JP5028626B2 - Fluorescent material - Google Patents

Description

  The present invention relates to a fluorescent material. The fluorescent material of the present invention has excellent heat resistance and exhibits a fluorescence emission spectrum over a wide visible wavelength range, and can be used as a material for a light emitting device that exhibits white or high whiteness emission color.

  In recent years, various low molecular weight compounds and polymer compounds have been developed as organic light emitting materials used for organic electroluminescence (EL) elements, light emitting spatial light modulation elements, wavelength conversion elements and the like. In the production of light emitting devices and the like, when using a low molecular compound, the production process is almost restricted to the vacuum deposition method, whereas the polymer compound can be produced as a solution state by film formation or an inkjet printing method, The manufacturing cost can be reduced. In addition, the polymer compound has excellent features such as the ability to perform minute coating without fine processing and the ability to easily form a thick film. Therefore, it is desired to develop a high-molecular light-emitting material that exhibits high-efficiency fluorescence and can easily control the emission wavelength.

  As polymer light-emitting materials, π-conjugated polymers such as poly-p-phenylene and polyphenylene vinylene are known. However, such a π-conjugated polymer has a problem that heat resistance and environmental resistance (chemical stability) are not sufficient, and film formation and microfabrication are not easy. On the other hand, polyimide, which is a typical heat-resistant polymer, has excellent heat resistance and electrical properties, and the precursor polyamic acid has excellent processability such as film formation. Use as a material is expected. For example, Non-Patent Document 1 discloses a polyimide exhibiting blue fluorescent light emission in which a fluorescent furyl group is introduced into the main chain or side chain, and Patent Document 1 and Patent Document 2 disclose light emission. An organic EL element using a polyimide having a function or a charge transport function is disclosed. However, the fluorescence emission of polyimide disclosed in the above patent document and non-patent document is due to the fluorescent functional group introduced into the main chain or side chain of the polyimide, and the fluorescence intensity is between polyimide molecules. Due to the strong interaction and the accompanying disappearance of concentration, the fluorescence intensity is very low compared to the fluorescence intensity of the low-molecular compound having the same fluorescent functional group.

  In addition, as disclosed in Non-Patent Document 2 and the like, it has been conventionally known that polyimide itself exhibits visible fluorescence by irradiation with ultraviolet rays. This fluorescence is fluorescence (CT fluorescence) resulting from a charge transfer complex (CTC) formed between a diamine portion (electron donating property) and an acid anhydride portion (electron attracting property) in the molecular structure of polyimide. (For example, refer nonpatent literature 3.). However, in the case of aromatic polyimide, the CT interaction becomes strong and the non-radiation deactivation process increases, so the fluorescence intensity becomes weak. In a polyimide (PMDA / ODA) synthesized from pyromellitic anhydride, which is a typical wholly aromatic polyimide film, and 4,4′-diaminodiphenyl ether, weak fluorescence that is difficult to observe with a normal fluorescence spectrometer Only observed. Further, Non-Patent Document 4 reports that polyimide (BPDA / PDA) synthesized from biphenyltetracarboxylic anhydride and paraphenylenediamine exhibits relatively strong fluorescence even in wholly aromatic polyimide. However, compared to existing fluorescent compounds, the fluorescence intensity is very weak and the quantum yield is considered to be 1% or less.

  Patent Document 3 uses a polyimide having a three-dimensional structure and having a structural unit composed of an aromatic dianhydride having fluorine directly bonded to an aromatic ring and a diamine having an alicyclic structure. In addition to excellent fluorescence emission characteristics (intensity of fluorescence intensity, controllability of fluorescence wavelength in the green to red range, long-term stability of fluorescence intensity), it also has excellent heat resistance, chemical stability, and film formability It is disclosed that a fluorescent polyimide is obtained. In addition, Non-Patent Document 5 is superior in that it has a three-dimensional structure and uses a polyimide having a structural unit composed of an acid dianhydride having a low electron accepting property and a diamine having an alicyclic structure. It is disclosed that a fluorescent polyimide having blue fluorescent emission characteristics and excellent in heat resistance, chemical stability, and film forming property can be obtained. The fluorescent polyimides disclosed in Patent Document 3 and Non-Patent Document 5 have strong fluorescence intensity, but are basically monochromatic.

S. M. Pyo et al., Polymer, 40, 125-130 (1999) Japanese Patent Laid-Open No. 03-274663 Japanese Patent Laid-Open No. 04-93389 E. D. Wachsman and C. W. Frank Polymer, 29, 1191-1197 (1988) M. Hasegawa and K. Horie, Progress in Polymer Science, 26, 259-335 (2001) M. Hasegawa et al., Journal of Polymer Science Part C: Polymer Letters, 27, 263-269 (1998) JP 2004-307857 A H. Sekino et al., Proceedings of the Society of Polymer Science, 53, 1543 (2004).

Whiteness is required for lighting applications, display backlights, and the like, and such whiteness can be obtained by combining fluorescent emission corresponding to the three primary colors of light (blue, green, red). . However, since different types of fluorescent polyimides are not necessarily compatible with each other, they cannot be easily combined, and forming a film by stacking three layers makes the process complicated. As a result, in order to obtain white light emission, it is expected that single layer polyimide emits white fluorescent light with a high quantum yield.
Therefore, the object of the present invention is a white having excellent fluorescence emission characteristics (fluorescence intensity, long-term stability of fluorescence intensity) with high whiteness, and excellent heat resistance, chemical stability, and film-forming property. It is to provide a fluorescent material.

  As a result of intensive studies to achieve the above object, the present inventors have obtained the knowledge that a polyimide composed of a specific repeating unit can achieve the above object, and the results of intensive investigation based on the knowledge The present invention has been completed.

  The present invention has been made on the basis of the above knowledge, and is a repeating unit represented by the following general formula (1), wherein the repeating unit has a repeating unit having a fluorescence peak at 380 to 520 nm. The present invention provides a fluorescent material containing a polyimide having a repeating unit represented by the general formula (2), wherein the polyimide comprising the repeating unit has a repeating unit having a fluorescence peak at 560 to 760 nm.

(In the formula, R ¹ represents a tetravalent aromatic group represented by the following general formula (3) or the following general formula (4), and R ² represents a divalent organic group containing an alicyclic structure. )

(In the formula, R ² represents a divalent organic group containing an alicyclic structure, and R ³ represents a tetravalent aromatic group represented by the following general formula (5).)

(In the formula, R ⁴ is an aliphatic group optionally substituted with halogen, an oxygen atom, an aromatic group via one or more divalent elements, or a combination thereof. (It represents a divalent substituent or a single bond.)

(In the formula, R ⁴ and R ⁵ may be the same or different, and may be an aliphatic group optionally substituted with halogen, an oxygen atom, or an aromatic group via one or more divalent elements. Or a single bond formed by a combination thereof.)

  (In the formula, X and Y may be the same or different, and are either an aliphatic group which may be substituted with halogen, an aromatic group via one or more divalent elements, or halogen. Or a divalent substituent constituted by a combination thereof.

As a suitable example of the repeating unit constituting the polyimide contained in the fluorescent material of the present invention, R ¹ in the general formula (1) is an fragrance selected from the group consisting of the following formulas (6) to (14). The group which is a group is mentioned.

As the repeating units constituting the polyimide contained in the fluorescent material of the present invention, R ² in the general formula (1) and (2) may be mentioned those which are alicyclic alkyl group.
As the repeating units constituting the polyimide contained in the fluorescent material of the present invention, R ² in the general formula (1) and (2) is selected from the group consisting of the following formulas (15) - (18) Can be mentioned.

As the repeating units constituting the polyimide contained in the fluorescent material of the present invention, R ³ in the general formula (2) may be mentioned those that are formula (19).

  Moreover, this invention provides the organic light emitting device manufactured using the said fluorescent material. Examples of the organic light emitting device include an organic EL element, an organic laser, and a spatial light modulation element.

  According to the present invention, a white fluorescent material having a high whiteness and excellent fluorescent emission characteristics, excellent heat resistance and film forming property, and low water absorption is provided.

Hereinafter, the fluorescent material of the present invention will be described in detail.
The fluorescent material of the present invention is a repeating unit represented by the following general formula (1), and the polyimide comprising the repeating unit is represented by a repeating unit having a fluorescence peak at 380 to 520 nm and the following general formula (2). It is a repeating unit, The polyimide which consists of this repeating unit contains the polyimide which has a repeating unit which has a fluorescence peak in 500-720 nm.
In addition, in this specification, it is a repeating unit represented by General formula (1), Comprising: The polyimide which consists of a repeating unit has a fluorescence peak in 380-520 nm only in the repeating unit represented by General formula (1). When a polyimide is manufactured, it means having a fluorescent peak in the above range.

In the formula (1), R ¹ is a tetravalent aromatic group represented by the following general formula (3) or the following general formula (4), and R ² is a divalent organic group containing an alicyclic structure. is there.

In formula (3), R ⁴ is any one of a carbon-carbon single bond, an oxygen atom, a sulfonyl group, an aliphatic group optionally substituted with halogen, and an aromatic group via one or more divalent elements. Or a divalent substituent constituted by a combination thereof, or a single bond.
Examples of the aliphatic group include a long chain alkyl group such as a methylene group, an ethylene group, an isopropylidene group, and a hexamethylene group. These aliphatic groups may be substituted with halogens such as fluorine, chlorine, bromine and iodine. The aromatic group via one or more divalent elements is, for example, an aromatic group bonded via an oxygen atom (—O—) or an aromatic group bonded via a sulfonyl group (—SO ₂ —). This aromatic group may be substituted with a halogen such as fluorine, chlorine, bromine or iodine.

In the formula (4), R ⁴ and R ⁵ may be the same or different, and a carbon-carbon single bond, an oxygen atom, a sulfonyl group, an aliphatic group optionally substituted with a halogen, It is a divalent substituent or a single bond which is either an aromatic group via one or more divalent elements, or a combination thereof.
Examples of the aliphatic group include a long chain alkyl group such as a methylene group, an ethylene group, an isopropylidene group, and a hexamethylene group. These aliphatic groups may be substituted with halogens such as fluorine, chlorine, bromine and iodine. The aromatic group via one or more divalent elements means, for example, an aromatic group bonded via an oxygen atom or an aromatic group bonded via a sulfonyl group. The group may be substituted with a halogen such as fluorine, chlorine, bromine or iodine.

In General Formula (2), R ³ represents a tetravalent aromatic group represented by the following General Formula (5).

In formula (5), X and Y may be the same or different, an aliphatic group optionally substituted with halogen, an aromatic group via one or more divalent elements, a halogen of It is a divalent substituent that is either or a combination thereof.
Examples of the aliphatic group include a long chain alkyl group such as a methylene group, an ethylene group, an isopropylidene group, and a hexamethylene group. These aliphatic groups may be substituted with halogens such as chlorine, bromine and iodine. The aromatic group via one or more divalent elements means, for example, an aromatic group bonded through an oxygen atom, and the aromatic group is substituted with a halogen such as chlorine, bromine, or iodine. May be.

Examples of R ¹ in the general formula (1) include those having a structure capable of forming an acid dianhydride, for example, those represented by the following formulas (6) to (14).

In the general formulas (1) and (2), R ² is a divalent organic group including an alicyclic structure, and the organic group may include a halogen atom. For example, the following formula (15) and What is represented by (16) is mentioned.

In addition, R ² in the general formula (2) may be an organic group having a perfluoroalkyl group such as a trifluoromethyl group or a hexafluoroisopropylidene group. Examples of such a group include the following formula ( 17) and (18).

In the general formula (2), R ² is a divalent organic group including an alicyclic structure, and R ³ is a tetravalent aromatic group represented by the following general formula (5).

In the general formula (5), X and Y may be the same or different, an aliphatic group which may be substituted with a halogen, an aromatic group via one or more divalent elements, A divalent substituent which is any of halogen or a combination thereof is shown.
Examples of the tetravalent aromatic group represented by the general formula (5) include those represented by the following formula (19).

The fluorescent material of the present invention includes a polyimide copolymer having a repeating unit represented by the above general formula (1) and a repeating unit represented by the above general formula (2), wherein R ¹ in the general formula (1) is It is a tetravalent aromatic group, has low water absorption, and is suitable for use as a fluorescent optical device. Further, since the R ² of the general formulas (1) and (2) having an alicyclic structure, charge transfer interactions between polyimide intramolecular and are suppressed. Therefore, the fluorescent material of the present invention can exhibit high fluorescence intensity. The polyimide having the repeating unit represented by the general formula (1) is fluorescent emission from the ultraviolet long wavelength region to the visible short wavelength to medium wavelength region, that is, purple to blue to green fluorescent emission (fluorescence peak wavelength of 380 to 520 nm, preferably 380-500 nm, more preferably 400-450 nm). On the other hand, the polyimide having the repeating unit represented by the general formula (2) exhibits bright red fluorescence (fluorescence peak wavelength of 560 to 760 nm, preferably 600 to 720 nm, more preferably 650 to 700 nm).

The light emission mechanism of these copolymers is shown in FIGS. 1a and b. These copolymers exhibit fluorescence with high whiteness because the fluorescent light emission mechanism of the repeating unit represented by the general formula (1) and the repeating unit represented by the general formula (2) is independent. Not only remains, but because the former fluorescence spectrum is superimposed on the latter excitation spectrum (the spectrum of light absorption ability to cause fluorescence emission), the energy acquired by the former light irradiation is the latter. As a result, the fluorescence emission in the long wavelength region (red region) is also induced. This light emission mechanism is shown in FIG. In addition, the inventors of the present invention have a case where R ^{3 of the} repeating unit represented by the general formula (2) is 1,4-difluorobenzene, that is, a case where it is represented by the general formula (19) (polyimide raw material is 1,4 -Difluoropyromellitic acid), revealing the existence of a unique luminescence mechanism as shown in FIG. 1b.
That is, when the repeating unit represented by the general formula (1) as a constituent component is irradiated with ultraviolet light having a wavelength of 280 to 370 nm, the electrons present in the 1,4-difluoropyromellitic acid moiety are first excited to the excited state 1. As a direct emission relaxation from the excited state, fluorescence having a wavelength of 380 to 480 nm is shown. However, most of the energy is transferred to the repeating unit represented by the general formula (2) through an energy transfer mechanism between molecules in the excited state or within the molecule, and the wavelength is 480 to 600 nm as emission relaxation from the excited state 2. The fluorescence of is shown. This excited state 2 corresponds to a vertical excited state in the case where the repeating unit represented by the general formula (2) is irradiated with ultraviolet light or visible short wavelength light. (Locally Excited State). On the other hand, the repeating unit represented by the general formula (2) is capable of forming an excited state 3 (Charge Transferred Excited State) in which the charge is greatly transferred between the same molecule or other adjacent repeating units. The energy ranking of the excited state 3 is significantly lower than that of the first excited state and the second excited state. The energy transfer from the excited state 2 to the excited state 3 is subsequently induced through the intermolecular or intramolecular energy transfer mechanism, and the fluorescence emission from the excited state 3 is observed at a wavelength of 600 to 720 nm. As a result, continuous excitation of energy from the excited state 1 to the excited state 2 and then the excited state 3 occurs by exciting the electrons in the unoccupied orbital state only to the excited state 1, and fluorescence emission from each excited state. Are added together and observed, so that the fluorescence spectrum spreads over the entire visible range and exhibits high whiteness fluorescence. Therefore, the component ratio of the fluorescence of the repeating unit represented by the general formula (1) and the fluorescence of the repeating unit represented by the general formula (2) is the most important factor determining the fluorescence spectrum shape of the copolymer. In order to obtain fluorescence with high whiteness, the copolymerization ratio needs to be precisely controlled according to the combination of the structural formulas of the two components. In addition, the optimum excitation wavelength for emitting white fluorescence with high efficiency is substantially equal to the excitation wavelength of the repeating unit represented by the general formula (1) alone, so the excitation wavelength of the white fluorescent polyimide is controlled. For this purpose, the structure of the repeating unit represented by the general formula (1) needs to have a desired excitation wavelength.

The copolymerization ratio of the repeating unit represented by the general formula (1) and the repeating unit represented by the general formula (2) is the repeating unit represented by the general formula (1): the general formula (2). The represented repeating unit is preferably 75:25 to 99: 1 (molar ratio), more preferably 90:10 to 99: 1 (molar ratio). In order to make the copolymerization ratio within the above range, when synthesizing polyimide, an acid dianhydride for obtaining a repeating unit represented by the above general formula (1), a repeating unit represented by the above general formula (2) It can be achieved by adjusting the amount of acid dianhydride used to obtain.
The copolymerization ratio of the repeating unit represented by the general formula (1) and the repeating unit represented by the general formula (2) is a repeating unit represented by the general formula (1) used for producing polyimide. It can be calculated from the amount of acid dianhydride for obtaining the acid dianhydride for obtaining the repeating unit represented by the general formula (2).

  As a polyimide contained in the fluorescent material of the present invention, for example, any of the repeating units represented by the following formulas (20) to (31) and the repeating unit represented by any of the following formulas (32) to (34) And polyimide containing.

  The molecular weight of the polyimide contained in the fluorescent material of the present invention is not particularly limited as long as the fluorescence characteristics are exhibited, but the molecular weight of the precursor (polyamic acid or polyamic acid ester) is 0. It is preferably in the range of 05 to 5.0 (dl / g) (concentration 0.5 g / dl in an organic solvent at a temperature of 30 ° C.).

  Although there is no restriction | limiting in particular in the manufacturing method of the polyimide contained in the fluorescent material of this invention, For example, the polyamic acid obtained by polycondensing the mixture which consists of said 2 types of acid dianhydrides, and said diamine compound is used. It can be manufactured by heating and ring closure. There is no restriction | limiting in particular in the method of carrying out a heat ring closure, A conventionally well-known method is used.

Examples of the acid dianhydride include pyromellitic dianhydride, 1,4-bis (3,4-dicarboxyphenoxy) benzene dianhydride, 3,3 ′, 4,4′-oxybisphthalic acid Anhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 2,2-bis (3,4-dicarboxy) propane And dianhydrides and bis (3,4-dicarboxy) methane dianhydrides. Tetracarboxylic acids having the same basic skeleton as those, acid chlorides and esterified products thereof can also be used as raw materials for producing the polyimide copolymer contained in the fluorescent material of the present invention.
In order to obtain a repeating unit represented by the following general formula (1), the acid dianhydride used is represented by the following general formula (35) or (36), but is represented by the following general formula (2). In order to obtain a repeating unit, what is represented by the following general formula (37) is mentioned.

In the general formulas (35) and (36), R ⁴ and R ⁵ may contain a carbon-carbon single bond or a halogen atom other than fluorine (chlorine, bromine, iodine), and 2,2-bis (3,4-dicarboxytrifluorophenoxy) propane dianhydride, 1,4-bis (3,4-dicarboxytrifluorophenoxy) benzene dianhydride, 1,4-bis (3,4-dicarboxytri Fluorophenoxy) tetrachlorobenzene dianhydride, 2,2 ′, 5,5 ′, 6,6′-hexafluoro-3,3 ′, 4,4 ′,-biphenyltetracarboxylic dianhydride and the like. In the general formula (37), X and Y may be the same or different and may be substituted with halogen, such as difluoropyromellitic dianhydride, dichloropyromellitic dianhydride, etc. Can also be used.

  Examples of the diamine compound include 1,4-diaminocyclohexane, 4,4′-diaminodicyclohexylmethane, 2,2′-bis (trifluoromethyl) -4,4′-diaminobicyclohexane, 2,2′-bis. (4-aminocyclohexyl) -hexafluoropropane and the like and structural isomers thereof.

Below, an example of the manufacturing method of a film using the fluorescent material of this invention is shown.
First, in a polar organic solvent, a mixture of 1,4-bis (3,4-dicarboxyphenoxy) benzene dianhydride and difluoropyromellitic dianhydride in an arbitrary molar ratio is converted to 4,4′-diaminodicyclohexylmethane. Are polycondensed to obtain a polyamic acid solution. At this time, when a silyl esterified product such as N, O-bis (trimethylsilyl) acetamide or N, O-bis (trimethylsilyl) trifluoroacetamide is mixed, insolubilization (gelation) of the raw material aggregates and products hardly occurs. Become. Examples of the polar organic solvent used include N-methyl-4-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide and the like. The concentration of the raw material compound in the polymerization solution is preferably 5 to 40% by weight, more preferably 10 to 25% by weight. This reaction is shown in the following formula.

  The polyamic acid solution obtained as described above is spin-coated on a fused quartz plate, and heated in two stages, for example, at a temperature of about 70 ° C. and a temperature of about 300 ° C. in a nitrogen atmosphere, and imidized. This reaction is shown in the following formula. For example, the heating may be performed at 70 ° C. for 1 hour and at 300 ° C. for 1 hour 30 minutes. After imidation, a polyimide film is obtained by peeling from the quartz plate in air or water. When peeling from the quartz plate is difficult, a polyimide film is obtained by spin-coating a polyamic acid solution on the aluminum plate, thermal imidization, and then immersing the substrate together with 10% hydrochloric acid to dissolve the aluminum plate.

  As a method for synthesizing the polyamic acid, in addition to the method of synthesizing using a polar organic solvent as described above, the sublimation property of the acid dianhydride and the diamine compound as raw materials is used to form a polyamic acid on the substrate by vacuum deposition polymerization. The method of synthesizing is mentioned. As a method for synthesizing the polyimide film in this case, specifically, an acid dianhydride monomer and a diamine monomer are evaporated by heating respective vapor deposition sources in a vacuum chamber, and a polyamic acid is synthesized on the substrate. Furthermore, a polyimide thin film can be obtained by heating this in inert gas and carrying out dehydration ring closure. Further, if necessary, imidization may be performed by chemical treatment with a combination of a ring-closing catalyst such as pyridine / acetic anhydride and a dehydrating agent.

The fluorescent material of the present invention can be used as a material for organic light-emitting devices such as organic EL elements, organic lasers, and spatial light modulation elements. For example, using the fluorescent material film of the present invention as a light emitting layer / light receiving layer, an organic EL device is formed by forming a laminate of transparent substrate / transparent electrode / charge transport layer / light emitting layer / light receiving layer / electrode. Can do.
In addition, it can be used for optical waveguides and light sources for communication, optical fiber amplifiers, optical brighteners, paints, inks, fluorescent collectors, scintillators, plant growth films, and the like.

Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these examples.
Example 1
To an Erlenmeyer flask, 0.422 g (1.05 mmol) of 1,4-bis (3,4-dicarboxyphenoxy) benzene dianhydride (HQDEA), 0.0141 g of difluoropyromellitic dianhydride (P2FDA) (0. 0,535 mmol), and 4,32′-diaminodicyclohexylmethane (DCHM) 0.232 g (1.11 mmol), and N, N-dimethylacetamide (DMAc) so that the raw material concentration of the solution is 12.5 wt%. 4.69 g was added. The solution in the Erlenmeyer flask was stirred in a nitrogen atmosphere at room temperature for 24 hours to obtain a DMAc solution of polyamic acid. The obtained DMAc solution of polyamic acid was spin-coated on a quartz plate having a diameter of 75 mm, and heated in a nitrogen atmosphere at 70 ° C. for 1 hour, at 300 ° C. for 1 hour 30 minutes, and heated for imidization. It was. The layer formed by heating imidation was peeled from the quartz plate to obtain a polyimide thin film containing polyimide, which is a fluorescent material. The copolymer ratio of the repeating unit represented by the general formula (21) and the repeating unit represented by the general formula (32) in the polyimide contained in the obtained polyimide thin film is represented by the general formula (21). Repeating unit: The repeating unit represented by the general formula (32) is 95: 5 (molar ratio).

The infrared absorption spectrum of the obtained polyimide thin film was measured by attenuated total reflection (ATR) method, the absorption specific to carbonyl of the imide group to 1777cm ^-1 and 1719 cm ^-1 was observed, also observed in the polyamic acid Absorption peculiar to the amide bond at 1677 cm ⁻¹ and 1637 cm ⁻¹ disappeared, and it was confirmed that imidization proceeded completely. It was 3.2 micrometers when the film thickness of the obtained thin film was measured with the stylus type film thickness meter. When the obtained polyimide thin film was excited by irradiation with ultraviolet light having a wavelength of 320 nm and the fluorescence observation wavelength (fluorescence wavelength) was measured at 300 to 800 nm, strong fluorescence was observed at 350 to 700 nm. The results are shown in FIG. In FIG. 2, the vertical axis represents fluorescence intensity (logarithmic display), and the horizontal axis represents wavelength (nm). As shown in FIG. 2, the fluorescent material obtained in Example 1 had bright white fluorescence with the fluorescence wavelength extending over the entire visible range. Therefore, the fluorescence quantum yield of the obtained polyimide (white light emitting polyimide) was measured according to the method described in Y. Gen, A Trajkovska, et al. J. Am. Chem. Soc., 124, 8337 (2002). . That is, a film sample prepared by dissolving anthracene at a concentration of 1 × 10 ⁻² mol / l in a highly transparent and non-fluorescent polymethylmethacrylate resin was prepared, and the fluorescence intensity was measured and the anthracene fluorescence was measured. The quantum yield was calibrated as 0.28, and the fluorescence quantum yield of the white fluorescent material obtained above was estimated. The fluorescence quantum yield of the obtained polyimide was 0.044.
Moreover, when the polyimide thin film was immersed in water for 3 days and the water absorption was calculated | required by the increase in weight, it was 1.0%.

Example 2
Into an Erlenmeyer flask, 0.429 g (1.07 mmol) of 1,4-bis (3,4-dicarboxyphenoxy) benzene dianhydride (HQDEA), 0.00839 g of difluoropyromellitic dianhydride (P2FDA) (0. 0,330 mmol), and 4,4′-diaminodicyclohexylmethane (DCHM) 0.231 g (1.10 mmol), and N, N-dimethylacetamide (DMAc) so that the concentration of the raw material of the solution is 12.5 wt% 4.69 g was added. The solution in the Erlenmeyer flask was stirred in a nitrogen atmosphere at room temperature for 24 hours to obtain a DMAc solution of polyamic acid. The obtained DMAc solution of polyamic acid was spin-coated on a quartz plate having a diameter of 75 mm, and heated in a nitrogen atmosphere at 70 ° C. for 1 hour, at 300 ° C. for 1 hour 30 minutes, and heated for imidization. It was. The layer formed by heating imidation was peeled from the quartz plate to obtain a polyimide thin film containing polyimide, which is a fluorescent material. The copolymer ratio of the repeating unit represented by the general formula (21) and the repeating unit represented by the general formula (32) in the polyimide contained in the obtained polyimide thin film is represented by the general formula (21). Repeating unit: The repeating unit represented by the general formula (32) is 97: 3 (molar ratio).

The infrared absorption spectrum of the obtained polyimide thin film was measured by attenuated total reflection (ATR) method, the absorption specific to carbonyl of the imide group to 1777cm ^-1 and 1719 cm ^-1 was observed, also observed in the polyamic acid Absorption peculiar to the amide bond at 1677 cm ⁻¹ and 1637 cm ⁻¹ disappeared, and it was confirmed that imidization proceeded completely. It was 3.0 micrometers when the film thickness of the obtained thin film was measured with the stylus type film thickness meter. When the obtained polyimide thin film was excited by irradiation with ultraviolet light having a wavelength of 320 nm and the fluorescence observation wavelength (fluorescence wavelength) was measured at 300 to 800 nm, strong fluorescence was observed at a wavelength of 350 to 700 nm. The results are shown in FIG. In FIG. 2, the vertical axis represents fluorescence intensity (logarithmic display), and the horizontal axis represents wavelength (nm). As shown in FIG. 2, the fluorescent material obtained in Example 2 showed a bright white fluorescence with the fluorescence wavelength extending over the entire visible range. When the fluorescence quantum yield of this fluorescent material was estimated by the same method as in Example 1, it was 0.091.
Moreover, when the polyimide thin film was immersed in water for 3 days and the water absorption was determined by weight increase,
1.0%.

Example 3
Into an Erlenmeyer flask, 0.277 g (0.942 mmol) of 3,4,3 ′, 4′-biphenyltetracarboxylic dianhydride (s-BPDA), 0.00998 g of difluoropyromellitic dianhydride (P2FDA) (0 0,393 mmol), and 0.206 g (0.981 mmol) of 4,4′-diaminodicyclohexylmethane (DCHM) and N, N-dimethylacetamide (DMAc) so that the concentration of the raw materials in the solution is 7.0 wt%. ) 6.56 g was added. The solution in the Erlenmeyer flask was stirred in a nitrogen atmosphere at room temperature for 24 hours to obtain a DMAc solution of polyamic acid. The obtained DMAc solution of polyamic acid was spin-coated on a quartz plate having a diameter of 75 mm, and heated in a nitrogen atmosphere at 70 ° C. for 1 hour, at 300 ° C. for 1 hour 30 minutes, and heated for imidization. It was. The layer formed by heating imidization was peeled from the quartz plate to obtain a polyimide thin film containing a fluorescent material. The copolymer ratio of the repeating unit represented by the general formula (23) and the repeating unit represented by the general formula (32) in the polyimide contained in the obtained polyimide thin film is represented by the general formula (23). Repeating unit: The repeating unit represented by the general formula (32) is 96: 4 (molar ratio).

The infrared absorption spectrum of the obtained polyimide thin film was measured by attenuated total reflection (ATR) method, the absorption specific to carbonyl of the imide group to 1777cm ^-1 and 1719 cm ^-1 was observed, also observed in the polyamic acid Absorption peculiar to the amide bond at 1677 cm ⁻¹ and 1637 cm ⁻¹ disappeared, and it was confirmed that imidization proceeded completely. It was 2.0 micrometers when the film thickness of the obtained thin film was measured with the stylus type film thickness meter. When the obtained polyimide thin film was excited by irradiation with ultraviolet light having a wavelength of 364 nm and the fluorescence observation wavelength (fluorescence wavelength) was measured at 300 to 800 nm, strong fluorescence was observed at a wavelength of 350 to 700 nm. The results are shown in FIG. As shown in FIG. 2, the fluorescent material obtained in Example 3 showed bright white fluorescence with the fluorescence wavelength extending over the entire visible range. When the fluorescence quantum yield of this fluorescent material was estimated by the same method as in Example 1, it was 0.042.
Moreover, when the polyimide thin film was immersed in water for 3 days and the water absorption was calculated | required by the increase in weight, it was 0.9%.

Example 4
Into an Erlenmeyer flask, 0.776 g (2.50 mmol) of 3,3 ′, 4,4′-biphenyl ether tetracarboxylic dianhydride (ODPA), 0.0197 g of difluoropyromellitic dianhydride (P2FDA) (0. 0,766 mmol), and 4,43′-diaminodicyclohexylmethane (DCHM) 0.543 g (2.59 mmol), and N, N-dimethylacetamide (DMAc) so that the concentration of the raw material of the solution is 12.5 wt% 9.37 g was added. The solution in the Erlenmeyer flask was stirred in a nitrogen atmosphere at room temperature for 24 hours to obtain a DMAc solution of polyamic acid. The obtained DMAc solution of polyamic acid was spin-coated on a quartz plate having a diameter of 75 mm, and heated in a nitrogen atmosphere at 70 ° C. for 1 hour, at 300 ° C. for 1 hour 30 minutes, and heated for imidization. It was. The layer formed by heating imidization was peeled from the quartz plate to obtain a polyimide thin film containing a fluorescent material. The copolymer ratio of the repeating unit represented by the general formula (20) and the repeating unit represented by the general formula (32) in the polyimide contained in the obtained polyimide thin film is represented by the general formula (20). Repeating unit: The repeating unit represented by the general formula (32) is 97: 3 (molar ratio).

The infrared absorption spectrum of the obtained polyimide thin film was measured by attenuated total reflection (ATR) method, the absorption specific to carbonyl of the imide group to 1777cm ^-1 and 1719 cm ^-1 was observed, also observed in the polyamic acid Absorption peculiar to the amide bond at 1677 cm ⁻¹ and 1637 cm ⁻¹ disappeared, and it was confirmed that imidization proceeded completely. It was 2.5 micrometers when the film thickness of the obtained thin film was measured with the stylus type film thickness meter. When the obtained polyimide thin film was excited by irradiation with ultraviolet light having a wavelength of 347 nm, and its fluorescence observation wavelength (fluorescence wavelength) was measured at 300 to 800 nm, strong fluorescence was observed at a wavelength of 350 to 700 nm. The results are shown in FIG. As shown in FIG. 2, the fluorescent material obtained in Example 4 showed a bright white fluorescence with the fluorescence wavelength extending over the entire visible range. The fluorescence quantum yield of this fluorescent material was estimated by the same method as in Example 1 to be 0.019.
Moreover, when the polyimide thin film was immersed in water for 3 days and the water absorption was calculated | required by the increase in weight, it was 0.9%.

  As described above, when the fluorescent materials obtained in Examples 1 to 4 were excited by irradiation with ultraviolet light having a wavelength of 300 to 365 nm, the emission wavelength was in the visible range of 350 to 700 nm as shown in FIG. It was widely available, and its emission intensity was so high that it could be easily confirmed visually. From this, it was confirmed that the fluorescent material containing polyimide obtained in Examples 1 to 4 is suitable as a white light emitting device material. Furthermore, these polyimide-containing fluorescent materials have a thermal decomposition starting temperature of 415 ° C. or higher, and are much higher than conventional polymer fluorescent materials, so they have excellent heat resistance and moisture absorption rate. Therefore, it was confirmed that it is suitable as a photoelectric device material.

Comparative Example 1
Into an Erlenmeyer flask, 1.55-g (5.0 mmol) of 1,4-bis (3,4-dicarboxyphenoxy) benzene dianhydride (HQDEA) and 1.05 g of 4,4′-diaminodicyclohexylmethane (DCHM) (5 0.0 mmol), and 14.7 g of N, N-dimethylacetamide (DMAc) was added so that the concentration of the raw material in the solution was 15% by weight. The solution in the Erlenmeyer flask was stirred in a nitrogen atmosphere at room temperature for 24 hours to obtain a DMAc solution of polyamic acid. The obtained polyamic acid DMAc solution was spin-coated on a quartz plate having a diameter of 75 mm, and stepwise in a nitrogen atmosphere at 70 ° C. for 2 hours, 160 ° C. for 1 hour, 250 ° C. for 30 minutes, and 300 ° C. for 2 hours. The solution was heated to imidation by heating. A layer formed by heating imidation was peeled off from the quartz plate to obtain a polyimide thin film containing a fluorescent material containing polyimide as a fluorescent material.

The infrared absorption spectrum of the obtained polyimide thin film was measured by attenuated total reflection (ATR) method, the absorption specific to carbonyl of the imide group to 1777cm ^-1 and 1719 cm ^-1 was observed, also observed in the polyamic acid Absorption peculiar to the amide bond at 1677 cm ⁻¹ and 1637 cm ⁻¹ disappeared, and it was confirmed that imidization proceeded completely. When the fluorescence emission spectrum of this polyimide thin film was measured at an excitation wavelength of 345 nm, fluorescence was observed at a central wavelength of 415 nm, and it was blue-violet. The results are shown in FIG. As shown in FIG. 3, in the fluorescent material obtained in Comparative Example 1, the fluorescence wavelength did not spread over the entire visible range. When the absorption edge of this polyimide thin film was measured, it was an ultraviolet region with a wavelength of 354 nm.

Comparative Example 2
Instead of HQDEA in Comparative Example 1, 1.27 g (5.0 mmol) of difluoropyromellitic dianhydride (P2FDA) was used to prepare a DMAc solution (10 wt%) of polyamic acid in the same manner as in Example 1. The polyimide thin film was prepared. The thickness of the obtained thin film was 14.0 μm, and the 5% weight loss temperature was 394 ° C. When the fluorescence emission spectrum of the polyimide thin film was measured at an excitation wavelength of 543 nm, fluorescence was observed at center wavelengths of 590 nm and 706 nm, and the color was reddish orange. The results are shown in FIG. As shown in FIG. 3, in the fluorescent material obtained in Comparative Example 1, the fluorescence wavelength did not spread over the entire visible range.

Comparative Example 3
The same method as in Example 1 except that 1.47 g (5.0 mmol) of 3,4,3 ′, 4′-biphenyltetracarboxylic dianhydride (s-BPDA) was used instead of HQDEA in Comparative Example 1. A DMAc solution (10% by weight) of polyamic acid was prepared to prepare a polyimide thin film. When the fluorescence emission spectrum of this polyimide thin film was measured at an excitation wavelength of 365 nm, fluorescence was observed at a central wavelength of 398 nm, and it was blue-violet. The results are shown in FIG. As shown in FIG. 3, in the fluorescent material obtained in Comparative Example 3, the fluorescence wavelength did not spread over the entire visible range.

Comparative Example 4
In place of HQDEA in Comparative Example 1, 1.55 g (5.0 mmol) of 3,3 ′, 4,4′-biphenyl ether tetracarboxylic dianhydride (ODPA) was used in the same manner as in Example 1. A polyamic acid DMAc solution (10 wt%) was prepared to prepare a polyimide thin film. When the fluorescence emission spectrum of this polyimide thin film was measured at an excitation wavelength of 347 nm, fluorescence was observed at a central wavelength of 399 nm, and it was blue-violet. The results are shown in FIG. As shown in FIG. 3, in the fluorescent material obtained in Comparative Example 4, the fluorescence wavelength did not spread over the entire visible range.

It is the figure which showed the fluorescence light emission mechanism. It is a graph which shows the result of having measured the fluorescence intensity of the fluorescent material. It is a graph which shows the result of having measured the fluorescence intensity of the fluorescent material.

Claims (2)

A repeating unit represented by the following general formula (1), wherein the polyimide composed of the repeating unit has a fluorescence peak at 380 to 520 nm,
The fluorescent material containing the polyimide which is a repeating unit represented by following General formula (2), Comprising: The polyimide which consists of this repeating unit has a repeating unit which has a fluorescence peak in 560-760 nm.

(In the formula, R ¹ represents an aromatic group represented by the following general formula (6), (7), (8), (9), (10) or (14)), and R ² represents the following general formula. (15) Indicates an alicyclic alkyl group represented by (16), (17) or (18) .

Wherein R ² represents an alicyclic alkyl group represented by the following general formula (15), (16), (17) or (18), and R ³ is represented by the following general formula (5). A tetravalent aromatic group.)

(In the formula, X and Y may be the same or different and each represents a halogen .) The fluorescent material according to claim 1, wherein R ³ in the general formula (2) is represented by the following general formula (19).

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