JPWO2014030533A1 - Method for producing circularly polarizing body and circularly polarizing body - Google Patents

Abstract

It is an object of the present invention to provide a method for producing a circularly polarizing body and a circularly polarizing body that exhibit circular dichroism at an arbitrary wavelength and exhibit circular dichroism having different polarities depending on the incident direction of light. To do. The present invention is a method for producing a circularly polarizing body by forming a first film containing a chiral substance and forming a second film containing a light-absorbing substance on the first film. The circularly polarizing body of the present invention is characterized by comprising a first film containing a chiral substance and a second film containing a light-absorbing substance disposed on the first film. A biomolecule selected from saccharides, tartaric acid, vitamins, peptides, and proteins may be used as the chiral substance. As the light absorbing substance, a low molecular weight light absorbing substance such as rhodamine 6G or Nile blue can be used.

Description

  The present invention relates to a method of manufacturing a circularly polarizing body and a circularly polarizing body applicable to optical elements used in optical isolators, optical fibers, liquid crystal displays, and the like.

  When a real image and a mirror image of a substance cannot be superimposed, the substance is said to be chiral, and this property is called chirality. A substance having chirality exhibits circular dichroism (CD) in which there is a difference in absorbance between counterclockwise circularly polarized light and clockwise circularly polarized light. Since such a circular dichroism phenomenon occurs at a wavelength peculiar to the material, a polarization-dependent optical isolator having a function of transmitting only a circularly polarized light having a specific wavelength and blocking a circularly polarized light in the reverse direction. The present invention can be applied to such optical devices and optical elements used in optical fibers, liquid crystal displays, and the like. It can also be used in a circular dichroism measuring apparatus that irradiates molecules with circularly polarized light of a specific wavelength and analyzes the three-dimensional structure of the molecules.

  Many biomolecules typified by proteins, amino acids, and saccharides are known to have chirality. Many of these biomolecules exhibit circular dichroism with respect to light in the ultraviolet region, but do not exhibit circular dichroism with respect to light in the visible region. Therefore, in such biomolecules, studies have been made to develop circular dichroism at a wavelength in the visible region different from the wavelength at which the biomolecule exhibits circular dichroism.

  For example, Non-Patent Document 1 reports that circular dichroism appears in the visible region, which is the absorption wavelength of localized surface plasmons of gold fine particles, by mixing riboflavin, which is a biomolecule having chirality, with gold fine particles. Has been. In Non-Patent Document 1, a mixture of gold microparticles and riboflavin is formed by irradiating ultraviolet curable resin with chloroauric acid (III) ions mixed with UV-curable resin together with riboflavin, which is a biomolecule having chirality. . When the circular dichroism (CD) spectrum was measured by irradiating this mixed film with circularly polarized light in the ultraviolet-visible region, a CD peak was observed in the vicinity of 550 nm which is the absorption wavelength of the gold fine particles (see FIG. 3).

Yuka Kosaka, Kazue Egami, Tomoshi Hamada, Hisao Yanagi “Plasmonic Circular Dichroism with Gold Fine Particles and Riboflavin” 2012 Proceedings of the Japan Society of Applied Physics, March 17, 2012, 17a-B11-9

  In the above-mentioned mixed film of riboflavin and gold fine particles, a CD peak having the same polarity is seen regardless of the incident direction of circularly polarized light. For example, the optical isolator is an optical device having a function of transmitting only light from one direction and blocking light in the opposite direction. However, in such an optical device, the above-described mixed film cannot be used.

  The problem to be solved by the present invention is to provide a method for producing a circularly polarizing body and a circularly polarizing body that exhibit circular dichroism at an arbitrary wavelength and exhibit circular dichroism having different polarities depending on the incident direction of light. Is to provide.

  The method for producing a circularly polarizing body according to the present invention is characterized in that a first film containing a chiral substance is formed, and a second film containing a light absorbing substance is formed on the first film.

  In addition, the circularly polarizing body according to the present invention includes a first film containing a chiral substance and a second film containing a light-absorbing substance disposed on the first film.

Here, the chiral substance means a substance having a property as a chiral medium itself, or a substance having a property as a chiral medium when mixed with another substance. That is, the first film has a property as a chiral medium by containing a chiral substance. There are various kinds of such chiral substances. For example, biomolecules such as sugars, tartaric acid, vitamins, peptides, and proteins can be used.
Similarly, the light-absorbing substance refers to a substance having a property as a light-absorbing medium by mixing with another substance in addition to a substance having a property as a light-absorbing medium itself. That is, the second film has a property as a light absorbing medium by containing the light absorbing substance. There are various kinds of such light-absorbing substances. For example, low-molecular substances such as rhodamine 6G and Nile Blue may be used.

  In the present invention, when a light-absorbing substance that absorbs at a wavelength different from the wavelength at which the chiral substance exhibits circular dichroism (CD) is combined, the circularly-polarized light can be obtained even at the absorption wavelength of the light-absorbing substance. It has been found that it exhibits chromaticity, and further, a first film containing a chiral substance and a second film containing a light-absorbing substance are laminated to form an interface between the chiral medium and the light-absorbing medium. It was made as a result of finding that it showed antisymmetric circular dichroism which was not seen in the mixed film of the light-absorbing substance. Here, the antisymmetric circular dichroism is the CD peak between when the circularly polarized light is incident from one side of the first film and the second film and when the circularly polarized light is incident from the other side. It means that the polarity is reversed.

  The first film may be composed of a light-transmitting polymer containing a chiral substance. Similarly, the second film may be composed of a light-transmitting polymer containing a light-absorbing substance. It is preferable to use a photocurable resin for the light-transmitting polymer.

  The second film may contain a plurality of types of light-absorbing substances having different absorption wavelengths. Further, the second film is composed of a laminated film formed by laminating a plurality of films containing a light-absorbing substance, and the absorption wavelength of the light-absorbing substance contained in each film of the laminated film is different from each other. It may be configured. Furthermore, the first film may contain a light-absorbing substance having an absorption wavelength different from that of the light-absorbing substance contained in the second film. According to such a configuration, it is possible to obtain a circularly polarizing body that exhibits circular dichroism at a plurality of wavelengths.

  According to the present invention, by forming the second film using a light-absorbing substance having an appropriate absorption wavelength, a circularly polarizing body that exhibits circular dichroism at a target wavelength can be obtained. Further, in the circular polarizer according to the present invention, the CD response polarity is inverted when light is incident from the first film side and when light is incident from the second film side. Therefore, it can be used as a circularly polarized light control element having a different polarity depending on the incident direction of light, such as an optical isolator.

The figure which shows schematically the manufacturing method of the circularly-polarizing body of this invention. Explanatory drawing of circular dichroism. Absorption spectrum (a) and CD spectrum (b) of a film containing only riboflavin (Comparative Example 1) and a mixed film circular polarizer of Reference Example 1 of riboflavin and gold fine particles. CD spectrum (a) and absorption spectrum (b) of a film containing only rhodamine 6G (Comparative Example 2) and a mixed film circular polarizer of Rhodamine 6G and D glucose (Reference Example 2). CD spectrum (a) and absorption spectrum (b) of a film containing only rhodamine 6G (Comparative Example 2) and a mixed film circular polarizer of Rhodamine 6G and L glucose (Reference Example 2). CD spectrum (a) and absorption spectrum (b) when light is incident from one direction and the other direction on a mixed film circularly polarizing body (Reference Example 2) using D / L glucose and rhodamine 6G. CD spectrum (a) and absorption spectrum (b) when light is incident from one direction and the other direction on a mixed film circularly polarizing body (Reference Example 3) using D / L tartaric acid and rhodamine 6G. CD spectrum and absorption spectrum (a) of a mixed film circular polarizer (Reference Example 2) using D glucose and rhodamine 6G, and CD spectrum of a mixed film circular polarizer (Reference Example 4) using D glucose and Nile blue And absorption spectrum (b). The figure which shows schematic structure of the multilayer film circularly-polarizing body which concerns on this invention. The CD spectrum (a) and absorption spectrum (b) when light is incident on the multilayer circularly polarizing body using D / L glucose and rhodamine 6G according to Example 1 of the present invention from one direction and the other direction. The CD spectrum (a) and absorption spectrum (b) when light is incident on the multilayered circular polarizer using D glucose and rhodamine 6G according to Example 2 of the present invention from one direction and the other direction. The CD spectrum (a) and absorption spectrum (b) when light is incident on the multilayer circularly polarizing body using L glucose and Rhodamine 6G according to Example 2 of the present invention from one direction and the other direction.

  As described above, the present invention is triggered by the discovery of a phenomenon that exhibits circular dichroism at the absorption wavelength of the light-absorbing substance in the mixed film of the chiral substance and the light-absorbing substance. Therefore, in the following, as a reference example, a circularly polarizing body composed of a mixed film containing both a chiral substance and a light-absorbing substance (hereinafter referred to as “mixed-film circularly polarizing body”) will be described first, and then a chiral substance will be described. An example of a circularly polarizing body (hereinafter referred to as “multilayered circularly polarizing body”) formed by laminating a first film containing a substance and a second film containing a light-absorbing substance will be described.

  FIG. 1 shows a method for producing a mixed film circular polarizer. First, a light-absorbing substance and a chiral substance are mixed with a colorless and transparent ultraviolet curable resin (PAK-01, manufactured by Toyo Gosei Co., Ltd.), and this mixture is applied to a quartz substrate which is a light-transmitting substrate. In this embodiment, an ultraviolet curable resin is used as the translucent polymer, but a thermosetting resin may be used. The type of resin is not particularly limited as long as it does not hinder the measurement of circular dichroism described below.

  Next, another quartz substrate is pressed onto the mixture on the quartz substrate, and the mixture is cured by irradiation with ultraviolet light. As a result, a mixed film circular polarizer having a structure in which a mixed film of a light absorbing material and a chiral material is sandwiched between two quartz substrates is formed.

  Subsequently, in order to evaluate the circular dichroism of the mixed film circular polarizer, clockwise and counterclockwise circularly polarized light is incident from one quartz substrate side of the mixed film circular polarizer (FIG. 2), and an absorption spectrum is obtained. And circular dichroism (CD) spectra were measured.

<Reference Example 1>
Comparative Example 1 in which a coating film formed by blending only a riboflavin, which is a chiral substance, with an ultraviolet curable resin (PAK-01) is sandwiched between two quartz substrates, and chloroauric acid (III ) Mixed film circular polarizers (Reference Example 1) using ions and riboflavin as a chiral substance were prepared, and their absorption spectrum (UV-vis spectrum) and CD spectrum were measured.
In Comparative Example 1, 2.0 mg of riboflavin was added to 1000 mg of the ultraviolet curable resin.
In Reference Example 1, 2.0 mg of riboflavin and 22.5 mg of chloroauric acid (III) were blended with respect to 1000 mg of the ultraviolet curable resin.
The ultraviolet irradiation time for curing the ultraviolet curable resin and reducing chloroauric acid (III) was 40 minutes.
FIG. 3A shows the measurement result of the absorption spectrum, and FIG. 3B shows the measurement result of the CD spectrum.
As is apparent from FIG. 3, in Reference Example 1, light absorption was observed near the wavelength of 550 nm, and similarly, a CD peak was observed near the wavelength of 550 nm. On the other hand, in Comparative Example 1, neither an absorption spectrum nor a CD spectrum was observed.

<Reference Example 2>
Comparative Example 2 in which a coating film formed by mixing only rhodamine 6G, which is a light-absorbing substance, with UV curable resin (PAK-01) is sandwiched between two quartz substrates, and D / L glucose, which is a chiral substance. And a rhodamine 6G mixed film circular polarizer (Reference Example 2), and their absorption spectrum (UV-vis spectrum) and CD spectrum were measured. Rhodamine 6G is an organic fluorescent dye having an absorption peak near a wavelength of 540 nm.
In Comparative Example 2, 3.2 mg of rhodamine 6G was added to 200 mg of the ultraviolet curable resin.
In Reference Example 2, 3.2 mg of rhodamine 6G and a solution obtained by adding 20.0 mg of D / L glucose to 40.0 μL of distilled water were mixed with 200 mg of the ultraviolet curable resin.
The ultraviolet irradiation time for curing the ultraviolet curable resin was 5 minutes.
FIGS. 4A and 4B show the measurement results of the absorption spectrum and CD spectrum when D glucose is used, and FIGS. 5A and 5B show the absorption spectrum and CD spectrum when L glucose is used. The measurement results are shown.

  As can be seen from FIGS. 4 and 5, in Comparative Example 2 containing only rhodamine 6G, a peak was observed in the absorption spectrum, but no peak was observed in the CD spectrum. On the other hand, in Reference Example 2 of the mixed film circular polarizer containing rhodamine 6G and D / L glucose, peaks were observed in both the absorption spectrum and the CD spectrum, and both peak wavelengths were substantially the same. Moreover, the polarity of the CD peak was inverted between D glucose and L glucose.

  The gold fine particles used in Reference Example 1 are substances that exhibit localized plasmon mode light absorption, and Rhodamine 6G used in Reference Example 2 is a substance that exhibits light absorption that causes fluorescence emission. Therefore, although both have different light absorption mechanisms, it has been found that in any case, a CD peak is expressed by mixing with a chiral substance.

  Next, when light is incident from one quartz substrate side and light is incident from the other quartz substrate side to the mixed-film circular polarizer (Reference Example 2) containing rhodamine 6G and D / L glucose The absorption spectrum and CD spectrum were measured. The result is shown in FIG. As can be seen from FIGS. 6 (a) and 6 (b), the CD peak having the same polarity was observed regardless of the incident direction of light when either D glucose or L glucose was used.

<Reference Example 3>
In order to investigate the change in the CD peak due to the difference in the chiral substance, a mixed film circular polarizer (Reference Example 3) using D / L tartaric acid instead of D / L glucose of Reference Example 2 was prepared. The absorption spectrum and CD spectrum were measured when light was incident on 3 from one quartz substrate side and when light was incident from the other quartz substrate side. The same rhodamine 6G as in Reference Example 2 was used as the light absorbing material. The amount of the UV curable resin, rhodamine 6G used in Reference Example 3 was the same as in Reference Example 2. Furthermore, the amount of D / L tartaric acid used in Reference Example 3 was the same as the amount of D / L glucose used in Reference Example 2.
FIG. 7 shows the result. As can be seen from the comparison between FIG. 6 and FIG. 7, in any mixed film circular polarizer, a CD peak was observed at 540 nm, which is the absorption wavelength of rhodamine 6G. From this, even if the kind of chiral substance is different, when a light absorbing substance is mixed, a CD peak is observed at the absorption wavelength of the light absorbing substance, that is, the CD peak wavelength of the chiral substance itself is absorbed by light. It was found that the influence on the newly developed CD peak wavelength was small by mixing the active substance.

<Reference Example 4>
Next, in order to investigate the change in CD peak due to the difference in the light-absorbing substance, a reference example of a mixed film circular polarizer in which Nile blue as a light-absorbing substance is blended with an ultraviolet curable resin together with D-glucose as a chiral substance 4 was prepared, and the absorption spectrum and CD spectrum of Reference Example 4 were compared with Reference Example 2 described above (a mixed film circular polarizer containing rhodamine 6G and D glucose).
Reference Example 4 was prepared in the same manner as Reference Example 2 except that Nile Blue was used instead of Rhodamine 6G.
The result is shown in FIG. FIG. 8A shows the result of using rhodamine 6G, and FIG. 8B shows the result of using Nile blue, but the CD peak wavelength was different between the two. From the above results, it was found that the CD peak wavelength of the mixed film circular polarizer changes depending on the absorption wavelength of the light-absorbing substance mixed with the chiral substance.

Based on the results of the mixed film circular polarizer, a multilayer circular polarizer was prepared and the properties thereof were investigated. This will be described in detail below. As shown in FIG. 9, in the multilayered circular polarizer described in the following examples, a laminate of a first film that is a chiral medium and a second film that is a light absorbing medium is sandwiched between a pair of quartz substrates. It has a configuration.
<Example 1>
D / L glucose, which is a chiral substance, is mixed with an ultraviolet curable resin (PAK-01) and applied to a quartz substrate to form a first coating layer. The first coating layer is cured by irradiation with ultraviolet rays. One film was formed. Thereafter, a second coating layer is formed on the first film by applying a mixture of rhodamine 6G, which is a light-absorbing substance, to an ultraviolet curable resin, and another quartz substrate is pressed thereon to emit ultraviolet light. The second coating layer was cured by irradiation to form a second film. As a result, a multilayered circular polarizer having a laminated structure composed of the first film and the second film was obtained between the two quartz substrates.
In the first film of the multilayer circularly polarizing body according to Example 1, rhodamine 6G3.2 mg was blended with 200 mg of the ultraviolet curable resin. The 2nd film | membrane mix | blended the solution which added 40.0 microliters of distilled water to 20.0 mg of D-glucose with respect to 200 mg of ultraviolet curable resins.
In either case, the ultraviolet curable resin was cured by irradiation with ultraviolet rays for 5 minutes.

  Light was incident on the multilayer circular polarizer thus produced from the first film side and the second film side, and the absorption spectrum and CD spectrum were measured. The result is shown in FIG. The upper part (a) of FIG. 10 shows the CD spectrum, and the lower part (b) shows the absorption spectrum. As can be seen from FIG. 10 (b), the absorption peak of the multilayered circular polarizer was observed in the vicinity of the wavelength of 540 nm, which is the absorption peak of rhodamine 6G. In addition, the CD peak of the multilayer circular polarizer was also observed in the vicinity of the wavelength of 540 nm, which is the absorption peak of rhodamine 6G. Further, in the multilayer circular polarizer using L glucose as the chiral substance contained in the first film and the multilayer circular polarizer using D glucose, the CD peak polarity is reversed, and the first film side The polarity of the CD peak was inverted when the light was incident from (shown as “GtoR” in FIG. 10) and when it was incident from the second film side (shown as “RtoG” in FIG. 10).

  As described above, in the multilayered circular polarizer, the CD peak wavelength can be adjusted by using a light-absorbing substance having an appropriate absorption wavelength, and the optical turning property (chirality) of the chiral substance or the incident direction of light Thus, it was found that the polarity of the CD peak of the multilayered circular polarizer can be adjusted.

<Example 2>
D / L glucose, which is a chiral substance, was dissolved in ethanol, applied to a quartz substrate and dried to form a first film, and then rhodamine 6G was mixed with UV curable resin (PAK-01) on the first film. The thing was apply | coated and the 2nd application layer was formed. Then, another quartz substrate is pressed onto the second coating layer, and the second coating layer is cured by irradiating ultraviolet rays to form a second film, and the first film and the second film are formed between the two quartz substrates. A multilayered circular polarizer having a laminated structure consisting of
The first film of the multilayered circular polarizer according to Example 2 is made of a saturated solution obtained by adding 1 mL of ethanol to 100 mg of D / L glucose. In the second film, 3.2 mg of rhodamine 6G was blended with 200 mg of the ultraviolet curable resin. The ultraviolet irradiation time for curing the ultraviolet curable resin of the second film was 5 minutes.

  Light was incident on the multilayer circular polarizer thus produced from the first film side and the second film side, and the absorption spectrum and CD spectrum were measured. The results are shown in FIGS. 11 and 12, the upper part (a) shows the CD spectrum, and the lower part (b) shows the absorption spectrum. Similar to Example 1, also in Example 2, the absorption peak and CD peak of the multilayered circular polarizer were found near the wavelength of 540 nm, which is the absorption peak of rhodamine 6G. Further, when the light is incident from the first film side (indicated by “GtoR” in FIGS. 11 and 12) and when the light is incident from the second film side (indicated by “RtoG” in FIGS. 11 and 12). In each case, the polarity of the CD peak was reversed.

In addition, this invention is not limited to an above-described Example, For example, the following modifications are possible.
In the above embodiment, the first film and the second film are sandwiched between a pair of quartz substrates. However, a glass substrate, a resin substrate, or the like may be used as long as the material transmits light. Moreover, you may comprise a multilayer-film circularly-polarizing body only with a 1st film | membrane and a 2nd film | membrane.
The second film may contain a plurality of types of light-absorbing substances having different absorption wavelengths. Further, the first film may contain both a chiral substance and a light absorbing substance. In this case, the first film may contain a light-absorbing substance having a light absorption wavelength different from that of the light-absorbing substance contained in the second film.

Claims (17)

  A method of manufacturing a circularly polarizing body by forming a first film containing a chiral substance and forming a second film containing a light-absorbing substance on the first film.   The method for producing a circularly polarizing body according to claim 1, wherein the first film is made of a translucent polymer containing a chiral substance.   The method for producing a circularly polarizing body according to claim 1, wherein the second film is made of a light-transmitting polymer containing a light-absorbing substance.   The method for producing a circularly polarizing body according to claim 2, wherein the translucent polymer is a photocurable resin.   The said 2nd film | membrane contains the multiple types of light absorptive substance from which absorption wavelength differs, The manufacturing method of the circularly-polarizing body in any one of Claims 1-4 characterized by the above-mentioned. The second film is formed of a laminated film in which a plurality of films containing a light-absorbing substance are laminated on the first film;
The method for producing a circularly polarizing body according to any one of claims 1 to 4, wherein the absorption wavelengths of the light-absorbing substances contained in each of the laminated films are different from each other.   The circle according to any one of claims 1 to 4, wherein the first film further contains another light-absorbing substance having an absorption wavelength different from that of the light-absorbing substance contained in the second film. A method for producing a polarizer.   A circularly polarizing body comprising a first film containing a chiral substance and a second film containing a light absorbing substance disposed on the first film.   The circularly polarized light body according to claim 8, wherein the first film and the second film are disposed between a pair of translucent substrates.   10. The circularly polarized light body according to claim 8, wherein the first film is made of a translucent polymer containing a chiral substance.   The circularly polarizing body according to any one of claims 8 to 10, wherein the second film is made of a light-transmitting polymer containing a light-absorbing substance.   The circularly polarizing body according to claim 10 or 11, wherein the translucent polymer is a photocurable resin.   The circularly polarizing body according to any one of claims 8 to 12, wherein the second film contains a plurality of kinds of light-absorbing substances having different absorption wavelengths. The second film is formed of a laminated film in which a plurality of films containing a light-absorbing substance are laminated on the first film;
The circularly polarized light body according to any one of claims 8 to 12, wherein the absorption wavelengths of the light-absorbing substances contained in each of the laminated films are different from each other.   The circle according to any one of claims 8 to 12, wherein the first film further contains another light-absorbing substance having an absorption wavelength different from that of the light-absorbing substance contained in the second film. Polarizer.   The circularly polarized light body according to any one of claims 8 to 15, wherein the chiral substance is a biomolecule selected from sugars, tartaric acid, vitamins, peptides, and proteins.   The circularly polarizing body according to any one of claims 8 to 16, wherein the light absorbing substance is rhodamine 6G or Nile blue.