KR20240064240A - Initiator compound used for recording optical information, photo polymerization initiator system and composition comprising the same - Google Patents

Abstract

This application relates to (co)initiator compounds used in optical information recording, initiator systems and compositions containing them.

Description

Initiator compound used for recording optical information, photo polymerization initiator system and composition comprising the same}

This application relates to initiator compounds, initiator systems and compositions containing them. Specifically, the present application relates to initiator compounds used in optical information recording and initiator systems and compositions containing the same.

A hologram recording medium records information by changing the refractive index in the holographic recording layer through an exposure process, and reads the difference in the recorded refractive index to reproduce the information.

In this regard, photopolymer compositions can be used for hologram production. Photopolymers can easily store optical interference patterns as holograms by photopolymerization of photoreactive monomers. Therefore, photopolymers are used in smart devices such as mobile devices, parts of wearable displays, automotive products (e.g., head up display), holographic fingerprint recognition systems, optical lenses, mirrors, deflecting mirrors, filters, diffusion screens, diffraction members, and light guides. It can be used in a variety of fields, including holographic optical elements that function as a screen, waveguide, projection screen, and/or mask, media and light diffusion plates in optical memory systems, optical wavelength splitters, and reflective and transmissive color filters.

Specifically, the photopolymer composition for producing a hologram includes a polymer matrix, a photoreactive monomer, and a photoinitiator system. Then, the photopolymer prepared from this composition is irradiated with laser interference light to induce local photopolymerization of the monomer.

Through this local photopolymerization process, refractive index modulation occurs, and a diffraction grating is created through this refractive index modulation. The refractive index modulation value (△n) is affected by the thickness of the photopolymer layer and the diffraction efficiency (DE), and the angular selectivity becomes wider as the thickness becomes thinner.

Recently, there has been a growing demand for the development of materials that can maintain high diffraction efficiency and stable holograms, and various attempts have been made to manufacture hologram recording media that have a small thickness but have high diffraction efficiency and a high refractive index modulation value.

Meanwhile, the holographic recording medium needs to exhibit excellent stability over time even before recording optical information, thereby exhibiting the originally intended optical recording characteristics. However, holographic recording media have limitations in that they do not exhibit originally intended optical recording characteristics as the photoinitiator system reacts during storage.

One object of the present application is to provide a compound that is used in a photopolymerizable composition and contains a cation and an anion having a predetermined structure.

Another object of the present application is to provide a compound included in an initiator system that can provide excellent stability over time.

Another object of the present application is to provide an initiator system that can provide excellent stability over time.

Another object of the present application is to provide a composition comprising an initiator system that can provide excellent stability over time.

Another object of the present application is to provide a hologram recording medium manufactured using the above compound, initiator system, and composition.

The above objects and other objects of the present application can all be solved by the present application described in detail below.

According to an embodiment of the present application, an initiator compound, initiator system, and composition for photopolymerization used in producing a hologram recording medium are provided. Additionally, according to another embodiment of the present application, a hologram recording medium that satisfies predetermined characteristics can be provided.

Hereinafter, specific examples of the invention of this application will be described in more detail.

In one example related to this application, this application relates to initiator compounds for photopolymerization. In the applications described below, the compound can be used as a type of radical initiator.

The compounds of the present application can be used in photopolymerizable compositions. Specifically, the photopolymerizable composition may include a polymer matrix, a photoreactive monomer, and a photoinitiator system, and the compound may be included in the photoinitiator system. In addition, the compound is activated by light irradiation to cause photopolymerization of the photoreactive monomer dispersed in the polymer matrix, and can be used to record optical information.

For example, a hologram recording medium includes a photopolymer film on which optical information is recorded, and the photopolymer may be manufactured by irradiating object light and reference light to a coating solution (or coating composition) for forming a photopolymer. In the area where object light and reference light destructively interfere, the photoinitiator system is in an inactive state, so photopolymerization of the photoreactive monomer does not occur, and in the constructive interference area, photopolymerization of the photoreactive monomer occurs due to the activated photoinitiator system. As the photoreactive monomer is continuously consumed in the constructive interference area, a concentration difference occurs between the photoreactive monomer in the destructive interference area and the constructive interference area. As a result, the photoreactive monomer in the destructive interference region diffuses into the constructive interference region. Since the photoreactive monomer and the photopolymer formed therefrom have a high refractive index compared to the polymer matrix, spatial changes in refractive index occur in the photopolymer, and a lattice is created due to the spatial refractive index modulation occurring in the photopolymer. This grating surface serves as a reflective surface that reflects incident light by the difference in refractive index, and when light of the same wavelength is incident when recording in the direction of the reference light after recording the hologram, the Bragg condition is satisfied and the light diffracts in the direction of the original object light. Holographic optical information can be reproduced.

The initiator compound of the present application contains a borate anion with three aryl groups introduced into the borate center, and serves as a photoinitiator. Since at least one halogen substituent is introduced into the aryl group of the borate compound to adjust the energy level, it can sufficiently perform the role of a radical initiator under photopolymerization conditions.

In an embodiment of the present application, the compound is an anion represented by Formula 1 below; and a cation represented by Formula 2 below, and is activated by light irradiation to cause photopolymerization of the photoreactive monomer dispersed in the polymer matrix, and is used to record optical information.

[Formula 1]

In Formula 1,

R ¹⁰² is each independently hydrogen, an alkyl group or halogen, and at least one of R ¹⁰² is halogen,

R ¹⁰³ is each independently hydrogen, an alkyl group, or halogen, but when the adjacent R ¹⁰² is hydrogen or an alkyl group, it is halogen,

R is an alkyl group having 1 to 24 carbon atoms.

Unless specifically defined otherwise in the specification, the specific type of halogen is not particularly limited and may be selected from, for example, F, Cl, Br, or I.

Additionally, unless specifically defined otherwise in the specification, the “alkyl group” may be a straight-chain, branched-chain, or cyclic alkyl group. The carbon number of the alkyl group may be, for example, 1 to 24, 1 to 16, 1 to 8, or 1 to 4. By way of non-limiting example, alkyl groups herein include methyl, ethyl, propyl (e.g., n-propyl, isopropyl, etc.), butyl (e.g., n-butyl, isobutyl, tert-butyl, sec-butyl, cyclobutyl, etc.) , pentyl (e.g. n-pentyl, isopentyl, neopentyl, tert-pentyl, 1,1-dimethyl-propyl, 1-ethyl-propyl, 1-methyl-butyl, cyclopentyl, etc.), hexyl (e.g. n- Hexyl, 1-methylpentyl, 2-methylpentyl, 4-methylpentyl, 3,3-dimethylbutyl, 1-ethyl-butyl, 2-ethylbutyl, cyclopentylmethyl, cyclohexyl, etc.), heptyl (e.g., n- Heptyl, 1-methylhexyl, 4-methylhexyl, 5-methylhexyl, cyclohexylmethyl, etc.), octyl (e.g., n-octyl, tert-octyl, 1-methylheptyl, 2-ethylhexyl, 2-propylpentyl, etc. ), nonyl (eg, n-nonyl, 2,2-dimethylheptyl, etc.).

In one example, R in Formula 1 may be an alkyl group of 10 or less. Specifically, R in Formula 1 may be an alkyl group having 4 to 8 carbon atoms or 4 to 6 carbon atoms, and in this case, excellent stability can be ensured.

In one example, among the three aromatic rings bonded to the borate of Formula 1, at least two aromatic rings may be substituted with halogen. For example, two of R ¹⁰² in Formula 1 may be halogen. In this case, R ¹⁰³ may each independently be hydrogen or an alkyl group.

In one example, all three aromatic rings bonded to the borate of Formula 1 may be substituted with halogen. For example, three of R ¹⁰² in Formula 1 may be halogen. In this case, R ¹⁰³ may each independently be hydrogen or an alkyl group.

[Formula 2]

NY ¹ Y ² Y ³ Y ⁴

In Formula 2, two substituents of Y ¹ to Y ⁴ may or may not be connected to each other to form an aliphatic ring having 4 to 10 carbon atoms,

Y ¹ to Y ⁴ that do not form an aliphatic ring are each independently an alkyl group with 1 to 40 carbon atoms, an aryl group with 6 to 30 carbon atoms, an arylalkyl group with 6 to 40 carbon atoms, or an alkyl group with 2 to 40 carbon atoms linked through an ester bond. (For example, -CH ₂ CH ₂ -O-CO-CH ₂ CH ₂ CH ₃ , etc.),

It is excluded that Y ¹ to Y ⁴ are all methyl groups or that two or more substituents are alkyl groups having 16 or more carbon atoms.

In Formula 2, if Y ¹ to Y ⁴ are all methyl groups, or two or more substituents are alkyl groups having 16 or more carbon atoms, the electron donor may not dissolve well in the photopolymer composition and may not exhibit the desired optical recording characteristics.

In one example, two of the substituents Y ¹ to Y ⁴ may be connected to each other to form piperidine or pyrrolidine. As a result of experimental confirmation, when two of the substituents Y ¹ to Y ⁴ are connected to each other to form piperidine or pyrrolidine, for example, when Y ¹ to Y ⁴ are all alkyl groups, the solubility is higher than when used. It is advantageous to secure.

Among Y ¹ to Y ⁴ , the substituents that do not form an aliphatic ring may each independently be a straight-chain alkyl group having 1 to 32 carbon atoms, a phenyl group, a benzyl group, or -CH ₂ CH ₂ -O-CO-CH ₂ CH ₂ CH ₃ . More specifically, the substituents that do not form an aliphatic ring among Y ¹ to Y ⁴ may each independently be, for example, a methyl group, a butyl group, a hexadecyl group, a hentriacontyl group, a phenyl group, or a benzyl group. . According to a specific example of the present application, when at least one substituent among Y ¹ to Y ⁴ that does not form an aliphatic ring is or includes an alkyl group having 10 or more carbon atoms, such as a hexadecyl group, the structural stability of the compound is excellent.

In one example, in Formula 2, at least one of Y ¹ to Y ⁴ may be an aryl group, more specifically, a benzyl group. As a result of experimental confirmation, when at least one of Y ¹ to Y ⁴ is an aryl group, for example, it may be advantageous to secure higher solubility than when all of Y ¹ to Y ⁴ are alkyl groups.

Although not particularly limited, the nitrogen-containing cation usable as the cation of Formula 2 may be, for example, hexadecyl dimethyl benzyl ammonium cation or hexadecyl benzyl pyrrolidinium.

In a specific example of the present application related to the use of the compound, the polymer matrix may be a polymer matrix formed by crosslinking a siloxane-based polymer containing a silane functional group and a (meth)acrylic-based polyol. Specific examples are described in the description of the composition described later.

In a specific example of the present application related to the use of the compound, the photo-reactive monomer may have one or more photo-reactive groups selected from a (meth)acryloyl group, a vinyl group, and a thiol group. Specific examples are described in the description of the composition described later.

In another example, the present application relates to a photopolymerization initiator system comprising the above-described compound (comprising an anion of Formula 1 and a cation of Formula 2).

The photo polymerization initiator system further includes a light-sensitive dye in addition to a compound (containing an anion of Formula 1 and a cation of Formula 2), and is activated by light irradiation to cause photopolymerization of the photo-reactive monomer dispersed in the polymer matrix, , can be used to record optical information.

The description of the compound (electron donor) containing the anion of Chemical Formula 1 and the cation of Chemical Formula 2 included in the photopolymerization initiator system is the same as the above, and thus is omitted.

The photosensitive dye included in the photopolymerization initiator system is not particularly limited, and those mentioned in the description of the composition described later or those having the characteristics described later may be used.

In a specific example of the present application, the initiator system uses a photosensitive dye described later as an electron donor and a specific reaction energy (i.e., a compound containing an anion of Formula 1 and a cation of Formula 2) to produce photopolymerized photopolymerization. It can provide excellent stability over time to polymer or holographic recording media.

Specifically, the electron donor (a compound containing an anion of Formula 1 and a cation of Formula 2) reacts with a photosensitive dye excited to a triplet state by light irradiation as shown in Scheme 1 below and participates in the photopolymerization initiation reaction. .

[Scheme 1]

At this time, if an electron donor with a reaction energy of -25 to 0 kJ/mol with a photosensitive dye excited in a triplet state is used, the reaction does not start even at room temperature or high temperature before light irradiation, showing excellent stability over time and when light is irradiated. A sensitive photo-initiated reaction occurs, resulting in excellent optical recording properties.

More specifically, the electron donor has a reaction energy with a photosensitive dye excited in a triplet state of - 25 kJ/mol or more, - 20 kJ/mol or more, - 15 kJ/mol or more, - 14 kJ/mol or more, - 13 kJ/mol or more, - 12 kJ/mol or more, - 11 kJ/mol or more, - 10 kJ/mol or more, - 9 kJ/mol or more, or - 8.5 kJ/mol or more and 0 kJ/mol or less, - 3 kJ It may be /mol or less or -5 kJ/mol or less. For the method of measuring the reaction energy, refer to the measurement method described in detail in the test example described later.

In one example, the photo polymerization initiator system may further include an electron acceptor. The electron acceptor may include, for example, one or more selected from onium salt compounds and triazine compounds, and those mentioned in the description of the composition described later may be used. The electron acceptor receives electrons during the redox reaction of the photoinitiator system, and when an electron acceptor is included, the total energy E2 of the photoinitiator system reaction increases toward a negative value. However, as a result of the present inventors' research, even if the total energy of the photoinitiator system reaction changes due to the inclusion of the electron acceptor, excellent stability over time can be secured only when the reaction energy of the photosensitive dye and the electron donor is within the above-mentioned range.

The electron acceptor included in the photopolymerization initiator system is not particularly limited, and those mentioned in the description of the composition described later or those having the characteristics described later may be used.

In another example relating to this application, this application relates to a photopolymerizable composition comprising a compound (comprising an anion of Formula 1 and a cation of Formula 2) described above. The composition can be used to produce a photopolymer, specifically a photopolymer layer of a holographic recording medium, which will be described later.

In one example, the composition may include a polymer matrix, a photoreactive monomer, and a photoinitiator system. Alternatively, the composition may include a polymer matrix; and photopolymers obtained from photoreactive monomers and photoinitiator systems. Alternatively, the composition may include all of a polymer matrix photoreactive monomer, a photoinitiator system, and a photopolymer.

In one example, the polymer matrix may be a polymer matrix formed by crosslinking a siloxane-based polymer containing a silane functional group (Si-H) and a (meth)acrylic polyol. Specifically, the polymer matrix is crosslinked (meth)acrylic polyol with a siloxane-based polymer containing a silane functional group. More specifically, the hydroxy group of the (meth)acrylic polyol can form a crosslink with the silane functional group of the siloxane-based polymer through a hydrosilylation reaction. The hydrosilylation reaction can proceed rapidly even at relatively low temperatures (for example, around 60°C) under a Pt-based catalyst. Therefore, the photopolymer layer can improve the manufacturing efficiency and productivity of the hologram recording medium by employing a polymer matrix that can be quickly crosslinked even at a relatively low temperature as a support.

The polymer matrix can increase the mobility of components (eg, photoreactive monomers or plasticizers) included in the photopolymer due to the flexible main chain of the siloxane-based polymer. In addition, siloxane bonding with excellent heat resistance and moisture heat resistance properties can facilitate securing the reliability of the photopolymer on which optical information is recorded and the hologram recording medium containing the same.

The polymer matrix may have a relatively low refractive index, thereby serving to increase the refractive index modulation of the photopolymer or photopolymer layer. For example, the upper limit of the refractive index of the polymer matrix may be 1.53 or less, 1.52 or less, 1.51 or less, 1.50 or less, or 1.49 or less. And, the lower limit of the refractive index of the polymer matrix may be, for example, 1.40 or more, 1.41 or more, 1.42 or more, 1.43 or more, 1.44 or more, 1.45 or more, or 1.46 or more. In this specification, “refractive index” may be a value measured with an Abbe refractometer at 25°C.

The photopolymer or photopolymer layer includes a polymer matrix formed by crosslinking the siloxane-based polymer containing the above-described silane functional group and (meth)acrylic polyol, but may include a polymer matrix precursor that is not partially crosslinked. At this time, the polymer matrix precursor may mean a siloxane-based polymer, (meth)acrylic-based polyol, and Pt-based catalyst.

For example, the siloxane-based polymer may include a repeating unit represented by Formula 3 below and a terminal group represented by Formula 4 below.

[Formula 3]

In Formula 3 above,

A plurality of R ¹ and R ² are the same or different from each other and are each independently hydrogen, halogen, or an alkyl group having 1 to 10 carbon atoms,

n is an integer from 1 to 10,000,

[Formula 4]

In Formula 4 above,

A plurality of R ¹¹ to R ¹³ are the same or different from each other, and each independently represents hydrogen, halogen, or an alkyl group having 1 to 10 carbon atoms,

At least one of R ¹ , R ² , and R ¹¹ to R ¹³ of at least one of the repeating units represented by Formula 3 and one of the terminal groups represented by Formula 4 is hydrogen.

In Formula 4, -(O)- is bonded through oxygen (O) or directly without oxygen (O) when Si of the terminal group represented by Formula 4 is bonded to the repeating unit represented by Formula 3. It means to do.

In one example, R ¹ , R ² and R ¹¹ to R ¹³ in Formulas 3 and 4 are methyl or hydrogen, and at least two of the plurality of R ¹ , R ² and R ¹¹ to R ¹³ may be hydrogen. . More specifically, the siloxane-based polymer includes compounds in which R ¹ and R ² of Formula 3 are methyl and hydrogen, respectively, and R ¹¹ to R ¹³ of Formula 4 are each independently methyl or hydrogen (for example, a terminal group is trimethyl polymethylhydrosiloxane, which is a silyl group or dimethylhydrosilyl group); Some R ¹ and R ² of Formula 4 are methyl and hydrogen, respectively, the remaining R ¹ and R ² are both methyl, and R ¹¹ to R ¹³ of Formula 4 are each independently methyl or hydrogen (e.g., a terminal compound poly(dimethylsiloxane-co-methylhydrosiloxane) wherein the group is a trimethylsilyl group or a dimethylhydrosilyl group, or R ¹ and R ² of the formula 3 are both methyl, and at least one of R ¹¹ to R ¹³ of the formula 4 is hydrogen; and the remainder are each independently methyl or hydrogen (e.g., polydimethylsiloxane in which either or both of the terminal groups are dimethylhydrosilyl groups).

For example, the siloxane-based compound may have a number average molecular weight (Mn) in the range of 200 to 4,000. Specifically, the lower limit of the number average molecular weight of the siloxane-based polymer may be, for example, 200 or more, 250 or more, 300 or more, or 350 or more, and the upper limit may be, for example, 3,500 or less, 3,000 or less, 2,500 or less, 2,000 or less, It may be 1,500 or less or 1,000 or less. When the number average molecular weight of the siloxane-based polymer satisfies the above range, the siloxane-based polymer volatilizes during the crosslinking process with (meth)acrylic polyol at room temperature or higher, thereby lowering the degree of matrix crosslinking, or the siloxane-based polymer Problems such as poor compatibility with components of other photopolymer layers, such as phase separation with these components, can be prevented. As a result, the hologram recording medium can exhibit excellent optical recording characteristics and thermal stability.

The number average molecular weight refers to the number average molecular weight (unit: g/mol) in terms of polystyrene measured by GPC method. In the process of measuring the number average molecular weight of polystyrene equivalent measured by the GPC method, commonly known analysis devices, detectors such as differential refractive index detectors, and analytical columns can be used, and the commonly applied temperature Conditions, solvent, and flow rate can be applied. Specific examples of the measurement conditions include a temperature of 30° C., tetrahydrofuran solvent, and a flow rate of 1 mL/min.

In one example, the silane functional group (Si-H) equivalent weight of the siloxane-based polymer may be, for example, in the range of 30 to 200 g/equivalent. More specifically, the silane functional group (Si-H) equivalent weight of the siloxane-based polymer is 50 g/equivalent or more, 60 g/equivalent or more, 70 g/equivalent or more, 80 g/equivalent or more, or 90 g/equivalent or more, and is 180 g/equivalent or more. It may be less than g/equivalent or less than 150 g/equivalent.

In this specification, “equivalent of a certain functional group” briefly refers to the number of g equivalents (equivalent weight, also called equivalent weight) expressed in units of g/equivalent, and refers to the molecular weight (weight average) of a molecule or polymer containing the functional group in question. It refers to the value divided by the number of functional groups (molecular weight, number average molecular weight, etc.). Therefore, the smaller the equivalent value, the higher the density of the functional group, and the larger the equivalent value, the smaller the density of the functional group.

When the silane functional group equivalent of the siloxane-based polymer satisfies the above range, the polymer matrix has an appropriate crosslinking density and sufficiently performs the role of a support, and the fluidity of the components included in the photopolymer layer is improved, so that the diffraction gratings generated after recording are improved. Even as time passes without the problem of the boundary collapsing, the initial refractive index modulation value is maintained at an excellent level, thereby minimizing the decrease in recording characteristics for optical information.

In one example, the (meth)acrylic polyol may refer to a polymer in which one or more, specifically, two or more hydroxy groups are bonded to the main chain or side chain of a (meth)acrylate polymer. In this specification, “(meth)acrylic (based)” refers to acrylic (based) and/or methacrylic (based), unless specifically stated otherwise, such as acrylic (based), methacrylic (based), or It is a term that encompasses both acrylic (based) and methacrylic (based) mixture.

The (meth)acrylic polyol is a homopolymer of a (meth)acrylate monomer having a hydroxy group, a copolymer of two or more (meth)acrylate monomers having a hydroxy group, or a (meth)acrylate monomer having a hydroxy group. It may be a copolymer of a monomer and a (meth)acrylate-based monomer that does not have a hydroxy group. In this specification, “copolymer” is a term that encompasses random copolymers, block copolymers, and graft copolymers, unless otherwise specified.

Examples of the (meth)acrylate-based monomer having the hydroxy group include hydroxyalkyl (meth)acrylate or hydroxyaryl (meth)acrylate, and the alkyl is an alkyl having 1 to 30 carbon atoms. , and the aryl may be an aryl having 6 to 30 carbon atoms. In addition, examples of the (meth)acrylate-based monomer that does not have the hydroxy group include alkyl (meth)acrylate-based monomers or aryl (meth)acrylate-based monomers, and the alkyl has 1 to 1 carbon atoms. It is an alkyl of 30, and the aryl may be an aryl of 6 to 30 carbon atoms.

For example, the (meth)acrylic polyol may have a weight average molecular weight (Mw) in the range of 150,000 to 1,000,000. The weight average molecular weight means the weight average molecular weight in terms of polystyrene measured by the GPC method as described above. For example, the lower limit of the weight average molecular weight may be 150,000 or more, 200,000 or more, or 250,000 or more, and the upper limit may be, for example, 900,000 or less, 850,000 or less, 800,000 or less, 750,000 or less, 700,000 or less, 650,000 or less, Below, It may be less than 550,000, less than 500,000, or less than 450,000. When the weight average molecular weight of the (meth)acrylic polyol satisfies the above range, the polymer matrix sufficiently functions as a support, so there is little decrease in the recording characteristics of optical information even with the passage of time, and sufficient flexibility is provided to the polymer matrix. As a result, the mobility of components (eg, photoreactive monomers or plasticizers, etc.) included in the photopolymer can be improved to minimize the decrease in recording characteristics for optical information.

In order to adjust the crosslinking density of the (meth)acrylic polyol by the siloxane-based polymer to a level advantageous for securing the function of a hologram recording medium, the hydroxyl equivalent weight of the (meth)acrylic polyol may be adjusted to an appropriate level.

Specifically, the hydroxyl (-OH) equivalent weight of the (meth)acrylic polyol may be, for example, in the range of 500 to 3,000 g/equivalent. More specifically, the lower limit of the hydroxyl (-OH) equivalent weight of the (meth)acrylic polyol is 600 g/equivalent or more, 700 g/equivalent or more, 800 g/equivalent or more, 900 g/equivalent or more, 1000 g/equivalent or more, 1100 g/equivalent or more. It may be more than g/equivalent, more than 1200 g/equivalent, more than 1300 g/equivalent, more than 1400 g/equivalent, more than 1500 g/equivalent, more than 1600 g/equivalent, more than 1700 g/equivalent, or more than 1750 g/equivalent. And, the upper limit of the hydroxyl group (-OH) equivalent weight of the (meth)acrylic polyol is 2900 g/equivalent or less, 2800 g/equivalent or less, 2700 g/equivalent or less, 2600 g/equivalent or less, 2500 g/equivalent or less, 2400 g/ It may be equivalent or less, 2300 g/equivalent or less, 2200 g/equivalent or less, 2100 g/equivalent or less, 2000 g/equivalent or less, or 1900 g/equivalent or less.

When the hydroxyl (-OH) equivalent of the (meth)acrylic polyol satisfies the above range, the polymer matrix has an appropriate crosslinking density and sufficiently performs the role of a support, and the fluidity of the components included in the photopolymer layer is improved, so that the polymer matrix can be used after recording. The initial refractive index modulation value can be maintained at an excellent level even as time passes without the problem of the interface between the generated diffraction gratings collapsing, thereby minimizing the decrease in recording characteristics for optical information.

For example, the (meth)acrylic polyol may have a glass transition temperature (Tg) in the range of -60 to -10°C. Specifically, the lower limit of the glass transition temperature may be, for example, -55 ℃ or higher, -50 ℃ or higher, -45 ℃ or higher, -40 ℃ or higher, -35 ℃ or higher, -30 ℃ or higher, or -25 ℃ or higher. , the upper limit may be, for example, -15°C or less, -20°C or less, -25°C or less, -30°C or less, or -35°C or less. When the above glass transition temperature range is satisfied, the glass transition temperature can be lowered without significantly lowering the modulus of the polymer matrix, thereby increasing the mobility (liquidity) of other components in the photopolymer layer and improving the moldability of the photopolymer composition. The glass transition temperature can be measured using a known method, for example, DSC (Differential Scanning Calorimetry) or DMA (dynamic mechanical analysis).

The refractive index of the (meth)acrylic polyol may be, for example, 1.40 or more and less than 1.50. Specifically, the lower limit of the refractive index of the (meth)acrylic polyol may be, for example, 1.41 or more, 1.42 or more, 1.43 or more, 1.44 or more, 1.45 or more, or 1.46 or more, and the upper limit may be, for example, 1.49 or less, 1.48 or less, It may be 1.47 or less, 1.46 or less, or 1.45 or less. When the (meth)acrylic polyol has a refractive index in the above-mentioned range, it can contribute to increasing the refractive index modulation. The refractive index of the (meth)acrylic polyol is a theoretical refractive index, using the refractive index of the monomer used to produce (meth)acrylic polyol (value measured using an Abbe refractometer at 25 ℃) and the fraction (molar ratio) of each monomer. It can be calculated as:

The (meth)acrylic polyol and the siloxane polymer are included so that the molar ratio (SiH/OH) of the silane functional group (Si-H) of the siloxane polymer to the hydroxyl group (-OH) of the (meth)acrylic polyol is 1.5 to 4. You can.

The molar ratio of the silane functional group of the siloxane-based polymer to the hydroxyl group of the (meth)acrylic polyol (hereinafter, simply referred to as SiH/OH molar ratio) is the number of moles of functional groups determined from the weight of each polymer and the corresponding functional group equivalent of each polymer. It can be calculated from

Specifically, the silane functional group equivalent of the siloxane-based polymer is the molecular weight (e.g., number average molecular weight) of the siloxane-based polymer divided by the number of silane functional groups per molecule, and the hydroxyl equivalent of the (meth)acrylic polyol is the (meth) It is a value obtained by dividing the molecular weight (e.g., weight average molecular weight) of the acrylic polyol by the number of hydroxy functional groups per molecule. Therefore, the number of moles of silane functional groups can be confirmed by dividing the weight of the siloxane-based polymer by the equivalent weight of the silane functional group of the siloxane-based polymer, and by dividing the weight of the (meth)acrylic polyol by the equivalent weight of the hydroxyl group of the (meth)acrylic polyol, the number of moles of hydroxy groups can be determined. You can check it. More specifically, taking Example 1 described below as an example, dividing the weight (2.6 g) of the siloxane-based polymer used in Example 1 by the silane functional group equivalent of the siloxane-based polymer used in Example 1 (103 g/equivanlent) The number of moles of the silane functional group (0.0252 mol) is calculated, and the weight (22.4 g) of the (meth)acrylic polyol used in Example 1 is calculated as the hydroxyl equivalent of the (meth)acrylic polyol used in Example 1 (1802 g/equivanlent). ) to calculate the number of moles of hydroxyl group (0.0124 mol). By dividing the calculated number of moles of silane functional group (0.0252 mol) by the number of moles of hydroxy group (0.0124 mol), it is confirmed that the SiH/OH molar ratio is calculated as 2.

The lower limit of the SiH/OH molar ratio may be, for example, 1.6 or more, 1.7 or more, 1.8 or more, 1.9 or more, or 2.0 or more, and the upper limit may be, for example, 3.9 or less, 3.8 or less, 3.7 or less, 3.6 or less, or 3.5 or less. You can. When the above SiH/OH molar ratio range is satisfied, the polymer matrix is crosslinked at an appropriate crosslinking density to improve the fluidity of recording components (e.g., photoreactive monomers and plasticizers, etc.) to ensure excellent optical recording characteristics, Even if placed in a high temperature and/or high humidity environment before and after recording, the components in the photopolymer layer can be prevented from moving or deforming or moisture from penetrating into the photopolymer layer, thereby showing excellent heat resistance or moisture heat resistance.

A Pt-based catalyst may be used to crosslink the silane-based polymer and the (meth)acrylic-based polyol. The Pt-based catalyst used is not particularly limited, but may be, for example, Karstedt's catalyst.

The Pt-based catalyst may be included in an amount of 0.01 to 2 parts by weight based on 100 parts by weight of the (meth)acrylic polyol. Specifically, the Pt-based catalyst is, for example, 0.02 part by weight, 0.03 part by weight, 0.04 part by weight, 0.05 part by weight, or 0.06 part by weight, based on 100 parts by weight of the (meth)acrylic polyol, It may be included in 1.5 parts by weight or less, 1.0 parts by weight or less, 0.5 parts by weight or less, 0.3 parts by weight or less, 0.2 parts by weight or less, 0.15 parts by weight or less, 0.14 parts by weight or less, 0.13 parts by weight or less, or 0.12 parts by weight or less. When the Pt-based catalyst is used in the above-mentioned amount, the polymer matrix can be crosslinked at an appropriate crosslinking density to exhibit desired optical recording characteristics.

The polymer matrix precursor may, if necessary, be a Rhodium-based, Iridium-based, Rhenium-based, Molybdenum-based, Iron-based, Nickel-based, alkali metal or alkaline earth metal-based, Lewis acids-based or Carbene-based non-metallic catalyst in addition to the Pt-based catalyst. etc. may be additionally included.

Meanwhile, according to a specific example related to the present application, when manufacturing a hologram recording medium, optical information can be recorded by irradiating object light and reference light to the photopolymer (layer). Due to the interference field between the object light and the reference light, photopolymerization of the photoreactive monomer does not occur in the destructive interference area, but photopolymerization of the photoreactive monomer occurs in the constructive interference area. As the photoreactive monomer is continuously consumed in the constructive interference area, a concentration difference occurs between the photoreactive monomers in the destructive interference area and the constructive interference area, and as a result, the photoreactive monomer in the destructive interference area diffuses into the constructive interference area. A diffraction grating is created by the refractive index modulation that occurs in this way.

Accordingly, the photoreactive monomer may include a compound having a higher refractive index than the polymer matrix in order to implement the above-described refractive index modulation. However, all photoreactive monomers are not limited to having a higher refractive index than the polymer matrix, and at least some of the photoreactive monomers may have a higher refractive index than the polymer matrix so that a high refractive index modulation value can be realized. As an example, the photoreactive monomer may include a monomer with a refractive index of 1.50 or more, 1.51 or more, 1.52 or more, 1.53 or more, 1.54 or more, 1.55 or more, 1.56 or more, 1.57 or more, 1.58 or more, 1.59 or more, or 1.60 or more and 1.70 or less. there is.

In one example, the photoreactive monomer may include one or more monomers selected from the group consisting of a monofunctional monomer having one photoreactive functional group and a polyfunctional monomer having two or more photoreactive functional groups. At this time, the photoreactive functional group may be, for example, a (meth)acryloyl group, a vinyl group, or a thiol group. More specifically, the photoreactive functional group may be a (meth)acryloyl group.

The monofunctional monomers include, for example, benzyl (meth)acrylate (Miwon's M1182 refractive index 1.5140), benzyl 2-phenylacrylate, phenoxybenzyl (meth)acrylate (Miwon's M1122 refractive index 1.565), and phenol. (ethylene oxide) (meth)acrylate (phenol (EO) (meth)acrylate; Miwon's M140 refractive index 1.516), phenol (ethylene oxide) ₂ (meth)acrylate (phenol (EO) ₂ (meth)acrylate; Miwon Miwon's M142 refractive index 1.510), O -phenylphenol (ethylene oxide) (meth)acrylate ( O -phenylphenol (EO) (meth)acrylate; Miwon's M1142 refractive index 1.577), phenylthioethyl (meth)acrylate (Miwon It may include at least one member selected from the group consisting of the company's M1162 refractive index 1.560) and biphenylmethyl (meth)acrylate.

The multifunctional monomer is, for example, bisphenol A (ethylene oxide) _2-10 di(meth)acrylate (bisphenol A (EO) _2-10 (meth)acrylate; Miwon's M240 refractive index 1.537, M241 refractive index 1.529, M244 refractive index 1.545, M245 refractive index 1.537, M249 refractive index 1.542, M2100 refractive index 1.516, M2101 refractive index 1.512), Bisphenol A epoxy di(meth)acrylate (Miwon's PE210 refractive index 1.557, PE2120A refractive index 1.5 33, PE2120B refractive index 1.534, PE2020C refractive index 1.539, PE2120S refractive index 1.556), bisfluorene di(meth)acrylate (Miwon's HR6022 refractive index 1.600, HR6040 refractive index 1.600, HR6042 refractive index 1.600), modified bisphenol fluorene di(meth)acrylate (Miwon's HR 6060 refractive index 1.584) , HR6100 refractive index 1.562, HR6200 refractive index 1.530), tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate (Miwon's M370 refractive index 1.508), phenol novolak epoxy (meth)acrylate (Miwon's) It may include one or more selected from the group consisting of (SC6300 refractive index 1.525) and cresol novolak epoxy (meth)acrylate (Miwon's SC6400 refractive index 1.522, SC6400C refractive index 1.522).

The photopolymer (or photopolymer layer) composition may include 50 to 300 parts by weight of a photoreactive monomer based on 100 parts by weight of the polymer matrix. For example, the lower limit of the content of the photoreactive monomer may be 50 parts by weight or more, 70 parts by weight or more, 100 parts by weight or more, or 120 parts by weight or more, and the upper limit is 300 parts by weight or less, 270 parts by weight or less, and 250 parts by weight or less. It may be less than or equal to 220 parts by weight. At this time, the content of the polymer matrix, which is the standard, means the content (weight) of the (meth)acrylic polyol and siloxane-based polymer forming the matrix. When the above range is satisfied, excellent optical recording characteristics can be exhibited.

In one example, the photopolymer (or photopolymer layer) composition may further include a plasticizer. When a plasticizer is added to the photopolymer, refractive index modulation can be more easily implemented when recording a hologram. More specifically, the plasticizer improves the fluidity of the photoreactive monomer by lowering the glass transition temperature of the polymer matrix, and has a low refractive index and non-reactive properties, so it is uniformly distributed within the polymer matrix and then moves when the unphotoreactive monomer moves. It can contribute to refractive index modulation by moving in the opposite direction. Additionally, plasticizers can contribute to improving the moldability of photopolymer compositions.

Fluorine-based compounds may be used as such plasticizers.

The fluorine-based compound may have a low refractive index of 1.45 or less in order to perform the above-described plasticizer function. Specifically, the upper limit of the refractive index may be, for example, 1.44 or less, 1.43 or less, 1.42 or less, 1.41 or less, 1.40 or less, 1.40 or less, 1.39 or less, 1.38 or less, or 1.37 or less, and the lower limit of the refractive index may be, for example, 1.30 or less. It may be 1.31 or more, 1.32 or more, 1.33 or more, 1.34 or more, or 1.35 or more. Since a fluorine-based compound having a lower refractive index than the photoreactive monomer described above is used, the refractive index of the polymer matrix can be lowered, and the refractive index modulation with the photoreactive monomer can be increased.

The fluorine-based compound may include, for example, one or more functional groups selected from the group consisting of an ether group, an ester group, and an amide group, and two or more difluoromethylene groups. More specifically, the fluorine-based compound may be, for example, a compound containing a repeating unit represented by the following formula (5).

[Formula 5]

In Formula 5 above,

A plurality of R ³¹ to R ³⁴ are each independently hydrogen or fluorine, at least one of R ³¹ to R ³⁴ is fluorine, and m is an integer of 2 to 12.

More specifically, the fluorine-based compound may be a compound containing 1 to 3 units represented by the following Chemical Formula 5-1.

[Formula 5-1]

In Formula 5-1,

R ⁴¹ to R ⁴⁴ and R ⁵³ to R ⁵⁶ are each independently hydrogen or fluorine, and R ⁴⁵ to R ⁵² are fluorine.

For example, in Formula 5-1, R ⁴¹ , R ⁴² , R ⁵⁵ and R ⁵⁶ are hydrogen, and R ⁴³ to R ⁵⁴ are fluorine.

Fluorine-based compounds containing (repeating) units represented by Formulas 5 and 5-1 are not particularly limited, but may be capped with an end capping agent widely used in the related technical field. As an example, the terminal of the fluorine-based compound containing the (repeating) unit represented by Formulas 5 and 5-1 may be an alkyl group or an alkyl group substituted with one or more alkoxy. As a non-limiting example, using 2-methoxyethoxymethyl chloride as an end capping agent, the terminal of the fluorine-based compound containing (repeating) units represented by Formulas 5 and 5-1 is a 2-methoxyethoxymethyl group. You can.

The fluorine-based compound may have a weight average molecular weight of 300 or more. Specifically, the lower limit of the weight average molecular weight of the fluorine-based compound may be, for example, 350 or more, 400 or more, 450 or more, 500 or more, or 550 or more, and the upper limit may be, for example, 1000 or less, 900 or less, 800 or less, and 700 or less. Or it may be 600 or less. Considering refractive index modulation, compatibility with other components, and dissolution problems of fluorine-based compounds, it is preferable to satisfy the above weight average molecular weight range. At this time, the weight average molecular weight means the weight average molecular weight in terms of polystyrene measured by the GPC method as described above.

The photopolymer (or photopolymer layer) composition may include 20 to 200 parts by weight of the fluorine-based compound based on 100 parts by weight of the polymer matrix. Specifically, the lower limit of the content of the fluorine-based compound may be, for example, 25 parts by weight or more, 30 parts by weight or more, 40 parts by weight or more, 50 parts by weight or more, 60 parts by weight or more, 70 parts by weight or more, or 80 parts by weight or more. , the upper limit may be, for example, 190 parts by weight or less, 180 parts by weight or less, 170 parts by weight or less, 160 parts by weight or less, or 150 parts by weight or less. When the above range is satisfied, the fluorine-based compound has a sufficiently low refractive index without problems such as poor compatibility with the components included in the photopolymer layer, causing some fluorine-based compounds to elute to the surface of the photopolymer layer or worsen haze after recording. It can exhibit a large refractive index modulation value, which is advantageous in securing excellent optical recording characteristics.

The photopolymer (or photopolymer layer) composition includes a photoinitiator system. The photoinitiator system may refer to a combination of a photoinitiator or a photosensitizer and a coinitiator that allows polymerization to be initiated by light. For example, the photopolymer (or photopolymer layer) composition may include a photosensitizer and a coinitiator as a photoinitiator system.

The photoinitiator system included in the composition is a component that allows polymerization to be initiated by light, and may further include other components in addition to the compound containing the anion of Formula 1 and the cation of Formula 2 described above. For example, the photoinitiator system may include a photosensitizer and an initiator. At this time, the compound containing the anion of Formula 1 and the cation of Formula 2 described above can be viewed as a (co)initiator or a component thereof.

As the photosensitizer, for example, a photosensitivity dye may be used. The photosensitive dye serves as a sensitizing dye that increases or decreases the photoinitiator. Specifically, the photosensitive dye can also serve as an initiator to initiate polymerization of photoreactive monomers by being stimulated by light irradiated to the composition.

Specifically, the photosensitive dyes include, for example, silicon rhodamine compounds, sulfonium derivatives of ceramidonin, new methylene blue, thioerythrosine triethylammonium, 6-acetylamino-2-methylceramidonin, eosin, erythrosine, rose bengal, thionine, basic yellow ), Pinacyanol chloride, rhodamine 6G, gallocyanine, ethyl violet, Victoria blue R, Celestine blue, Quinaldine Red, crystal violet, brilliant green, Astrazon orange G, darrow red, pyronin Y, basic red 29 (basic red 29), pyrylium iodide, Safranin O, cyanine, methylene blue, Azure A and BODIPY. You can use it.

As an example, a silicon rhodamine compound represented by the following formula (6) may be used as the photosensitive dye.

[Formula 6]

In Formula 6 above,

R ²¹ to R ²⁹ are each independently hydrogen, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, or It is a substituted or unsubstituted aryloxy group having 6 to 30 carbon atoms,

d and e are each independently integers from 0 to 3,

f is an integer from 0 to 5,

An ^- is an anion.

In relation to Formula 6, “substituted or unsubstituted” means that hydrogen or carbon is replaced with another element, and hydrogen may be substituted with a halogen, a hydroxy group, an alkyl group with 1 to 10 carbon atoms, or an alkoxy group with 1 to 10 carbon atoms, , carbon (-CH ₂ -) may be substituted with -O- or -CO-.

In one example, R ²¹ to R ²⁸ in Formula 6 may each independently be a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms. Specifically, in Formula 6, R ²¹ to R ²⁸ may each independently be an alkyl group having 1 to 6 carbon atoms. More specifically, in Formula 6, R ²¹ to R ²⁸ may be a methyl group.

In one example, d and e in Formula 6 may each independently be an integer of 0 to 2, an integer of 0 to 1, or 0.

In one example, f in Formula 6 may be an integer of 0 to 5, an integer of 0 to 4, an integer of 0 to 3, an integer of 0 to 2, or an integer of 1 to 2.

In one example, R ²⁹ in Formula 6 may be a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms. Specifically, in Formula 6, R ²⁹ may be an alkoxy group having 1 to 6 carbon atoms. More specifically, in Formula 6, R ²⁹ may be a methoxy group.

In one example, the anion (An ^- ) of Formula 6 is a halide anion, a cyano anion, a sulfonate anion, an alkoxy anion having 1 to 30 carbon atoms, a substituted or unsubstituted alkyl sulfonate anion having 1 to 30 carbon atoms, or a substituted anion. Alternatively, it may be an unsubstituted aromatic sulfonate anion having 6 to 30 carbon atoms, or a substituted or unsubstituted aromatic borate anion having 6 to 30 carbon atoms.

Specifically, the anion (An ^- ) of Formula 6 is a substituted or unsubstituted alkyl sulfonate anion having 1 to 30 carbon atoms, a substituted or unsubstituted aromatic sulfonate anion having 6 to 30 carbon atoms, or a substituted or unsubstituted carbon number. It may be 6 to 30 aromatic borate anions.

또는 테트라페닐보레이트 음이온일 수 있다.More specifically, in Formula 6, the anion (An ^- ) is an alkyl sulfonate anion having 2 to 15 carbon atoms in which at least one hydrogen is substituted or unsubstituted with fluorine, and at least one carbon is substituted or unsubstituted with -O- or -CO-. It may be a ringed alkyl sulfonate anion having 6 to 30 carbon atoms, a methyl-substituted or unsubstituted phenyl sulfonate anion, or a substituted or unsubstituted tetraaryl borate anion. For example, in Formula 6, the anion (An ^- ) is a dodecyl sulfonate anion, a perfluorobutyl sulfonate anion, a phenyl sulfonate anion, a methylphenyl sulfonate anion,

Or it may be a tetraphenylborate anion.

When using the above-described silicon rhodamine compound as a photosensitive dye, the combination of the above-described electron donor and the photosensitive dye exhibits a reaction energy in the above-mentioned range, ensuring excellent stability over time and at the same time showing excellent sensitivity, which can be used in all aspects of holographic recording media. It can exhibit excellent properties such as diffraction efficiency, refractive index modulation value, image reproducibility, and angle selectivity.

The photopolymer (or photopolymer layer) composition may include the photosensitive dye in the range of 0.01 to 10 parts by weight based on 100 parts by weight of the polymer matrix. Specifically, the lower limit of the content of the photosensitive dye may be, for example, 0.02 parts by weight or more, 0.03 parts by weight or more, or 0.05 parts by weight or more, and the upper limit may be, for example, 5 parts by weight or less. When the above range is satisfied, it is advantageous to secure the desired optical recording characteristics by showing an appropriate polymerization reaction rate.

In one example, the (co)initiator may be an electron donor, an electron acceptor, or a mixture thereof. At this time, a compound containing the anion of Formula 1 and the cation of Formula 2 described above may be used as the electron donor. This electron donor can produce a specific reaction energy with the above-described photosensitive dye. Through this, the hologram recording medium can have excellent stability over time.

Specifically, the electron donor participates in the photopolymerization initiation reaction by reacting with the photosensitive dye excited to a triplet state by light irradiation as shown in Scheme 1 below.

[Scheme 1]

At this time, if an electron donor with a reaction energy of -25 to 0 kJ/mol with a photosensitive dye excited in a triplet state is used, the reaction does not start even at room temperature or high temperature before light irradiation, showing excellent stability over time and when light is irradiated. A sensitive photo-initiated reaction occurs, resulting in excellent optical recording properties.

More specifically, the electron donor has a reaction energy with a photosensitive dye excited in a triplet state of - 25 kJ/mol or more, - 20 kJ/mol or more, - 15 kJ/mol or more, - 14 kJ/mol or more, - 13 kJ/mol or more, - 12 kJ/mol or more, - 11 kJ/mol or more, - 10 kJ/mol or more, - 9 kJ/mol or more, or - 8.5 kJ/mol or more and 0 kJ/mol or less, - 3 kJ It may satisfy /mol or less or -5 kJ/mol or less. For the method of measuring the reaction energy, refer to the measurement method described in detail in the test example described later.

In one example, the initiator may further include an electron acceptor. When an electron acceptor is received and an electron acceptor is included during a redox reaction of a photoinitiator system, the total energy E2 of the photoinitiator system reaction increases toward a negative value. However, as a result of the present inventors' research, even if the total energy of the photoinitiator system reaction changes due to the inclusion of the electron acceptor, excellent stability over time can be secured only when the reaction energy of the photosensitive dye and the electron donor is within the above-mentioned range.

Such electron acceptors include, for example, onium salts such as sulfonium salts, iodonium salts, etc.; triazine compounds such as tris(trihalomethyl)triazine, substituted bis(trihalomethyl)triazine, etc.; Or it may include a mixture thereof.

Specifically, the electron acceptor includes (4-(octyloxy)phenyl)(phenyl)iodonium salt as an iodonium salt, or 2-(4-methoxyphenyl)-4,6-bis as a triazine compound. It may include (trichloromethyl)-1,3,5-triazine. Examples of the electron acceptor include commercially available H-Nu 254 (Spectra) or 2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-1,3, 5-Triazine (TCI) can be used.

Among these, a triazine compound can be used as the electron acceptor. When a triazine compound is used as an electron acceptor, the stability over time at high temperatures of the hologram recording medium before recording can be further improved.

The photopolymer (or photopolymer layer) composition may include the co-initiator in the range of 0.05 to 10 parts by weight based on 100 parts by weight of the polymer matrix. Specifically, the lower limit of the content of the disclosure agent may be, for example, 0.1 part by weight or more, 0.5 part by weight or more, 1 part by weight or more, 1.5 part by weight or more, or 2 parts by weight or more, and the upper limit is, for example, 5 parts by weight. It may be less than 100%. When the above range is satisfied, it is advantageous to secure the desired optical recording characteristics by showing an appropriate polymerization reaction rate.

The photoinitiator system may include an additional photoinitiator to remove the color of the photosensitive dye and react all unreacted photoreactive monomers after irradiation with light for recording. Such photoinitiators include, for example, imidazole derivatives, bisimidazole derivatives, N-aryl glycine derivatives, organic azide compounds, titanocene, aluminate complexes, organic peroxides, N-alkoxy pyridinium salts, thioxanthone derivatives. , amine derivatives, diazonium salt, sulfonium salt, iodonium salt, sulfonic acid ester, imide sulfonate, dialkyl-4-hydroxy sulfonium salt, aryl sulfonic acid- p-nitro benzyl ester, silanol-aluminum complex, (η6-benzene) (η5-cyclopentadienyl)iron(II), benzoin tosylate, 2,5-dinitro benzyl tosylate, N-tosylphthalate or mixtures thereof may be used. More specifically, the photoinitiator includes 1,3-di(t-butyldioxycarbonyl)benzophenone, 3,3',4,4''-tetrakis(t-butyldioxycarbonyl)benzophenone, 3-phenyl-5-isoxazolone, 2-mercapto benzimidazole, bis(2,4,5-triphenyl)imidazole, 2,2-dimethoxy-1,2-diphenylethane-1-one (Product name: Irgacure 651 / Manufacturer: BASF), 1-hydroxy-cyclohexyl-phenyl-ketone ( Product name: Irgacure 184 / Manufacturer: BASF), 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1 (Product name: Irgacure 369 / Manufacturer: BASF), bis(η5-2,4-cyclopentadiene- 1-yl)-bis(2,6-difluoro-3-(1H-pyrrole-1-yl)-phenyl)titanium (Product name: Irgacure 784 / Manufacturer: BASF), Ebecryl P-115 (Manufacturer: SK entis), Cyracure UVI-6970, Cyracure UVI-6974, Cyracure UVI-6990 (manufacturer: Dow Chemical Co. in USA), Irgacure 264, Irgacure 250 (manufacturer: BASF), CIT-1682 (manufacturer: Nippon Soda) or mixtures thereof, etc. Examples include, but are not limited to these.

The photopolymer (or photopolymer layer) composition may include the photoinitiator in the range of 0.05 to 10 parts by weight based on 100 parts by weight of the polymer matrix. Specifically, the lower limit of the content of the photoinitiator may be, for example, 0.1 parts by weight or more, 0.5 parts by weight or more, 1 part by weight or more, 1.5 parts by weight or more, or 2 parts by weight or more, and the upper limit is, for example, 5 parts by weight. It may be below. When the above range is satisfied, a transparent hologram recording medium can be provided by recording optical information on the photopolymer layer, effectively terminating the reaction of the photoreactive monomer, and discoloring the photosensitive dye.

In addition, the composition may further include known additives (surfactants, antifoaming agents, etc.) or solvents.

Surfactants may include, for example, silicone-based surfactants, fluorine-based surfactants, or mixtures thereof.

The silicone-based surfactant includes, for example, BYK-077, BYK-085, BYK-300, BYK-301, BYK-302, BYK-306, BYK-307, BYK-310, BYK-320 manufactured by BYK Chemie, BYK-322, BYK-323, BYK-325, BYK-330, BYK-331, BYK-333, BYK-335, BYK-341v344, BYK-345v346, BYK-348, BYK-354, BYK355, BYK-356, BYK-358, BYK-361, BYK-370, BYK-371, BYK-375, BYK-380, BYK-390, BYK-3550, etc. are available. In addition, the fluorine-based surfactants include F-114, F-177, F-410, F-411, F-450, F-493, F-494, F-443, and F- manufactured by DIC (DaiNippon Ink & Chemicals). 444, F-445, F-446, F-470, F-471, F-472SF, F-474, F-475, F-477, F-478, F-479, F-480SF, F-482, F-483, F-484, F-486, F-487, F-172D, MCF-350SF, TF-1025SF, TF-1117SF, TF-1026SF, TF-1128, TF-1127, TF1129, TF-1126, TF-1130, TF-1116SF, TF-1131, TF1132, TF1027SF, TF-1441, TF-1442, etc. are available. However, it is not limited to those listed above.

If the photopolymer (or photopolymer layer) composition includes a surfactant, the surfactant may be used in an amount of 0.01 part by weight, 0.02 part by weight, 0.03 part by weight, or 0.05 part by weight, based on 100 parts by weight of the polymer matrix. It may contain less than or equal to 3 parts by weight. When the above range is satisfied, excellent optical recording properties can be preserved by providing excellent adhesiveness and release properties to the photopolymer layer.

As an antifoaming agent, for example, a silicone-based reactive additive may be used. As the silicone-based reactive additive, for example, commercial products such as Tego Rad 2500 can be used. The content of the antifoaming agent can be appropriately adjusted to a level that does not interfere with the function of the hologram recording medium.

In one example, the composition may include a solvent.

The solvent included in the composition may be an organic solvent, for example, one or more organic solvents selected from the group consisting of ketones, alcohols, acetates, and ethers, but is not limited thereto. Specific examples of such organic solvents include ketones such as methyl ethyl ketone, methyl isobutyl ketone, acetylacetone, and isobutyl ketone; Alcohols such as methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, or t-butanol; Acetates such as ethyl acetate, i-propyl acetate, or polyethylene glycol monomethyl ether acetate; and one or more selected from the group consisting of ethers such as tetrahydrofuran or propylene glycol monomethyl ether.

This solvent may be added when each component included in the composition is mixed, or may be included in the composition while each component is added in a dispersed or mixed state in an organic solvent.

The photopolymer composition may include a solvent so that the solid content concentration is 1 to 90% by weight. Specifically, the photopolymer composition may contain a solvent so that the solid concentration is 20% by weight or more, 25% by weight or more, or 30% by weight or less, and 50% by weight or less, 45% by weight or less, or 40% by weight or less. . Within this range, the photopolymer composition exhibits appropriate flowability and can form a coating film without defects such as streaks, and no defects occur during the drying and curing process, thereby forming a photopolymer that exhibits desired physical and surface properties. .

In another example related to this application, this application relates to holographic recording media.

In this specification, “hologram recording medium” refers to a medium (medium) capable of recording optical information in the entire visible light range and ultraviolet range (e.g., 300 to 1,200 nm) through an exposure process, unless specifically stated otherwise. or media). Accordingly, the hologram recording medium of this specification may refer to a medium on which optical information is recorded, or may refer to a pre-recording medium capable of recording optical information. Holograms herein include in-line (Gabor) holograms, off-axis holograms, full-aperture holograms, white light transmission holograms (“rainbow holograms”), and Denisyuk. ) All visual holograms such as holograms, biaxial reflection holograms, edge-literature holograms, or holographic stereograms may be included.

In one example, the hologram recording medium includes a polymer matrix formed by crosslinking a siloxane-based polymer containing a silane functional group and a (meth)acrylic-based polyol; and a photopolymer layer containing a photoreactive monomer and a photoinitiator system or a photopolymer obtained therefrom. In addition, the hologram recording medium or photopolymer layer satisfies that the lowest transmittance change calculated by Equation 1 below is 20% or less.

[Equation 1]

△T(%) = {(│T _{1 -} T ₀ │)/ T ₀ }

In Equation 1, T ₀ is 300 to 300 using a UV-Vis spectrometer for the sample on which the notch filter hologram was recorded after storing the hologram recording medium before recording in a dark room at a temperature of 20 to 25 ℃ and relative humidity of 40 to 50%. The lowest transmittance measured in the wavelength range of 1,200 nm,

T ₁ is the lowest transmittance measured as above for the sample on which the notch filter hologram was recorded after the hologram recording medium was stored for 100 hours in a dark room at a temperature of 60 ° C. and a relative humidity of 40 to 50% before recording.

The photopolymer layer may be a photopolymer layer in a pre-recording state capable of recording optical information, or may be a photopolymer layer in a state in which optical information is recorded.

A photopolymer layer with optical information recorded can be manufactured by irradiating object light and reference light to the photopolymer layer before recording. When object light and reference light are irradiated to the photopolymer layer before recording, the photoinitiator system is in an inactive state in the destructive interference area due to the interference field of the object light and reference light, so photopolymerization of the photoreactive monomer does not occur, and the activated photoinitiator system does not occur in the constructive interference area. This causes photopolymerization of the photoreactive monomer. As the photoreactive monomer is continuously consumed in the constructive interference area, a concentration difference occurs between the photoreactive monomer in the destructive interference area and the constructive interference area. As a result, the photoreactive monomer in the destructive interference region diffuses into the constructive interference region. Since the photoreactive monomer and the photopolymer formed therefrom have a high refractive index compared to the polymer matrix, spatial changes in refractive index occur in the photopolymer layer, and a grid is created due to the spatial refractive index modulation occurring in the photopolymer layer. This grating surface serves as a reflective surface that reflects incident light due to the difference in refractive index, and when light of the same wavelength is incident when recording in the direction of the reference light after recording the hologram, the Bragg condition is satisfied and the light diffracts in the direction of the original object light. Holographic optical information can be reproduced.

Therefore, if the photopolymer layer is in a state before recording, the photopolymer layer may include photoreactive monomers and a photoinitiator system in a randomly dispersed form within the polymer matrix.

On the other hand, if optical information is recorded in the photopolymer layer, the photopolymer layer may include a photopolymer distributed to form a polymer matrix and a lattice.

The change in minimum transmittance calculated by Equation 1 is an indicator for evaluating the temporal stability of the holographic recording medium before recording, especially at high temperature (60° C.). The holographic recording medium of the embodiment is left at high temperature for 100 hours before recording. Even so, the optical recording characteristics can be displayed at the originally intended level.

Specifically, the hologram recording medium of the embodiment has a change in minimum transmittance (△T) calculated by Equation 1 of 20% or less, 19% or less, 18% or less, 17% or less, 16% or less, 15% or less, 14% or less, 13% or less, 12% or less, 11% or less, 10% or less, 9% or less, 8% or less, 7% or less, 6% or less, 5% or less, 4% or less, 3% or less, 2% or less It may be less than or less than 1%. The lower limit of the change in minimum transmittance (ΔT) calculated using Equation 1 is not particularly limited and may be 0% or more.

The photopolymer layer includes a polymer matrix formed by crosslinking a siloxane-based polymer containing a silane functional group and a (meth)acrylic-based polyol; Photoreactive monomer; and a photoinitiator system.

The photopolymer layer may have the same composition as the composition described above, and in this case, the description of the polymer matrix, photoreactive monomer, and high-initiator system is the same as that described above, and thus is omitted.

When the photopolymer layer contains a fluorine-based compound and the elemental composition measured on the surface of the photopolymer layer satisfies a certain ratio, it can exhibit excellent optical recording characteristics and excellent stability over time even at high temperatures.

Specifically, using photoelectron spectroscopy, called X-ray Photoelectron Spectroscopy (XPS) or Electron Spectroscopy for Chemical Analysis (ESCA), the element ratio on the surface of the photopolymer layer can be confirmed. According to the photoelectron spectroscopy method described in the test example described later, the elements found on the surface of the sample to be analyzed can be qualitatively analyzed through a survey scan, and then the element ratio can be measured by performing a narrow scan for each element found. As described in the test examples described later, the element ratio of the photopolymer layer before recording and the element ratio of the photopolymer layer after recording may be the same.

The carbon element ratio on the surface of the photopolymer layer included in the hologram recording medium of one embodiment is 50 atomic% or more, 51 atomic% or more, 52 atomic% or more, 53 atomic% or more, or 54 atomic% or more, and 70 atomic% or less, It may be 69 atomic% or less or 68 atomic% or less.

The nitrogen element ratio on the surface of the photopolymer layer is 0.01 atomic % or more, 0.05 atomic % or more, 0.10 atomic % or more, or 0.20 atomic % or more, and 2 atomic % or less, 1.8 atomic % or less, 1.6 atomic % or less, 1.4 atomic % or less. Or it may be 1.2 atomic% or less.

The oxygen element ratio on the surface of the photopolymer layer is 15 atomic% or more, 16 atomic% or more, or 17 atomic% or more, and 30 atomic% or less, 29 atomic% or less, 28 atomic% or less, 27 atomic% or less, or 26 atomic% or less. You can.

The fluorine element ratio on the surface of the photopolymer layer may be 3 atomic% or more, or 4 atomic% or more, and 12 atomic% or less, 11 atomic% or less, or 10 atomic% or less.

The silicon element ratio on the surface of the photopolymer layer may be 3 atomic% or more, 4 atomic% or more, 4.5 atomic% or more, and 15 atomic% or less.

The carbon, nitrogen, oxygen, fluorine and silicon element ratios are percentages (atomic percent) relative to the total amount of carbon, nitrogen, oxygen, fluorine and silicon atoms confirmed by photoelectron spectroscopy on the surface of the photopolymer layer.

As the photopolymer layer exhibits the above-described elemental composition ratio, it can exhibit excellent optical recording properties and excellent stability over time at high temperatures. In particular, if the fluorine element ratio is less than the above range, the optical recording characteristics may deteriorate, and if the fluorine element ratio exceeds the above range, there may be a problem of deterioration of stability over time due to vulnerability to moisture. In addition, if the silicon element ratio is less than the above range, there may be a problem of vulnerability to heat and increased haze, and if the silicon element ratio exceeds the above range, there may be a problem that optical recording characteristics are greatly reduced.

Most of the components of the photopolymer layer can be said to be a polymer matrix, a photoreactive monomer, and a fluorine-based compound that is a plasticizer added as needed. Therefore, the elemental composition of the surface of the photopolymer layer can be controlled through the mixing ratio of the polymer matrix, photoreactive monomer, and fluorine-based compound. In order to satisfy the above-described elemental composition, the photopolymer layer contains 17 to 38% by weight of the polymer matrix, 33 to 58% by weight of the photoreactive monomer, and a fluorine-based compound, based on the total weight of the polymer matrix, photoreactive monomer, and fluorine-based compound. It may contain 17 to 38 weight%.

More specifically, the polymer matrix may include, for example, 17 wt% or more, 18 wt% or more, 19 wt% or more, or 20 wt% or more and 38 wt% or less, 37 wt% or less, or 36 wt% or less. there is. For example, the photoreactive monomer may be included in 33 wt% or more, 35 wt% or more, or 38 wt% or more and 58 wt% or less, 55 wt% or less, or 53 wt% or less. For example, the fluorine-based compound may be included in an amount of 17 wt% or more, 18 wt% or more, 19 wt% or more, or 20 wt% or more and 38 wt% or less, 35 wt% or less, 33 wt% or less, or 32 wt% or less. You can. Within this range, it is possible to provide a photopolymer layer that satisfies the above-described elemental composition ratio.

The hologram recording medium of the above embodiment has excellent refractive index modulation, diffraction efficiency, and driving reliability despite having a thin photopolymer layer.

The thickness of the photopolymer layer may range from 5.0 to 40.0 μm, for example. Specifically, the lower limit of the photopolymer layer thickness may be, for example, 6 μm or more, 7 μm or more, 8 μm or more, or 9 μm or more. And, the upper limit of the thickness is, for example, 35 ㎛ or less, 30 ㎛ or less, 29 ㎛ or less, 28 ㎛ or less, 27 ㎛ or less, 26 ㎛ or less, 25 ㎛ or less, 24 ㎛ or less, 23 ㎛ or less, 22 ㎛ or less. Hereinafter, it may be 21 ㎛ or less, 20 ㎛ or less, 19 ㎛ or less, or 18 ㎛ or less.

The hologram recording medium of the embodiment may further include a substrate on at least one side of the photopolymer layer. The type of base material is not particularly limited, and those known in the related technical field can be used. For example, substrates such as glass, polyethylene terephthalate (PET), triacetyl cellulose (TAC), polycarbonate (PC), and cycloolefin polymer (COP) may be used.

The hologram recording medium of the above embodiment may have high diffraction efficiency. As an example, the hologram recording medium may have a diffraction efficiency of 80% or more when recording a notch filter hologram. At this time, the thickness of the photopolymer layer may be, for example, 5 to 30 ㎛. Specifically, the diffraction efficiency when recording the notch filter hologram may be 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, or 92% or more. As such, the hologram recording medium of the embodiment can achieve excellent diffraction efficiency even if it includes a thin photopolymer layer. The diffraction efficiency can be measured by the method described in the test example described later.

The hologram recording medium of the embodiment is not limited thereto, but may be one on which a reflective hologram or a transmissive hologram is recorded.

Meanwhile, according to another embodiment of the invention, a polymer matrix or a precursor thereof formed by crosslinking a siloxane-based polymer containing a silane functional group and a (meth)acrylic-based polyol; Photoreactive monomer; and applying and drying a photopolymer composition containing a photoinitiator system to form a photopolymer layer, thereby manufacturing a hologram recording medium before recording with a change in minimum transmittance of 20% or less as calculated by Equation 1 below; and recording optical information by selectively polymerizing photoreactive monomers included in the photopolymer layer by irradiating a coherent laser to a predetermined area of the photopolymer layer.

[Equation 1]

△T(%) = {(│T1 - T0│)/ T0}

In Equation 1, T0 is 300 to 1,200 using a UV-Vis spectrometer for the sample on which the notch filter hologram was recorded after storing the hologram recording medium before recording in a dark room at a temperature of 20 to 25 ℃ and relative humidity of 40 to 50%. is the lowest transmittance measured in the wavelength range of nm,

T1 is the lowest transmittance measured as above for the sample on which the notch filter hologram was recorded after the hologram recording medium was stored for 100 hours in a dark room at a temperature of 60 ° C. and a relative humidity of 40 to 50% before recording.

Since the hologram recording medium and the photopolymer layer included therein, which have a change in minimum transmittance calculated by Equation 1 above of 20% or less, have been described in detail previously, detailed descriptions will be omitted here.

In the step of forming the photopolymer layer, a photopolymer composition containing the above-described structure can first be prepared. When manufacturing the photopolymer composition, a commonly known mixer, stirrer, or mixer can be used to mix each component without any restrictions. And, this mixing process may be performed at a temperature ranging from 0°C to 100°C, a temperature ranging from 10°C to 80°C, or a temperature ranging from 20°C to 60°C.

In the step of forming the photopolymer layer, the prepared photopolymer composition may be applied to form a coating film formed from the photopolymer composition. The coating film may be dried at a temperature of 50 ℃ or higher, 55 ℃ or higher, 60 ℃ or higher, 65 ℃ or higher or 70 ℃ or lower and 120 ℃ or lower, 110 ℃ or lower, 100 ℃ or lower or 90 ℃ or lower. Through this process, the desired crosslinking density can be achieved by inducing a hydrosilylation reaction between the hydroxy group of the (meth)acrylic polyol that remains unreacted and the silane functional group of the siloxane polymer.

In the photopolymer layer prepared through the step of forming the photopolymer layer, photoreactive monomers, a photoinitiator system, and additives added as necessary may be uniformly dispersed within the crosslinked polymer matrix.

Then, in the step of recording optical information, when the photopolymer layer is irradiated with a coherent laser, polymerization of the photoreactive monomer occurs in the area where constructive interference occurs to form a photopolymer, and in the area where destructive interference occurs, the photoreactive monomer is formed. Polymerization does not occur or is suppressed, resulting in the presence of a photoreactive monomer. In addition, the unreacted photoreactive monomer diffuses toward the photopolymer with a lower concentration of the photoreactive monomer, causing refractive index modulation, and a diffraction grating is created by the refractive index modulation. Accordingly, holograms, i.e. optical information, are recorded on the photopolymer layer with the diffraction grating.

The method of manufacturing a hologram recording medium according to another embodiment may further include the step of photobleaching the photopolymer layer on which the optical information is recorded by irradiating light as a whole after the step of recording the optical information.

In the photobleaching step, ultraviolet rays are irradiated to the photopolymer layer on which optical information is recorded to terminate the reaction of the photoreactive monomer remaining in the photopolymer layer, and the color of the photosensitive dye can be removed. For example, in the photobleaching step, ultraviolet rays (UVA) in the range of 320 to 400 nm are irradiated to terminate the reaction of the photoreactive monomer and remove the color of the photosensitive dye.

Meanwhile, according to another embodiment of the invention, an optical element including the hologram recording medium is provided.

Specific examples of the optical elements include smart devices such as mobile devices, wearable display components, vehicle products (e.g., head up display), holographic fingerprint recognition systems, optical lenses, mirrors, deflecting mirrors, filters, diffusion screens, and diffraction members. , holographic optical elements having the functions of light guides, waveguides, projection screens and/or masks, media and light diffusion plates of optical memory systems, optical wavelength splitters, reflective and transmissive color filters, etc.

An example of an optical element including the hologram recording medium may be a hologram display device. The holographic display device includes a light source unit, an input unit, an optical system, and a display unit.

Specifically, the light source unit is a part that emits a laser beam used to provide, record, and reproduce 3D image information of an object in the input unit and display unit.

The input unit is a part that pre-inputs the 3D image information of the object to be recorded on the display unit. Specifically, the 3D information of the object, such as the intensity and phase of light in each space, is input to an electrically driven liquid crystal SLM (electrically addressed liquid crystal SLM). Input is possible, and this is the part where the input beam can be used.

The optical system may be composed of a mirror, polarizer, beam splitter, beam shutter, lens, etc. The optical system can distribute the laser beam emitted from the light source unit into an input beam sent to the input unit, a recording beam sent to the display unit, a reference beam, an erase beam, a read beam, etc.

The display unit can receive 3D image information of an object from an input unit, record it on a hologram plate made of an optically driven SLM (optically addressed SLM), and reproduce the 3D image of the object. At this time, 3D image information of the object can be recorded through interference between the input beam and the reference beam. The 3D image information of the object recorded on the hologram plate can be reproduced as a 3D image by a diffraction pattern generated by the readout beam, and an erase beam can be used to quickly remove the formed diffraction pattern. Meanwhile, the hologram plate can be moved between a position where a 3D image is input and a position where it is played.

According to an embodiment of the present application, a hologram recording medium manufactured using the initiator compound of the present application, an initiator system and composition containing the same is provided. Since the holographic recording medium exhibits excellent stability over time before recording optical information, it can exhibit the originally intended optical recording characteristics even if stored for a long time at room temperature or high temperature. In addition, the holographic recording medium exhibits excellent physical properties such as diffraction efficiency, which are fundamentally required for a holographic recording medium.

Figure 1 schematically shows the recording equipment setup for hologram recording. Specifically, Figure 1 shows that a laser of a predetermined wavelength is irradiated from a light source 10, and then the laser is irradiated through a mirror (20, 20'), an iris (30), and a spatial filter ( 40), Iris (30'), collimation lens (50), and splitter (PBS, Polarized Beam Splitter) (60), PP (holographic recording medium) located on one side of the mirror (70) (80) schematically shows the process investigated.

Hereinafter, the operation and effects of the invention will be described in more detail through specific examples of the invention. However, this is presented as an example of the invention, and the scope of the invention is not limited by this in any way.

In the following production examples, examples, and comparative examples, the content of raw materials, etc. refers to the content based on solid content, unless otherwise specified.

Manufacturing example

Preparation Example 1: Preparation of (meth)acrylic polyol

132 g of butyl acrylate, 420 g of ethyl acrylate, and 48 g of hydroxybutyl acrylate were added to a 2 L jacketed reactor, and diluted with 1200 g of ethyl acetate. . The reaction temperature was set to 60-70°C, and stirring was performed for about 30 minutes to 1 hour. An additional 0.42 g of n-dodecyl mercaptan (n-DDM) was added, and stirring was continued for another 30 minutes. Afterwards, 0.24 g of AIBN, a polymerization initiator, was added, polymerization was carried out at the reaction temperature for more than 4 hours, and the residual acrylate content was maintained at less than 1%, resulting in a (meth)acrylate-based copolymer in which the hydroxyl group is located in the branched chain. (Weight average molecular weight approximately 300,000, OH equivalent weight approximately 1802 g/equivalent) was prepared.

Preparation Example 2: Preparation of fluorine-based compound

After adding 20.51 g of 2,2'-{oxybis[(1,1,2,2-tetrafluoroethane-2,1-diyl)oxy]}bis(2,2-difluoroethan-1-ol) to a 1000 mL flask. , was dissolved in 500 g of tetrahydrofuran and 4.40 g of sodium hydride (60% dispersion in mineral oil) was carefully added several times while stirring at 0°C. After stirring at 0°C for 20 minutes, 12.50 mL of 2-methoxyethoxymethyl chloride was slowly dropped. When it was confirmed that all the reactants were consumed by 1H NMR, 29 g of a liquid product with a purity of 95% or more was obtained with a yield of 98% through work-up using dichloromethane. The weight average molecular weight of the prepared fluorine-based compound was 586, and the refractive index measured with an Abbe refractometer was 1.361.

Examples and Comparative Examples: Preparation of holographic recording medium

Example 1

(1) Preparation of photopolymer composition

As a siloxane polymer, trimethylsilyl terminated poly(methylhydrosiloxane) (manufactured by Sigma-Aldrich, number average molecular weight: about 390, SiH equivalent about 103 g/equivalent) and (meth)acrylic polyol prepared in Preparation Example 1 were first mixed. The content of the (meth)acrylic polyol was 22.4 g, and the siloxane-based polymer was added so that the SiH/OH molar ratio was 2. In Example 1, 2.6 g of siloxane-based polymer was added.

In addition, 52 g of HR 6042 (Miwon, refractive index 1.60) as a photoreactive monomer, 0.2 g of a compound represented by the following formula (a) as a photosensitive dye, and 0.8 g of hexadecyl dimethyl benzyl ammonium tri(p-chlorophenyl)butyl borate as a co-initiator. g, 2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-1,3,5-triazine (TCI) 0.05 g, 0.9 g of Irgacure 369 as a photoinitiator, Preparation Example 2 as a plasticizer 23 g of the fluorine-based compound prepared in and 190 g of methyl isobutyl ketone (MIBK) as a solvent were added, and stirred for about 30 minutes with a paste mixer while blocking light. Afterwards, 0.014 g of Karstedt (Pt-based) catalyst was added for matrix crosslinking to prepare a photopolymer composition.

[Formula a]

(2) Manufacturing of holographic recording media

The photopolymer composition was coated to a predetermined thickness on a 60 ㎛ thick TAC substrate using a Meyer bar and dried at 80°C for 10 minutes. The thickness of the photopolymer layer after drying was about 15 μm.

Example 2 and Comparative Examples 1 to 3

A hologram recording medium was manufactured in the same manner as Example 1, except that the open tense was changed as shown in Table 1 below.

electron donor electron acceptor Example 1 Hexadecyl dimethyl benzyl ammonium tri(p-chlorophenyl)butyl borate 2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-1,3,5-triazine Example 2 Hexadecyl Benzyl Pyrrolidinium Tri(p-Chlorophenyl)Butyl Borate - Comparative Example 1 WPBG-300 (1,2-dicyclohexyl-4,4,5,5-tetramethylbiguanidium tri(phenyl)butyl borate) - Comparative Example 2 WPBG-300 2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-1,3,5-triazine Comparative Example 3 Tetrabutyl ammonium tri(o-methylphenyl)hexyl borate -

Test Example 1: Analysis of hologram recording medium

(1) Element ratio

The elemental ratios of the surfaces were analyzed for the pre-recording and post-recording samples by the method described below.

Specifically, the sample to be analyzed was fixed on a copper foil with carbon tape, placed on a sample holder and fixed using a clip. Then, data were acquired using an The element ratio (atomic %) of the sample surface was analyzed.

The system specifications of the ESCA device used are as follows.

- Base chamber pressure: ^1.0

- X-ray source: monochromatic Al Kα (1486.6 eV)

- X-ray spot size: 400 ㎛

- Mode: CAE (Constant Analyzer Energy) mode

- Charge compensation: Flood gun (FG03: 100 ㎂, 0.5 V)

Qualitative analysis was performed by conducting an initial survey scan on the surface of the sample subject to analysis in the as-received state under the following conditions, and quantitative analysis was performed through narrow scan (snap) for each element according to the results of the qualitative analysis. The ratio of elements in three locations for each sample was confirmed, and the peak background smart method was applied for quantitative analysis. The binding energy correction of the core level spectrum was based on C 1s (284.8 eV).

<Survey scan conditions>

- Scan section binding energy: -5 ~ 1350 eV

- Step size: 1 eV

- Per Point dwell time: 20 ms

-Periods: 2

- Pass energy: 200 eV

<narrow scan conditions>

- Scan section binding energy: about 20 eV

- Step size: ~ 0.16 eV

- Per Point dwell time: 1 sec

- Periods: 10~30

- Pass energy: 150 eV

<Etching conditions>

- Source: Ar ion

- Energy: 6 keV

- Cluster size: 75

-Rater size: ^1.6

-Mode: GCIB

All photopolymer compositions prepared in the Examples and Comparative Examples included the polymer matrix, photoreactive monomer, and fluorine-based compound, which account for the largest proportion of the solid content, at 25 g, 52 g, and 23 g, respectively, and were composed of polymer matrix: photoreactive monomer: The weight ratio of the fluorine-based compounds was all 25:52:23.

As a result, the element ratios of all samples prepared in the examples and comparative examples were 62.1 atomic% for carbon, 0.9 atomic% for nitrogen, 21.0 atomic% for oxygen, 6.2 atomic% for fluorine, and 9.8 atomic% for silicon.

In addition, as a result of measuring the element ratios on the surface of the sample before and after recording, the element ratios on the surface of the sample before and after recording were measured to be the same.

(2) Calculation of reaction energy

To calculate the reaction energy E2 in Scheme 1 below, the lowest singlet excitation energy (S1) of the borate anion (BX1 The lowest triplet excitation energy (T1) was obtained. Using density functional theory (DFT), S1 and T1 were calculated for the optimized structure using B3LYP as the functional and 6-31G* as the basis function.

Since the photosensitive dye undergoes an electron reduction reaction, T1 is written as a negative value, and since the electron donor undergoes an electron oxidation reaction, S1 is written as a positive value, and the total reaction energy E2 is calculated by adding these.

[Scheme 1]

T1 of photosensitive dye Types of Electron Donors S1 of electron donor Reaction energy (E2) Example 1 -465.4 kJ/mol Hexadecyl dimethyl benzyl ammonium tri(p-chlorophenyl)butyl borate +456.9 kJ/mol -8.5 kJ/mol Example 2 -465.4 kJ/mol Hexadecyl Benzyl Pyrrolidinium Tri(p-Chlorophenyl)Butyl Borate +456.9 kJ/mol -8.5 kJ/mol Comparative Example 1 -465.4 kJ/mol WPBG-300 (1,2-dicyclohexyl-4,4,5,5-tetramethylbiguanidium tri(phenyl)butyl borate) +435.3 kJ/mol -30.1 kJ/mol Comparative Example 2 -465.4 kJ/mol WPBG-300 +435.3 kJ/mol -30.1 kJ/mol Comparative Example 3 -465.4 kJ/mol Tetrabutyl ammonium tri(o-methylphenyl)hexyl borate +399.1 kJ/mol -66.3 kJ/mol

Test Example 2: Performance evaluation of hologram recording medium

(1) Thermal stability (△T)

Thermal stability was evaluated as the lowest transmittance change (△T) before and after exposure to high temperature. Specifically, the thermal stability was evaluated based on the lowest degree of change in transmittance after recording the diffraction grating on the pre-recording sample that was not exposed to high temperature and the pre-recording sample that was exposed to high temperature, and the lowest degree of change in transmittance was obtained through Equation 1 below.

[Equation 1]

△T(%) = {(│T1 - T0│)/ T0}

In Equation 1, T0 is obtained by storing the sample in a dark room under constant temperature (20 to 25 ℃) and constant humidity (relative humidity of 40 to 50%) conditions before recording, and then using a UV-Vis spectrometer for the sample on which the notch filter hologram was recorded. It is the lowest transmittance measured in the wavelength range of 300 to 1,200 nm, and T1 is the same as the above method for the sample on which the notch filter hologram was recorded after storing the sample before recording for 100 hours in a dark room at 60 ℃ and 40 to 50% relative humidity conditions. This is the lowest transmittance measured.

The notch filter hologram was recorded using the same setup as shown in Figure 1. Specifically, when the manufactured photopolymer layer is laminated on a mirror and then irradiated with a laser, a notch filter hologram with periodic refractive index modulation in the thickness direction is generated through interference between incident light (L) and light reflected from the mirror (L'). This can be recorded. In this example, the notch filter hologram was recorded with an incident angle of 0 ° (degree). Notch filters and Bragg reflectors are optical elements that reflect only light of a specific wavelength, and have a structure in which two layers with different refractive indices are stacked periodically and repeatedly at a certain thickness.

(2) Diffraction efficiency (DE)

Diffraction efficiency (η) was obtained through Equation 2 below for the sample on which the notch filter hologram was recorded in the above-described manner.

[Equation 2]

η(%) = {P _D / (P _D + P _T )}

In Equation 2, η is the diffraction efficiency, P _D is the output amount of the diffracted beam of the sample after recording (mW/cm2), and P _T is the output amount of the transmitted beam of the sample after recording (mW/cm2).

Reaction energy (E2) Thermal stability (△T, %) Diffraction efficiency (DE, %) Example 1 -8.5 kJ/mol 0.8 98.0 Example 2 -8.5 kJ/mol 2.2 91.5 Comparative Example 1 -30.1 kJ/mol 78 92.1 Comparative Example 2 -30.1 kJ/mol 92.8 89.2 Comparative Example 3 -66.3 kJ/mol 100 96.4

Referring to Table 3, the hologram recording medium has better stability over time at high temperatures before recording as it uses an electron donor with a reaction energy of -25 to 0 kJ/mol with the photosensitive dye excited in the triplet state. It is confirmed that the diffraction efficiency, which is a general physical property of the hologram recording medium, is also very excellent.

In addition, it was confirmed that Example 1, which additionally included an electron acceptor, exhibited superior high temperature stability over time compared to the remaining Examples and Comparative Examples that did not include the electron acceptor.

Claims (10)

An anion represented by Formula 1 below; and a cation represented by Formula 2 below,
Activated by light irradiation to cause photopolymerization of photoreactive monomers dispersed in a polymer matrix, used to record optical information,
compound:
[Formula 1]

In Formula 1,
R ¹⁰² is each independently hydrogen, an alkyl group or halogen, and at least one of R ¹⁰² is halogen,
R ¹⁰³ is each independently hydrogen, an alkyl group, or halogen, but when the adjacent R ¹⁰² is hydrogen or an alkyl group, it is halogen,
R is an alkyl group having 1 to 24 carbon atoms.
[Formula 2]
NY ¹ Y ² Y ³ Y ⁴
In Formula 2, two substituents of Y ¹ to Y ⁴ may or may not be connected to each other to form an aliphatic ring having 4 to 10 carbon atoms,
Y ¹ to Y ⁴ that do not form an aliphatic ring are each independently an alkyl group with 1 to 40 carbon atoms, an aryl group with 6 to 30 carbon atoms, an arylalkyl group with 6 to 40 carbon atoms, or an alkyl group with 2 to 40 carbon atoms linked through an ester bond. become,
It is excluded that Y ¹ to Y ⁴ are all methyl groups or that two or more substituents are alkyl groups having 16 or more carbon atoms.
According to claim 1,
A compound in which two of R ¹⁰² are halogens.
According to claim 1,
R ¹⁰² A compound in which all are halogens.
According to claim 1,
In Formula 2, at least one of Y ¹ to Y ⁴ is an aryl group.
According to claim 1,
A compound in which two substituents of Y ¹ to Y ⁴ in Formula 2 are connected to each other to form piperidine or pyrrolidine.
According to claim 1,
The polymer matrix is a polymer matrix formed by crosslinking a siloxane-based polymer containing a silane functional group and a (meth)acrylic polyol.
According to claim 1,
The photoreactive monomer is a compound having at least one photoreactive group selected from a (meth)acryloyl group, a vinyl group, and a thiol group.
The compound according to any one of claims 1 to 7, which is an electron donor; And a light-sensitive dye,
Activated by light irradiation to cause photopolymerization of photoreactive monomers dispersed in a polymer matrix, used to record optical information,
Photopolymerization initiator system.
According to claim 8,
Further comprising one or more selected from onium salt compounds and triazine compounds as an electron acceptor,
Photopolymerization initiator system.
A polymer matrix formed by crosslinking a siloxane-based polymer containing a silane functional group and a (meth)acrylic-based polyol;
Photoreactive monomer; and
Comprising a compound according to claim 1 or said photoinitiator system according to claim 8,
Composition.