RU2747130C1 - Liquid composition for photopolymerizable film for optical recording, composition and production method - Google Patents

Abstract

FIELD: photosensitive recording media.SUBSTANCE: invention relates to the field of organic photosensitive recording media and relates to a liquid composition for a photopolymerizable film for optical recording, which forms an image by modulating the refractive index during exposure to activating radiation with a wavelength in the range of 500-550 nm. The liquid composition includes a mixture of liquid acrylic monomers, diacrylates, sulfide nanoparticles and a photoinitiator of polymerization. Sulfides are nanoparticles of arsenic sulfides in an amount of 1 to 10 wt%, preliminarily obtained by dissolving AS2S3 glass or its non-stoichiometric derivatives. The liquid acrylic monomer is contained in two types, the first of which is in the amount of 10 to 15 wt% and is 2-phenoxyethyl acrylate, the second liquid acrylic monomer is in the amount of 15 to 20 wt% and is 2- (dimethylamino) ethyl acrylate. Diacrylates are present in amounts from 55 to 60% by weight and are diurethane dimethacrylate in the form of a mixture of isomers. The photoinitiator of polymerization Irgacure784 is contained in an amount of from 3 to 6 wt%.EFFECT: technical result consists in increasing the refractive index and decreasing the thickness of the resulting film.3 cl, 2 tbl

Description

The inventions relate to organic photosensitive recording media, namely to compositions for obtaining photopolymerizable films for optical recording of photonic structures (holograms) and methods for their preparation. The proposed photopolymerizable film forms an image by changing the refractive index and surface relief upon exposure to activating radiation with a wavelength in the range from 500 to 550 nm. The refractive index of the above film is increased as a result of the presence of As ₂ S ₃ nanoparticles included in its composition.

Known compositions for photopolymerizable films and methods of obtaining photopolymer films for recording holograms. They can be divided into three main categories: liquid coatings containing a photoinitiator and monomers, dry film formulations containing a photoinitiator system, a monomer and a binder polymer component that forms a film, and dry film formulations containing a crosslinking polymer and a photosensitizer or initiator.

Known composition for a photopolymerizable film, a method for its production and a method for making a photopolymerizable film for recording holograms (RF patent No. 2325680, priority date 04/22/2004, publ. 05/27/2008, IPC G03F 7/031, G03F 7/028, G03F 7/033 , G02B 5/32). The composition of the photopolymerizable recording medium consists of an unsaturated compound capable of radical ion photopolymerization; a system providing photoactivation by radiation in the spectral range of 400-600 nm and consisting of a photochromic compound and a co-initiator. The composition contains a photochromic compound with a long lifetime of the photoinduced form or a thermally irreversible photochromic compound and, optionally, a polymeric binder, a plasticizer and a non-polymerizable organic liquid with a high refractive index.

The method of obtaining the composition consists in preparing a solution of a solid photochromic compound FNH 1 in N-vinylpyrrolidone and adding to the resulting solution a mixture of polymerizable compounds (OKM-2 and TATMT), as well as a co-initiator DMEA. The resulting solution was thoroughly mixed and evacuated.

A method of obtaining a photopolymerizable film includes applying the prepared solution to a Mylar film with a spacer of a predetermined thickness and covering it on top with a second Mylar film. As a result, a triplex material was obtained.

The disadvantages of the known analogue composition for a photopolymerizable film: the presence of a plasticizer and a non-polymerizable organic liquid with a high refractive index predetermine diffusion after recording and degradation of the recorded hologram, especially at elevated temperatures. The use of a complex photoactivation system, consisting of a photochromic compound and a co-initiator, and the presence of a polymer binder complicates the technological chain. Insufficient modulation of the refractive index due to the small difference between the index of the moved component and the matrix.

A known composition for a photopolymerizable film, a method for producing a composition (RF patent No. 2331095, priority date 12/08/2006, publ. 08/10/2008, IPC G03F 7/028, G03F 7/033).

The composition for a photopolymerizable film is a liquid acrylic monomer with one (meta) acrylic group; bifunctional acrylic oligomer with two (meta) acrylic groups; thermoplastic linear polymer; photoinitiator of polymerization when activating the irradiation of light with a wavelength of 350-400 nm; low boiling solvent; a solvent that dissolves the thermoplastic polymer binder.

The disadvantage of the analogue composition is the presence of a thermoplastic linear polymer, which complicates the technological chain and lowers the thermal stability of the finished hologram.

The method for preparing the composition includes preparing solutions by adding components to a solvent and then stirring with a magnetic stirrer until complete dissolution.

A method of obtaining a dry photopolymerizable film consists in applying a composite from a low-boiling solvent using a centrifuge. The solutions are applied to a glass substrate at a substrate rotation speed of 8 rpm using an applicator and laminator. Then the film is dried under foil at room temperature and finally at 70 ° C.

The disadvantage of the method for producing an analogue is the mandatory use of complex equipment (centrifuge using an applicator and a laminating machine).

As a prototype, a liquid composition for a photopolymerizable film for recording a hologram, a method for obtaining a composition, a method for producing the above film (RF patent No. 2541521, priority date 05/23/2013, published on 11/27/2014, IPC G03F 7/028, G03F 7/027, G03F 7/033, G03F 7/07, В82В 1/00).

The composition for a photopolymerizable film is a mixture of 30 to 69.45 wt. % of liquid acrylic monomer having at least one acidic group COOH and related to carboxylic acids and from 30 to 69.45 wt. % oligomers of mono - and di - acrylates, from 0.5 to 25 wt. % of one of the types of nanoparticles ZnO, SiO ₂ , TiO ₂ , ZnS, CdS coated or not coated with organic shells and having a size from 2 to 30 nm, as well as from 0.05 to 5 wt. % photopolymerization initiator, which is 2,2-dimethoxy-2-phenylacetophenone or bis- (5-2,4-cyclopentadien-1-yl) bis- [2,6-difluoro-3- (1H-pyrrole-1 -yl) phenyl] titanium, initiating upon exposure to activating radiation with a wavelength of 325-550 nm.

The disadvantage of the composition of the prototype is the lack of nonlinear optical properties and reversible photosensitive properties.

The method for preparing the composition includes preparing a mixture by mixing and heating a mixture of the above acrylates for 2 hours at t = 90 ° C, then the specified amount of nanoparticles from the specified list is introduced in portions into the heated liquid composition until a transparent solution is obtained, after complete dispersion of the nanoparticles in the monomer mixture of the liquid composition, constant stirring at t = 90 ° C, a photopolymerization initiator is added, and the liquid composition is stirred at a temperature of t = 90 ° C, the resulting composition is kept in a thermostat at t = 40 ° C.

The disadvantage of this method is the use of an elevated temperature, as a result of which an uncontrolled change in the composition of the monomers is possible, which worsens the repeatability of the properties of the composition.

A method of obtaining a photopolymerizable film for recording a hologram includes applying the above liquid composition in the form of a drop to a polyester film, covering it with another similar film and rolling it between rollers at a temperature of +20 to + 60 ° C.

The disadvantage of obtaining a photopolymerizable film for recording holograms is the need to use rollers and increase the temperature, which also leads to an uncontrolled change in the composition, which worsens the repeatability of the properties of the above film.

The presented group of inventions solves the problem of imparting nonlinear optical properties and reversible photosensitive properties to a photopolymerizable film for optical recording of photonic structures (active light-induced three-dimensional gratings - holograms) while maintaining high values of modulation of the refractive index Δn, diffraction efficiency and their stability over time.

The problem is solved by the fact that the liquid composition for a photopolymerizable film for optical recording, which forms an image by modulating the refractive index during exposure to activating radiation with a wavelength in the range of 500-550 nm, includes a mixture of liquid acrylic monomers, the first of which is in the amount from 10 to 15 wt. % and has at least one phenyl ring in the side chain (2-phenoxyethyl acrylate, 40,833-6 ALDRICH, PEA), the second liquid acrylic monomer is in an amount from 15 to 20 wt.% and has at least one secondary amino group (2- (dimethylamino) ethyl acrylate, 330957 ALDRICH, AmAc), also contains from 55 to 60 wt% diacrylates with two methacrylic and at least two urethane groups (diurethane dimethacrylate, isomer mixture, 436909 Aldrich, UDMA), synthesized nanoparticles in the form of nanoparticles of arsenic trisulfide (or its nonstoichiometric derivatives) in an amount from 1 to 10 wt.% and the polymerization initiator - bis (cyclopentadienyl) bis [2,6-difluoro-3- (1-pyrryl) phenyl] titanium (Irg784) in an amount from 3 to 6 wt.%.

The use of a photopolymerizable monomer composition filled with As ₂ S ₃ nanoparticles ensures the preservation of both high values of the modulation of the refractive index Δn, respectively, and high values of the diffraction efficiency of active light-induced three-dimensional gratings, and the stability of values over time. As ₂ S ₃ nanoparticles have a high linear refractive index; therefore, their photoinduced movement during optical recording of gratings leads to a significant value of Δn due to a significant difference in the refractive index of nanoparticles and the matrix, and polymerization leads to fixation of the recorded hologram. _{The presence of As 2} S ₃ nanoparticles in the liquid composition, possessing reversible photosensitive properties and nonlinear optical properties, and the retention of these properties during optical recording, makes it possible to write diffraction gratings with these properties.

The method of obtaining the above-mentioned liquid composition for obtaining a photopolymerizable film includes dissolving in the dark without access to oxygen at room temperature As ₂ S ₃ glass (0.1 g) in a mixture of diethylamine (3 ml) with low molecular weight hydroxylamines (4 wt%), then into the resulting solution while stirring, the specified amount of the above monomers (UDMA; PEA; AmAc) is introduced in turn, continuing stirring for 5 hours, then the specified amount of the photopolymerization initiator is added to the solution and stirred for 1 hour, then the composition is kept at a temperature of 35 ° C for at least 30 days, every day for 4 hours. The readiness of the composition is determined by the fact that a drop of the finished composition has such a viscosity that, when placed on a glass substrate and covered with a polyester film, it does not spread over the entire surface, but forms a circle upon activating radiation. The resulting composition is kept in the dark at 25 ° C.

A method of obtaining a photopolymerizable film for recording a hologram includes applying the above liquid composition in the form of a drop onto a substrate, covering it with a polyester film. The presence of spicers of a certain thickness allows you to control the thickness. Further, under the press, a film of the composition with a thickness corresponding to the spicers is obtained.

The essence of the claimed inventions is explained as follows.

As a result of the studies carried out, the main factors influencing the optical and other important operational properties of the film have been established.

The first factor is the chemical structure of the monomeric components. A necessary condition preventing the aggregation of arsenic sulfide nanoparticles is the presence of amino groups and a phenyl ring in the monomeric components of the liquid composition. These groups modify the surface of arsenic sulfide nanoparticles by forming donor-acceptor bonds.

The second factor is the presence of low molecular weight hydroxylamines, which, being a modifier of the surface of nanoparticles, provide the possibility of polymerization.

The third factor is the method of obtaining nanoparticles of arsenic sulfide obtained by dissolving in diethylamine together with hydroxylamine, provides the possibility of polymerization processes and introduces reversible photosensitive properties and nonlinear optical properties into the nanocomposite.

The fourth factor is the use of a composition of the above monomers and As ₂ S ₃ nanoparticles obtained by this method, which have a high linear refractive index and have a significant difference with the refractive index of the polymer matrix, guarantee significant modulation of the refractive index and diffraction efficiency of gratings, as well as stability during time.

The fifth factor that affects the quality of the film is the initiator and the method of initiating three-dimensional radical polymerization of the components, which determines the rate of initiation, the concentration of free radicals, and the rate constants of the polymerization process.

To solve this problem, it is necessary to synthesize a nanocomposite suitable for obtaining a photopolymerizable film, create a homogeneous composition of the above-mentioned acrylic components and nanoparticles, select a photoinitiator for radical polymerization of the above-mentioned monomer components when exposed to activating radiation with a wavelength of 500-550 nm.

To achieve the required properties of the aforementioned photopolymerizable nanocomposite film, a composition of polymerizable components, nanoparticles, nanoparticle modifier, photoinitiator of polymerization is used. In general, the composition consists of:

- mixtures of monomers,

- nanoparticles As ₂ S ₃ ,

- nanoparticle modifier

- a photopolymerization initiator.

A mixture of monomers acts as a matrix in which nanoparticles are uniformly distributed and stabilized. The amino groups diurethane dimethacrylate monomers (UDMA) and 2- (dimethylamino) ethyl acrylate (AmAc), the phenyl ring of the 2-phenoxyethyl acrylate (PEA) monomer actively interact with As2S3 nanoparticles and modify their surface in such a way that improves the compatibility of the organic nanoparticles with the acrylic nanoparticles. The presence of UDMA monomer in solution also allows the formation of a polymer network, which contributes to the stability of the lattices over time. Obtaining As ₂ S ₃ nanoparticles obtained by dissolving in diethylamine with hydroxylamine, the latter acting as a modifier of nanoparticles, allows photoinduced polymerization and optical recording, respectively. The refractive index of nanoparticles significantly differs from the refractive index of the monomeric matrix, which determines the significant modulation of the refractive index during the redistribution of nanoparticles. It is important that all monomers are compatible with diethylamine and hydroxylamine and As ₂ S ₃ nanoparticles.

The following monomers were used to prepare the compositions:

1.) Diurethane dimethacrylate, isomer mixture (436909 ALDRICH, UDMA)

2.) 2-phenoxyethyl acrylate (40.833-6 ALDRICH, PEA)

3.) 2- (dimethylamino) ethyl acrylate (330957 ALDRICH. AmAc)

Studies have shown that bis (cyclopentadienyl) bis [2,6-difluoro-3- (1-pyrryl) phenyl] titanium (Irgacure784) should be used as a polymerization initiator.

To prepare the compositions, arsenic sulfide nanoparticles were used, obtained by dissolution in diethylamine with hydroxylamine

An example of a method for preparing a liquid composition.

Main components - 9.25 wt. % As2S3 nanoparticles, 57.25 wt. % UDMA, 11.25 wt. % PEA, 17.25 wt.% AmAc, 5 wt. % Irgacure784, 0.4 wt. % hydroxylamino chloride.

At room temperature, first, glass As ₂ S ₃ (0.1 g) was dissolved in a mixture of diethylamine (3 ml) with low molecular weight hydroxylamines (4 wt%) in the dark without access to oxygen, then the indicated amount of the above monomers was introduced into the resulting solution with stirring. (UDMA; PEA; AmAc), continuing stirring for 5 hours, then the specified amount of photopolymerization initiator was added to the solution and stirred for 1 hour, then the composition was kept at 35 ° C for 30 days, stirred every day for 4 hours. The readiness of the composition was determined by the fact that a drop of the finished composition had such a viscosity that, when placed on a substrate and covered with a polyester film, it did not spread over the surface, but formed a circle when irradiated with light with a wavelength of 532 nm.

An example of obtaining a photopolymerizable film.

A method of obtaining a photopolymerizable film for optical recording of a hologram includes applying the above liquid composition in the form of a drop onto a substrate, covering it with a polyester film. Next, a film of the composition with a thickness corresponding to the spicers is obtained under a press.

Description of optical recording of active photoinduced three-dimensional gratings on the developed liquid composition.

The proposed liquid composition, placed between glass and polyester, was exposed to DPSS laser radiation with a wavelength of 532 nm, an output power of 35 mW at an energy density of 3⋅10 ^-2 J / cm ² , at angles between interfering beams of 30-45 °, exposure durations 15 -30 min, layer thicknesses 35 ± 5 microns. Transmitting holograms were obtained, the diffraction efficiency was determined by the ratio of the radiation intensity in the first diffraction order to the intensity of the incident radiation at a wavelength of 633 nm. The following examples show the results of optical recording carried out on the developed liquid composition.

1.) Example 1.

The materials were exposed for 20 min, the diffraction efficiency was determined after exposure

2.) Example 2.

The materials were exposed for 35 min, the diffraction efficiency was determined after exposure.

Table 2 shows the maximum values of the diffraction efficiency for transmission holograms obtained according to paragraphs. 1.2.

Thus, the claimed liquid composition of a photopolymerizable film for optical recording of photonic structures (gratings), a method for obtaining this composition, as well as a method for obtaining the above film provide optical recording of diffraction gratings (holograms), while processing after exposure is not required, high values of diffraction efficiency - up to 40% with a film thickness of 35 ± 5 microns.

The obtained photopolymerizable film retains the nonlinear optical properties inherent in arsenic trisulfide, and the reversibility of optical transmission is also observed, namely, when the films are irradiated with a wavelength in the range from 500 to 550 nm, the fundamental edge of optical absorption shifts towards higher frequencies, and upon subsequent heating at 150 ° С for 1 hour there is a shift towards lower frequencies. The moisture resistance of the proposed liquid composition is significantly higher than that of known polymers for optical recording due to the absence of hydrophilic components in the composition and the presence of inorganic nanoparticles in the polymer shell due to the formation of donor-acceptor bonds with functional groups of monomers.

Claims (3)

1. Liquid composition for a photopolymerizable film for optical recording, which forms an image by modulating the refractive index upon exposure to activating radiation with a wavelength in the range of 500-550 nm, including a mixture of liquid acrylic monomers, diacrylates, sulfide nanoparticles and a photoinitiator of polymerization in the form bis (cyclopentadienyl) bis [2,6-difluoro-3- (1-pyrryl) phenyl] titanium (Irgacure784), characterized in that the sulfides are preliminarily obtained by dissolving AS ₂ S ₃ glass or its non-stoichiometric derivatives, nanoparticles of arsenic sulfides in an amount from 1 to 10 wt.%, the liquid acrylic monomer is contained in two types, the first of which is in the amount of 10 to 15 wt.% and is 2-phenoxyethyl acrylate, PEA, 40.833-6 ALDRICH, the second liquid acrylic monomer is in the amount from 15 to 20 wt.% and represents 2- (dimethylamino) ethyl acrylate, АmАс, 330957 ALDRICH, diacrylates are contained in amounts from 55 to 60 wt.% and are diurethane dimethacrylate in the form of a mixture of isomers, 436909 Aldrich, UDMA, and the photoinitiator of polymerization - Irgacure784 - is contained in an amount from 3 to 6 wt.%. 2. A method of obtaining a liquid composition for a photopolymerizable film for optical recording according to claim 1, comprising mixing the above components, characterized in that first, to obtain nanoparticles of arsenic sulfide at room temperature in the dark without access to oxygen, glass AS ₂ S ₃ (0, 1 g) in a mixture of diethylamine (3 ml) in the presence of low molecular weight hydroxylamines (0.4 wt%), then the specified amount of the above monomers (UDMA; PEA; АmАс) is alternately introduced into the resulting solution with stirring, continuing stirring for 5 hours, then the specified amount of Irgacure784 photopolymerization initiator is added to the solution and stirred for 1 hour, then, to remove diethylamine, the composition is kept at a temperature of 35 ° C for at least 30 days, stirring every day for 4 hours, a drop of the composition is placed on a substrate, covered with a polyester film and in the absence of spreading when it is irradiated for 20 min with light from the range the zone of activating radiation makes a conclusion about the readiness of the composition. 3. A method of obtaining a photopolymerizable film for optical recording, comprising applying the finished liquid composition according to claim 1 in the form of a drop onto a substrate, covering it with a polyester film, characterized in that the liquid composition is applied at room temperature to the substrate and pressed with a press to a thickness corresponding to the spicers ...