomers and between the second-order monomer and the first-order crosslinked network in the holographic recording medium can be increased on the one hand, and phase separation of a polymer generated by the second-order monomer from the first-order crosslinked network can be suppressed during preparation of the holographic polymer material on the other hand. Therefore, a holographic polymer material with a high transmittance and high diffraction efficiency can be prepared.
In a possible implementation of this application, the method further includes: performing post-treatment on the holographic polymer material, where post-treatment includes illumination or heating. Through a post-treatment step, the second-order monomer that does not completely react in the photopolymerization reaction further reacts. Therefore, a monomer conversion rate is improved.
In a possible implementation of this application, the method further includes: adding a nitrogen-containing polar monomer to the mixed solution. A specific amount of polar monomer is added to the mixed solution, so that dissolution of the photoinitiator in a monomer (for example, the second-order monomer, or the first-order monomer) can be promoted.
In a possible implementation of this application, the nitrogen-containing polar monomer may be one or more of the following: N-vinylpyrrolidone and
N,N-dimethylacrylamide. The N-vinylpyrrolidone and the N,N-dimethylacrylamide can not only promote dissolution of the photoinitiator in the monomer, but also participate in the photopolymerization reaction to prevent a solvent residue from affecting material performance.
In a possible implementation of this application, curing treatment is performed on the mixed solution, so that a thickness of the holographic polymer material is controlled to range from 5 micrometers (μm) to 50 μm, which may further range from 10 μm to 30 μm. Therefore, a holographic polymer material with a high transmittance and diffraction efficiency can be prepared.
According to a fifth aspect, this application further provides a display device. The display device is obtained by using the holographic recording medium in the first aspect and any possible implementation of the first aspect through a photopolymerization reaction, or includes the holographic polymer material in the third aspect and any possible implementation of the third aspect. The display device is, for example, a head up display (head up display, HUD) device.
According to a sixth aspect, this application further provides a storage device. The storage device is obtained by using the holographic recording medium in the first aspect and any possible implementation of the first aspect through a photopolymerization reaction, or includes the holographic polymer material in the third aspect and any possible implementation of the third aspect. The storage device may be, for example, a holographic memory (holographic memory).
According to a seventh aspect, this application further provides an anti-counterfeiting label. The anti-counterfeiting label is obtained by using the holographic recording medium in the first aspect and any possible implementation of the first aspect through a photopolymerization reaction, or includes the holographic polymer material in the third aspect and any possible implementation of the third aspect.
For beneficial effects of the fifth aspect and the sixth aspect, refer to the beneficial effects of the first aspect or the third aspect. Details are not described herein again.
To make objectives, technical solutions, and advantages of this application clearer, the following further describes this application in detail with reference to the accompanying drawings.
Terms used in the following embodiments are merely for the purpose of describing specific embodiments, but are not intended to limit this application. As used in the specification of this application and the appended claims, the singular expression “a”, “an”, “the foregoing”, “the”, or “this” is intended to also include expressions such as “one or more”, unless otherwise clearly indicated in the context.
Reference to “an embodiment”, “some embodiments”, or the like described in this specification indicates that one or more embodiments of this application include a specific feature, structure, or characteristic described with reference to the embodiments. Therefore, statements such as “in an embodiment”, “in some embodiments”, “in some other embodiments”, and “in other embodiments” that appear at different places in this specification do not necessarily mean referring to a same embodiment. Instead, the statements mean “one or more but not all of embodiments”, unless otherwise specifically emphasized in another manner. The terms “include” and “have” and their variants all mean “include but are not limited to”, unless otherwise specifically emphasized in another manner.
For ease of understanding, some terms in the following embodiments of this application are first described as an example.
In addition, unless otherwise stated, ordinal terms such as “first” and “second” mentioned in embodiments of this application are used to distinguish between a plurality of objects, and are not intended to limit sequences, time sequences, priorities, or importance degrees of the plurality of objects. For example, a first characteristic absorption peak and a second characteristic absorption peak are merely used to distinguish between different characteristic absorption peaks, but do not indicate different priorities, sequences, importance degrees, or the like of the two characteristic absorption peaks.
A holographic polymer material is mainly obtained through polymerization reactions in two stages. As shown in
To resolve the foregoing technical problem, an embodiment of this application provides a holographic recording medium. The holographic recording medium includes a first-order crosslinked network, a photoinitiator, and a second-order monomer. The first-order crosslinked network provides a mechanical support for the holographic recording medium. The second-order monomer is a monomer with a free radical reactivity. The photoinitiator is used to absorb light and generate a free radical, to polymerize the second-order monomer. The holographic recording medium includes at least one of the following: an ester group (I), a urethane group (II), a carbamido group (III), an allophanate group (IV), and an amide group (V). Groups linked to the ester group (I), the urethane group (II), the carbamido group (III), the allophanate group (IV), and the amide group (V) are separately selected from at least one of the following: alkyl, alkoxy, alkenyl, or aryl.
The first-order crosslinked network in the holographic recording medium includes at least one of the following: the ester group (I), the urethane group (II), the carbamido group (III), the allophanate group (IV), and the amide group (V), and/or the second-order monomer includes at least one of the following: the ester group (I), the urethane group (II), the carbamido group (III), the allophanate group (IV), and the amide group (V). Further, both the first-order crosslinked network and the second-order monomer include at least one of the following: the ester group (I), the urethane group (II), the carbamido group (III), the allophanate group (IV), and the amide group (V). In this way, compatibility between second-order monomers and between the second-order monomer and the first-order crosslinked network can be improved better, and in addition, phase separation of a second-order polymer generated through a photopolymerization reaction of the second-order monomer from the first-order crosslinked network can be suppressed in a holographic recording process. Therefore, both a transmittance and diffraction efficiency of a holographic polymer material are improved.
In an example, a structure of the ester group (I) included in the holographic recording medium is as follows:
R1 and R2 are separately selected from at least one of the following: alkyl, alkoxy, alkenyl, or aryl.
A structure of urethane group (II) included in the holographic recording medium is as follows:
R1, R2, and R3 are separately selected from at least one of the following: alkyl, alkoxy, alkenyl, or aryl.
A structure of the carbamido group (III) in the holographic recording medium is as follows:
R1 and R2 are separately selected from at least one of the following: alkyl, alkoxy, alkenyl, or aryl.
A structure of the allophanate group (IV) included in the holographic recording medium is as follows:
R1, R2, and R3 are separately selected from at least one of the following: alkyl, alkoxy, alkenyl, or aryl.
A structure of the amide group (V) included in the holographic recording medium is as follows:
R1, R2, and R3 are separately selected from at least one of the following: alkyl, alkoxy, alkenyl, or aryl.
In an embodiment of this application, the second-order monomer accounts for 10% to 80% of a total weight of the holographic recording medium, and may further account for 30% to 70%. In an example, content of the second-order monomer may be, for example, 10%, 20%, 30%, 40%, 50%, 60%, 70%, or 80%.
A weight percentage of the second-order monomer in the holographic recording medium is limited, and a weight percentage of the photoinitiator in the holographic recording medium is low, which is about 0.1% to 3%. This is equivalent to that a weight percentage of the first-order crosslinked network in the holographic recording medium is also limited. Therefore, a finally obtained holographic polymer material has a high transmittance and high diffraction efficiency.
A molecular weight of the second-order monomer may range, for example, from 30 g/mol to 3000 g/mol.
In an embodiment of this application, after being illuminated, the holographic recording medium includes at least one of the following: the ester group (I), the urethane group (II), the carbamido group (III), the allophanate group (IV), and the amide group (V). Therefore, the holographic recording medium includes at least one of the following: the ester group (I), the urethane group (II), the carbamido group (III), the allophanate group (IV), and the amide group (V) before and after illumination. In this way, the compatibility between the monomers and between the second-order monomer and the first-order crosslinked network can be improved, and in addition, phase separation of the second-order polymer generated through a photopolymerization reaction of the second-order monomer from the first-order crosslinked network can be suppressed in a holographic recording process. Therefore, both the transmittance and the diffraction efficiency of the holographic polymer material are improved.
In an embodiment of this application, the holographic recording medium includes at least one of the following: the ester group (I), the urethane group (II), the carbamido group (III), the allophanate group (IV), and the amide group (V), so that an infrared spectrum of the holographic recording medium includes a first characteristic absorption peak and a second characteristic absorption peak. A wave number range of the first characteristic absorption peak is 1760 cm−1 to 1650 cm−1. A wave number range of the second characteristic absorption peak is 1650 cm−1 to 1610 cm−1. A non-reactive polar group included in the holographic recording medium may be characterized by using the wave number ranges of the two characteristic absorption peaks of the infrared spectrum. The holographic recording medium of which the 1760 cm−1 to 1650 cm−1 and the second characteristic absorption peak whose wave number range is 1650 cm−1 to 1610 cm−1 is selected, so that a holographic polymer material with a high transmittance and high diffraction efficiency can be prepared.
In an embodiment of this application, a ratio of a peak area of the first characteristic absorption peak to a peak area of the second characteristic absorption peak ranges from 5 to 30. With the holographic recording medium whose ratio of the peak area of the first characteristic absorption peak to the peak area of the second characteristic absorption peak ranges from 5 to 30, a ratio of a peak area of a first characteristic absorption peak to a peak area of a second characteristic absorption peak of an infrared spectrum of a prepared polymer material ranges from 0.5 to 5. Therefore, the prepared holographic polymer material can have a high transmittance and high diffraction efficiency. Further, the ratio of the peak area of the first characteristic absorption peak to the peak area of the second characteristic absorption peak may be 10 to 20, so that the prepared holographic polymer material can have a higher transmittance and higher diffraction efficiency. In an example, the ratio of the peak area of the first characteristic absorption peak to the peak area of the second characteristic absorption peak may be, for example, 5, 10, 15, 20, 25, or 30.
In an embodiment of this application, the second-order monomer includes at least one of the following: acrylate, methacrylate, maleate, fumarate, maleimide, acrylamide, vinyltoluene, vinylcarbazole, N-vinylpyrrolidone, N,N-dimethylacrylamide, methacrylonitrile, methacrylamide, methacrylic acid, and acrylic acid. Further, the second-order monomer is preferably the acrylate and the acrylamide, further preferably the acrylate.
In an embodiment of this application, the acrylate includes but is not limited to methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, trimethylolpropane triacrylate, triethylene glycol dimethacrylate, phenyl methacrylate, 1,6-hexanediol diacrylate, 2-ethylhexyl acrylate, ethyl acrylate, trimethylolpropane trimethacrylate, trolox, 2-(perfluorooctyl)ethyl methacrylate, neopentyl glycol diacrylate, 1,4-butanediol diacrylate, ethoxyethyl acrylate, ethoxyethyl methacrylate, n-butyl acrylate, n-butyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate, hexyl acrylate, hexyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, butoxyethyl acrylate, butoxyethyl methacrylate, lauryl acrylate, lauryl methacrylate, isobornyl acrylate, isobornyl methacrylate, phenylacrylate, p-chlorophenyl acrylate, p-chlorophenyl methacrylate, p-bromophenyl acrylate, p-bromophenyl methacrylate, trichlorophenyl acrylate, trichlorophenyl methacrylate, tribromophenyl acrylate, tribromophenyl methacrylate, pentachlorophenyl acrylate, pentachlorophenyl methacrylate, pentabromophenyl acrylate, pentabromophenyl methacrylate, pentabromophenyl methyl acrylate, pentabromophenyl methyl methacrylate, phenoxyethyl acrylate, phenoxyethyl methacrylate, phenoxyethoxy ethyl acrylate, and dicyclopentenyl acrylate. In particular, an acrylate monomer with a high refractive index (n>1.5) is preferably used, for example, one or a mixture of 1,3-bis(phenylthio)-2-propyl acrylate, 2-([1,1′-biphenyl]-2-yloxy)ethyl acrylate, and 3-(9H-carbazole-9-yl)propane-1,2-diacrylate.
In this embodiment of this application, a refractive index of the second-order monomer may be greater than 1.505, or may be less than or equal to 1.505. For example, refractive indexes of the N,N-dimethylacrylamide, the acrylate, and the like are less than 1.505.
In an embodiment of this application, a refractive index of at least one second-order monomer is greater than 1.505. A high refractive index of the second-order monomer helps improve a refractive index contrast between the second-order monomer and the first-order monomer, and makes it easier to implement both a high transmittance and high diffraction efficiency.
In an embodiment of this application, the first-order crosslinked network is generated through a polymerization reaction of the first-order monomer, and the first-order monomer generally does not have a free radical reactivity. In some other embodiments, if the first-order monomer has a free radical reactivity, but does not affect a free radical polymerization reaction of the second-order monomer, good material performance may also be obtained. Therefore, when the holographic recording medium is illuminated, the first-order monomer does not undergo the photopolymerization reaction, which can avoid interference to a subsequent photopolymerization reaction.
In an embodiment of this application, the first-order monomer includes one or more of the following: polyol, polyepoxy, polyvinyl ether, polyamine, and polyisocyanate.
In an embodiment of this application, the polyol includes but is not limited to one or more of the following: ethylene glycol, 1,2-propanediol, 2,4-dimethyl-2,4-pentanediol, 2-n-pentylpropane-1,3-diol, tripropylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 2-ethyl-2-butyl propanediol, trimethylpentanediol, 1,3-butanediol, cyclohexanediol, 1,4-cyclohexanedimethanol, 1,6-hexanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, 3,3-dimethyl-1,2-butanediol, 1,3-cyclopentanediol, trimethylolethane, trimethylolpropane, glycerol, di(trimethylolpropane), pentaerythritol, dipentaerythritol, sorbitol, and a block copolymer that is terminated by a polyhydroxyl functional group and that contains a non-photoreactive polar group, for example, an ester or urethane.
In an embodiment of this application, the polyepoxy includes but is not limited to one or more of the following: aromatic, aromatic ester, aliphatic, and cycloaliphatic epoxy resins.
In an embodiment of this application, the polyvinyl ether includes but is not limited to one or more of the following: aromatic, aromatic ester, aliphatic, and cycloaliphatic small molecules, oligomers, or polymers with vinyl ether as a terminal group, for example, diethylene glycol divinyl ether, 1,4-butanediol divinyl ether, or polyethylene glycol divinyl ether.
In an embodiment of this application, the polyamine includes but is not limited to ethylenediamine, diethylenetriamine, triethylenetetramine, propane diamine, diaminocyclohexane, diaminobenzene, benzidine, an amine-terminated polymer with a maximum number-average molar mass of 10000 g/mol, or any mixture thereof
In an embodiment of this application, the polyisocyanate includes but is not limited to one or more of the following: butylidene diisocyanate, hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), 1,8-diisocyanato-4-(isocyanatomethyl)octane, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, bis(4,4-isocyanatocyclohexyl)methane, isocyanatomethyl-1,8-diisocyanatooctane, 1,4-cyclohexylidene diisocyanate, cyclohexane dimethylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 1,5-naphthalene diisocyanate, 2,4-diphenylmethane diisocyanate, 4,4′-diphenylmethane diisocyanate, triphenylmethane-4,4′,4″-triisocyanate, 1,3,5-tri(2-isocyanatoethyl)-1,3,5-triazine-2,4,6-trione, 1,3,5-tri(4-isocyanatobutyl)-1,3,5-triazine-2,4,6-trione, 1,3,5-tri(6-isocyanatohexyl)-1,3,5-triazine-2,4,6-trione, 1,3,5-tri(8-isocyanatooctyl)-1,3,5-triazine-2,4,6-trione, and 1,3,5-tri(10-isocyanatodecyl)-1,3,5-triazine-2,4,6-trione.
In an embodiment of this application, the photoinitiator includes at least one of the following: benzoin and a derivative thereof, benzyl ketal, an acrylphosphine oxide, ketocoumarin, amino acid, rose bengal, methylene blue, a triazine compound, and alkylamine.
Based on a same technical concept, an embodiment of this application further provides a method for preparing a holographic recording medium. As shown in
S201: Mix a first-order monomer, a second-order monomer, and a photoinitiator at room temperature to obtain a mixed solution.
S202: Perform curing treatment on the mixed solution, so that the first-order monomer undergoes a polymerization reaction to generate a first-order crosslinked network, to obtain a holographic recording medium. The holographic recording medium includes at least one of the following: an ester group (I), a urethane group (II), a carbamido group (III), an allophanate group (IV), and an amide group (V).
According to the holographic recording medium prepared in this application, the ester group (I), the urethane group (II), the carbamido group (III), the allophanate group (IV), and the amide group (V) are introduced, so that compatibility between monomers and between the second-order monomer and the first-order crosslinked network in the holographic recording medium can be increased on the one hand, and phase separation of a polymer generated by the second-order monomer from the first-order crosslinked network can be suppressed during preparation of a holographic polymer material on the other hand. Therefore, a holographic polymer material with a high transmittance and high diffraction efficiency can be prepared.
S201 and S202 should be performed in a dark place or under a safelight. Curing treatment in S202 is not limited to heating by an oven, and other curing manners may also be used.
Content of a monomer and a molecular weight of the monomer affect a ratio of peak areas of two characteristic absorption peaks of an infrared spectrum of the holographic recording medium, that is, a ratio of a first characteristic absorption peak at 1760 cm−1 to 1650 cm−1 to a second characteristic absorption peak at 1650 cm−1 to 1610 cm−1. In an embodiment of this application, content of the second-order monomer is 10 wt % to 80 wt %, which may further be 30% to 70%. In an example, the content of the second-order monomer may be, for example, 10%, 20%, 30%, 40%, 50%, 60%, 70%, or 80%.
In an embodiment of this application, a molecular weight of the first-order monomer ranges from 30 g/mol to 3000 g/mol, and a molecular weight of the second-order monomer ranges from 30 g/mol to 3000 g/mol.
In an embodiment of this application, the preparation method further includes: adding a nitrogen-containing polar monomer to the mixed solution. A specific amount of polar monomer is added to the mixed solution, so that dissolution of the photoinitiator in a monomer (for example, the second-order monomer, or the first-order monomer) can be promoted.
In an embodiment of this application, the nitrogen-containing polar monomer may be one or more of the following: N-vinylpyrrolidone and N,N-dimethylacrylamide.
In an embodiment of this application, curing treatment is performed on the mixed solution, so that a thickness of the holographic polymer material is controlled to range from 5 μm to 50 μm. Further, the thickness may range from 10 μm to 30 μm. Therefore, a holographic polymer material with a high transmittance and diffraction efficiency can be prepared.
In an example, after uniform mixing, the mixed solution including the first-order monomer, the second-order monomer, and the photoinitiator is used in a substrate, and a film may be formed by using technologies such as blade coating, casting, printing, spraying, or inkjet printing. A thickness of the film ranges from 5 μm to 50 μm. Further, the thickness may range from 10 μm to 30 μm. The substrate may be made of plastic, glass, ceramic, or a composite material including a plurality of these materials, where the plastic is a polymer.
Based on a same technical concept, an embodiment of this application further provides a holographic polymer material, including a first-order crosslinked network and a second-order polymer. The first-order crosslinked network provides a mechanical support for the holographic polymer material. The second-order polymer is used to form a refractive index distribution for recording holographic information. A refractive index of a region in which the second-order polymer is aggregated is high. A region in which there is no second-order polymer or a region in which the second-order polymer is less aggregated may also be understood as a background with a low refractive index. The second-order polymer and the background may form the refractive index distribution for recording the holographic information.
The holographic polymer material includes at least one of the following: an ester group (I), a urethane group (II), a carbamido group (III), an allophanate group (IV), and an amide group (V). Groups linked to the ester group (I), the urethane group (II), the carbamido group (III), the allophanate group (IV), and the amide group (V) are separately selected from at least one of the following: alkyl, alkoxy, alkenyl, or aryl.
In an embodiment of this application, when the holographic polymer material is used to manufacture a reflective holographic optical element, a transmittance in a range of 400 nm to 700 nm is greater than 80%, and diffraction efficiency is greater than 80%.
In an embodiment of this application, the holographic polymer material includes at least one of the following: the ester group (I), the urethane group (II), the carbamido group (III), the allophanate group (IV), and the amide group (V), so that an infrared spectrum of the holographic polymer material includes a first characteristic absorption peak and a second characteristic absorption peak. A wave number range of the first characteristic absorption peak is 1760 cm−1 to 1702 cm−1. A wave number range of the second characteristic absorption peak is 1702 cm−1 to 1640 cm−1.
In an embodiment of this application, a ratio of a peak area of the first characteristic absorption peak to a peak area of the second characteristic absorption peak ranges from 0.5 to 5. Therefore, the holographic polymer material has a high transmittance and high diffraction efficiency. Further, the ratio of the peak area of the first characteristic absorption peak to the peak area of the second characteristic absorption peak may be 1 to 5, so that both the transmittance and the diffraction efficiency of the holographic polymer material are 80%. Further, the ratio of the peak area of the first characteristic absorption peak to the peak area of the second characteristic absorption peak may be 1.1 to 3, so that the transmittance and the diffraction efficiency of the holographic polymer material are higher than the transmittance and the diffraction efficiency that are achieved when the ratio of the peak areas is 1 to 5. Further, the ratio may be 1.2 to 2.5, so that the holographic polymer material can obtain a higher transmittance and higher diffraction efficiency, which may even be 90% or higher. In an example, the ratio of the peak area of the first characteristic absorption peak to the peak area of the second characteristic absorption peak may be, for example, 0.5:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 2:1, 2.5:1, 3:1, 4:1, or 5:1.
In an embodiment of this application, the second-order polymer is generated by polymerizing a second-order monomer under initiation of a free radical. The second-order monomer is a monomer with a free radical reactivity. The second-order monomer includes at least one of the following: acrylate, methacrylate, maleate, fumarate, maleimide, acrylamide, vinyltoluene, vinylcarbazole, N-vinylpyrrolidone, N,N-dimethylacrylamide, methacrylonitrile, methacrylamide, methacrylic acid, and acrylic acid.
In an embodiment of this application, a refractive index of at least one second-order monomer is greater than 1.505. A high refractive index of the second-order monomer helps improve a refractive index contrast between the second-order monomer and the first-order monomer, and makes it easier to implement both a high transmittance and high diffraction efficiency.
The holographic polymer material may be used in a plurality of fields. In an embodiment of this application, the holographic polymer material may be used in fields of data storage, anti-counterfeiting images, holographic optical elements, holographic display, and the like. Particularly, the holographic polymer material may be used to prepare a reflective holographic grating.
As shown in
After passing through the shutter, the laser beam that is generated by the laser and that satisfies the coherence condition is split into coherent light in two directions by the beam splitter. The coherent light in the two directions separately illuminates a holographic recording medium, to obtain a holographic polymer material (holographic polymer material, HPM), to implement holographic recording.
Based on a same technical concept, an embodiment of this application further provides a method for preparing a holographic polymer material. For example, the foregoing holographic recording medium in this application is used to prepare a holographic polymer material. The preparation method includes the following step: exposing the holographic recording medium under coherent light to obtain the holographic polymer material recording holographic information.
In an embodiment of this application, the preparation method further includes: performing post-treatment on the holographic polymer material, where post-treatment includes illumination or heating. Illumination is, for example, ultraviolet irradiation. Ultraviolet irradiation is preferably for 1 minute to 20 minutes, further preferably 5 minutes to 10 minutes.
Based on a same technical concept, an embodiment of this application further provides a method for preparing a holographic polymer material. For example, a first-order monomer, a second-order monomer, and a photoinitiator are used to prepare a holographic polymer material. As shown in
S401: Mix the first-order monomer, the second-order monomer, and the photoinitiator at room temperature to obtain a mixed solution.
S402: Perform curing treatment on the mixed solution, so that the first-order monomer undergoes a polymerization reaction to generate a first-order crosslinked network, to obtain a holographic recording medium. The holographic recording medium includes at least one of the following: an ester group (I), a urethane group (II), a carbamido group (III), an allophanate group (IV), and an amide group (V).
S401 and S402 should be performed in a dark place or under a safelight. Curing treatment in S402 is not limited to heating by an oven, and other curing manners may also be used.
S403: Expose the holographic recording medium under coherent light to obtain the holographic polymer material recording holographic information. The holographic polymer material includes at least one of the following: the ester group (I), the urethane group (II), the carbamido group (III), the allophanate group (IV), and the amide group (V).
In an embodiment of this application, the preparation method further includes: performing post-treatment on the holographic polymer material, where post-treatment includes illumination or heating.
In an embodiment of this application, the preparation method further includes: adding a nitrogen-containing polar monomer to the mixed solution. A specific amount of polar monomer is added to the mixed solution, so that dissolution of the photoinitiator in a monomer (for example, the second-order monomer, or the first-order monomer) can be promoted.
In an embodiment of this application, the nitrogen-containing polar monomer may be one or more of the following: N-vinylpyrrolidone and N,N-dimethylacrylamide.
In an embodiment of this application, curing treatment is performed on the mixed solution, so that a thickness of the holographic polymer material is controlled to range from 5 μm to 50 μm. Further, the thickness may range from 10 μm to 30 μm.
In an example, after uniform mixing, the mixed solution including the first-order monomer, the second-order monomer, and the photoinitiator is used in a substrate, and a film may be formed by using technologies such as blade coating, casting, printing, spraying, or inkjet printing. A thickness of the film ranges from 5 μm to 50 μm. Further, the thickness may range from 10 μm to 30 μm. The substrate may be made of plastic, glass, ceramic, or a composite material including a plurality of these materials.
In an example, before S402, the preparation method may further include solution packaging. Solution packaging may be specifically pouring the mixed solution into a glass box in a dark room. A cavity thickness of the glass box ranges from 5 μm to 50 μm, so that the thickness of the holographic polymer material may be controlled range from 5 μm to 50 μm. Further, the cavity thickness of the glass box ranges from 10 μm to 30 μm, so that the thickness of the holographic polymer material may be controlled to range from 10 μm to 30 μm.
The following further describes the holographic polymer material in this application with reference to specific embodiments and comparison cases. However, this application is not limited to the following embodiments. In the following embodiments, an ester-containing first-order monomer and an ester-containing second-order monomer are selected to prepare a holographic polymer material. When the ester-containing first-order monomer and/or the ester-containing second-order monomer in the following embodiments are/is replaced with at least one of other ester-containing, a urethane group (II)-containing, a carbamido group (III)-containing, an allophanate group (IV)-containing, and an amide group (V)-containing first-order monomers and/or second-order monomers in the foregoing content of this application, and the preparation method and conditions described in the content of this application are used, a prepared holographic polymer material has effect equivalent to or similar to that in the following embodiments.
A. Solution preparation: Under a low-luminance safelight, 0.4-0.7 wt % of 3,3-carbonylbis(7-diethylaminocoumarin) and 1.0-1.5 wt % of N-phenylglycine are weighed as a photoinitiator (the photoinitiator accounts for 1.4-2.2 wt % of a total weight), and are added to a brown sample bottle. Then, 5 wt % of N-vinylpyrrolidone is added to dissolve a photoinitiation system. Ultrasound treatment is performed for 30 minutes to obtain a uniform solution. 15.4 wt % of isophorone diisocyanate, 34.6 wt % of polycaprolactone oxydiethylene ester, and 45 wt % of 9,9-bis[4-(2-acryloyloxyethyloxy)phenyl]fluorene. Then, ultrasound treatment is performed for 5 minutes to obtain a uniform solution, as shown in (a) in
B. Solution packaging: As shown in (b) in
C. Curing: As shown in (c) in
D. Holographic exposure: As shown in (d) in
E. Post-treatment: Exposure is performed under a high-pressure mercury lamp for 10 minutes, to obtain a holographic polymer material.
An infrared spectrum of the holographic polymer material is tested to determine a molecular composition of the holographic polymer material in this embodiment.
First-order monomers and second-order monomers used in Embodiments 2 to 30 are listed in Table 1, and photoinitiators used in Embodiments 2 to 30 and content thereof are listed in Table 2. For processes of preparing a holographic polymer material in Embodiments 2 to 30, refer to Embodiment 1. For specific process parameters, refer to Table 3.
It should be understood that in infrared spectra of holographic polymer materials prepared according to Embodiments 1 to 30, ratios of a peak area of a first characteristic absorption peak to a peak area of a second characteristic absorption peak range from 0.3 to 5.
,
Performance parameters of the holographic polymer materials prepared according to Embodiments 1 to 30 are separately tested. Test results are listed in Table 4.
A specific test process of each test item is as follows.
(1) A structure of the holographic polymer material is determined by using an infrared spectrometer.
It should be noted that a sample of the holographic polymer material is scanned in a wave number scanning range of 400 cm−1 to 4000 cm−1 by using an infrared light source in the infrared spectrometer, to obtain the infrared spectrum.
The following uses the infrared spectrum in Embodiment 1 as an example to describe the peak area of the first characteristic absorption peak and the peak area of the second characteristic absorption peak in this application. First, a baseline and a spectral interval of a characteristic absorption peak are determined. The baseline is a tangent of lowest points on two sides of the characteristic absorption peak. The spectral interval of the characteristic absorption peak is a wave number range of the characteristic absorption peak. A peak area of the characteristic absorption peak is an area surrounded by an absorption peak curve and the baseline, for example, a peak area A of the first characteristic absorption peak and a peak area of the second characteristic absorption peak in
(2) Optical performance of the holographic polymer material is measured by using an ultraviolet-visible spectrophotometer. The thickness of the film ranges from 10 μm to 30 μm. A transmittance is a transmittance T at a wavelength of 400 nm to 800 nm.
The following uses the diagram of the ultraviolet-visible absorption spectrum in Embodiment 1 as an example to describe calculation of diffraction efficiency in this application. As shown in
Notes: In Embodiments 1 to 30, the ratio of the peak area of the first characteristic absorption peak to the peak area of the second characteristic absorption peak in the infrared spectrum of the holographic polymer material may be controlled by adjusting content of the second-order monomer.
It can be learned from the data in Table 4 that the ratios of the peak area of the first characteristic absorption peak to the peak area of the second characteristic absorption peak included in the diagrams of the infrared spectra of the holographic polymer materials corresponding to Embodiments 1 to 24 range from 1 to 5, diffraction efficiency of the holographic polymer materials is greater than 80%, and transmittances of the holographic polymer materials are greater than 80%. The ratios of the peak area of the first characteristic absorption peak to the peak area of the second characteristic absorption peak included in the diagrams of the infrared spectra of the holographic polymer materials corresponding to Embodiments 25 to 30 range from 0.3 to 1, and diffraction efficiency or transmittances of the holographic polymer materials are low.
Based on a same technical concept, an embodiment of this application further provides a display device, obtained by using the holographic recording medium described in the foregoing embodiments through a photopolymerization reaction, or including the holographic polymer material described in the foregoing embodiments. The display device is, for example, a head up display (head up display, HUD) device.
Based on a same technical concept, an embodiment of this application further provides a storage device, obtained by using the holographic recording medium described in the foregoing embodiments through a photopolymerization reaction, or including the holographic polymer material described in the foregoing embodiments. The storage device may be, for example, a holographic memory.
Based on a same technical concept, an embodiment of this application further provides an anti-counterfeiting label, obtained by using the holographic recording medium described in the foregoing embodiments through a photopolymerization reaction, or including the holographic polymer material described in the foregoing embodiments.
It should be noted that in this application, unless otherwise specified, all implementations and preferred implementation methods mentioned in this specification may be combined with each other to form a new technical solution. In this application, unless otherwise specified, all technical features and preferred features mentioned in this specification may be combined with each other to form a new technical solution. In this application, unless otherwise specified, the percentage (%) or part is a weight percentage or a weight part relative to the composition. In this application, unless otherwise specified, the involved components or preferred components thereof may be combined with each other to form a new technical solution. In this application, unless otherwise specified, a value range “a to b” indicates an abbreviated representation of any real number combination between a and b, and includes a and b, where both a and b are real numbers. For example, a value range “1 to 5” indicates that all real numbers from “1 to 5” are listed in this specification, and “1 to 5” is merely an abbreviated representation of a combination of these values. The “range” disclosed in this application is in a form of a lower limit and an upper limit, and may be one or more lower limits and one or more upper limits. In this application, unless otherwise specified, reactions or operation steps may be performed in sequence, or may not be performed in sequence. Optionally, reaction methods in this specification are performed in sequence.
The foregoing descriptions are merely specific implementations of this application, but are not intended to limit the protection scope of this application. Any variation or replacement readily figured out by a person skilled in the art within the technical scope disclosed in this application shall fall within the protection scope of this application. Therefore, the protection scope of this application shall be subject to the protection scope of the claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202110563230.9 | May 2021 | CN | national |
This application is a continuation of International Application No. PCT/CN2022/085089, filed on Apr. 2, 2022, which claims priority to Chinese Patent Application No. 202110563230.9, filed on May 24, 2021. The disclosures of the aforementioned applications are hereby incorporated by reference in their entireties.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/CN2022/085089 | Apr 2022 | US |
| Child | 18518135 | US |
