Near-infrared light absorbent, and composition and optical filter containing near-infrared light absorbent

Abstract

The invention discloses a near-infrared light absorbent, and a composition and an optical filter containing the near-infrared light absorbent. The near-infrared light absorbent has a structure as shown in a formula (I): # imgabs0 # (I), wherein: R1 is independently selected from H, C1-C8 alkyl; r2 is independently selected from H and C1-C6 alkyl; r3 is independently selected from H and C1-C4 alkyl; r4 is independently selected from the following groups: # imgabs 1 #, wherein R5 is selected from C1-C12 straight chain or branched chain alkyl, phenyl and C1-C4 alkyl substituted phenyl; n is 1, 2, 3 or 4. The large infrared light maximum absorption wavelength lambdamax and IR T50% are achieved, and the imaging color of the visible light filter can be improved.

Description

Technical Field

[0001] The present invention particularly relates to a near-infrared light absorber and a composition and a filter containing the same. Background Art

[0002] Visible light filters are optical devices used to select visible light. They absorb infrared (including near-infrared) and ultraviolet light, blocking them from passing through, thereby allowing only visible light to pass. This absorption is typically achieved by applying a coating that absorbs both infrared and ultraviolet light to the filter's substrate (plastic or glass).

[0003] Infrared light absorbers, such as near-infrared light absorbers, need to maximize the absorption of near-infrared light while ensuring sufficient transmission of visible light. However, the wavelength of near-infrared light is not much different from that of visible light, making it difficult to achieve the aforementioned requirements.

[0004] Patent WO2014088063A1 discloses compound A1 with the following structural formula The compound was used as a near-infrared absorbing pigment in near-infrared cutoff filters. However, the maximum absorption wavelength λmax of this compound is 704.7nm (tested in toluene), which still cannot meet the transmittance requirements of the filter in the visible light region.

[0005] Under the premise of ensuring sufficient transmission of visible light, it is very necessary to increase the maximum absorption wavelength λmax of the near-infrared absorber and the wavelength corresponding to 50% infrared spectrum transmittance (IR T50%). In this way, the color deviation of the filter can be improved, making the imaging color of the filter closer to the real color. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to address the shortcomings and deficiencies of the existing technology and provide a near-infrared light absorber, which has a larger maximum infrared light absorption wavelength λmax and a wavelength IRT50% corresponding to 50% infrared spectrum transmittance. When applied to a visible light filter, it can improve its imaging color.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions: A near-infrared light absorber having a structure represented by formula (I), ; in: R1 is independently selected from H, C1-C8 alkyl; R2 is independently selected from H, C1-C6 alkyl; R3 is independently selected from H, C1-C4 alkyl; R4 is independently selected from the following groups: , wherein R5 is selected from C1-C12 linear or branched alkyl, phenyl, C1-C4 alkyl-substituted phenyl; n is 1, 2, 3, or 4.

[0008] In the prior art, near-infrared light absorbers can generally be onium salt absorbers, and the prior art has reported compound A1 While it can be used as a near-infrared light absorber, the compound's absorption spectrum has a maximum absorption wavelength, λmax, at 704.7 nm (tested in toluene). The wavelength corresponding to 50% infrared transmittance (IR T50%) is relatively low, failing to meet the stringent requirements of visible light filters. The inventors of this application, through extensive research, discovered that introducing a new ring structure into the five-membered nitrogen-containing heterocyclic ring of Compound A1 can enhance the electron-donating ability of this ring, thereby increasing the conjugation of the entire compound molecule. This can increase the maximum absorption wavelength of the compound's absorption spectrum (i.e., red-shift) without affecting the compound's transmittance in the visible light region. When used as a near-infrared light absorber, its near-infrared absorption performance is significantly enhanced, which is highly advantageous in visible light filters, improving imaging color.

[0009] In some embodiments, R1 is independently C1-C6 alkyl.

[0010] In some embodiments, R1 is butyl.

[0011] In some embodiments, R2 is independently selected from H, C1-C4 alkyl.

[0012] In some embodiments, R2 is methyl.

[0013] In some embodiments, R3 is H.

[0014] In some embodiments, R4 is independently , and R5 is independently selected from C3-C8 linear or branched alkyl, phenyl, methyl-substituted phenyl; or, R4 is independently , and R5 is independently selected from phenyl, methyl substituted phenyl; or, R4 is independently , and R5 is independently selected from C6-C10 straight chain alkyl; or, R4 is independently , and R5 is independently selected from C4-C8 linear or branched alkyl groups.

[0015] In some embodiments, n is 1 or 2.

[0016] In some embodiments, the two R1s have the same structure, the two R2s have the same structure, the two R3s have the same structure, and the two R4s have the same structure, that is, the near-infrared light absorber of formula (I) has a symmetrical structure.

[0017] In some embodiments, the near-infrared light absorber is selected from the compounds of the following structures:

[0018] .

[0019] The present invention also provides a near-infrared light absorbing composition, which comprises the aforementioned near-infrared light absorber. The aforementioned near-infrared light absorber plays a role in absorbing near-infrared light in the composition and is the main active component of the composition's absorption performance.

[0020] The present invention does not limit other components in the near-infrared light-absorbing composition. Any commonly used components in near-infrared light-absorbing compositions in the art may be added to the composition, as long as they do not substantially affect the composition's near-infrared light absorption properties. For example, a matrix component such as a resin is typically used in the composition, and other commonly used components such as additives may also be added.

[0021] In some embodiments, the near-infrared light absorbing composition further comprises a resin selected from acrylic resins, epoxy resins, mercaptoethanol resins, polycarbonate resins, polyether resins, polyarylate resins, polysulfone resins, polyethersulfone resins, polyparaphenylene resins, polyarylether phosphine oxide resins, polyimide resins, polyamideimide resins, polyolefin resins, cycloolefin resins, and polyester resins.

[0022] Furthermore, the near-infrared light absorbing composition contains 0.1%-2% by mass of the aforementioned near-infrared light absorber.

[0023] The present invention also provides use of the aforementioned near-infrared light absorber or near-infrared light absorbing composition in a visible light filter.

[0024] Furthermore, the aforementioned near-infrared light absorber or near-infrared light absorbing composition is used in a near-infrared absorbing layer in a visible light filter.

[0025] The present invention also provides a visible light filter, comprising a substrate and a near-infrared light absorbing layer, wherein the near-infrared light absorbing layer contains the aforementioned near-infrared light absorber or near-infrared light absorbing composition.

[0026] Furthermore, the visible light filter includes a first multilayer film structure disposed on the back surface of the substrate. The first multilayer film structure comprises multiple films with different refractive indices. This first multilayer film structure typically comprises multiple films with high and low refractive indices stacked alternately. This multilayer film structure can absorb and block infrared light, thereby also shielding the back surface of the substrate from infrared light.

[0027] In some embodiments, the material of each layer in the first multilayer film structure is selected from a combination of one or more of TiO2, SiO2, Y2O3, MgF2, Al2O3, Nb2O5, AlF3, Bi2O3, Gd2O3, LaF3, PbTe, Sb2O3, Si3N4, Ta2O5, ZnS, ZnSe, ZrO2 and Na3AlF6.

[0028] Furthermore, the visible light filter further includes a second multi-layer film structure provided on the ultraviolet light absorbing layer, and the second multi-layer film structure is an anti-reflection layer.

[0029] In some embodiments, the material of each layer in the second multilayer film structure is selected from one or more combinations of TiO2, SiO2, Y2O3, MgF2, Al2O3, Nb2O5, AlF3, Bi2O3, Gd2O3, LaF3, PbTe, Sb2O3, Si3N4, Ta2O5, ZnS, ZnSe, ZrO2 and Na3AlF6.

[0030] Due to the implementation of the above technical solution, the present invention has the following advantages compared with the prior art: By introducing a new ring structure into the five-membered nitrogen-containing heterocycle of an onium salt near-infrared light absorber known in the art, the present invention enhances the electron-donating ability of the ring, thereby increasing the conjugation of the entire compound molecule. This increases the maximum absorption wavelength of the compound's absorption spectrum (i.e., red-shifts it) without affecting the compound's transmittance in the visible light region. When used as a near-infrared light absorber, its near-infrared light absorption performance is significantly improved, which is particularly beneficial when used in visible light filters, improving the image quality.

[0031] Compared with the compounds in the prior art, the near-infrared light absorber of the present invention has an absorption spectrum with a maximum absorption wavelength increased by 2-3 nm, has a significant red shift phenomenon, and has no significant change in the transmittance performance in the visible light region. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is the NMR spectrum of the target compound B1 in Example 1.

[0033] Figure 2 This is the NMR spectrum of the target compound B2 in Example 2.

[0034] Figure 3 This is the NMR spectrum of the target compound B3 in Example 3.

[0035] Figure 4 This is the NMR spectrum of the target compound B4 in Example 4.

[0036] Figure 5 This is the NMR spectrum of the target compound B5 in Example 5.

[0037] Figure 6 This is the NMR spectrum of the target compound B6 in Example 6.

[0038] Figure 7 This is the NMR spectrum of the target compound B7 in Example 7.

[0039] Figure 8 This is the NMR spectrum of the target compound B8 in Example 8.

[0040] Figure 9 This is the NMR spectrum of the target compound B9 in Example 9.

[0041] Figure 10 Comparison chart of absorption spectra of target compounds B1, B9 and comparative compound A1.

[0042] Figure 11 This is a comparison chart of the transmittance curves of target compound B1 and comparative compound A1 on white glass. DETAILED DESCRIPTION definition

[0043] In the compounds described herein, when any variable (e.g., R1, R2, etc.) occurs more than once in any component, the definition of each occurrence is independent of the definition of every other occurrence. Similarly, combinations of substituents and variables are permitted so long as such combinations result in a stable compound. The definition of any substituent or variable at a particular position in a molecule is independent of the definition of any other position in the molecule. It will be readily appreciated that one of ordinary skill in the art can select substituents or substituted patterns in the compounds of the present invention by means of existing techniques and the methods described herein to provide chemically stable and readily synthesized compounds.

[0044] As used herein, "alkyl" is intended to include both branched and straight-chain saturated aliphatic hydrocarbon groups having a specified number of carbon atoms. For example, the definition of "C1-6 alkyl" includes groups having 1, 2, 3, 4, 5, or 6 carbon atoms in a straight or branched chain.

[0045] The present invention is further described below with reference to examples, but the examples are not intended to limit the scope of protection of the present invention.

[0046] The technical features of the embodiments described below can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the following embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0047] The following examples merely illustrate several embodiments of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims. Example 1:

[0048] The target compound B1 was synthesized using the following reaction route:

[0049]

[0050] The specific synthesis steps are as follows: 1) In a 250 mL reaction flask, 25.0 g of methylcyclohexanone, 24.0 g of phenylhydrazine, and 150 mL of acetic acid were added. After reflux for 24 hours, the reaction system was extracted with ethyl acetate. The organic phase was separated and concentrated under reduced pressure to obtain liquid compound 1 in a yield of 99%.

[0051] 2) In a 250 mL reaction flask, 20.0 g of compound 1, 80 mL of ethyl acetate, and 29.6 g of bromobutane were added. The mixture was reacted at room temperature for 24 hours and then filtered to obtain solid compound 2 in a yield of 96%.

[0052] 3) To a 500 mL reaction flask, 25.0 g of compound 2 and 125 mL of methanol were added, and the temperature was cooled to 5°C. 3.9 g of sodium borohydride was slowly added to the reaction flask, and the mixture was reacted at 0-5°C for 2 hours. Saturated aqueous ammonium chloride solution was then added to terminate the reaction. The reaction system was extracted with ethyl acetate, and the organic phase was separated and concentrated under reduced pressure to obtain liquid compound 3 in a 95% yield.

[0053] 4) To a 250 mL reaction flask, add 72 g of concentrated sulfuric acid and 24.0 g of compound 3. The temperature was cooled to 5°C, and 6.5 g of concentrated nitric acid was slowly added dropwise. The reaction was carried out at 0-5°C for 2 h. 120 mL of water was added to terminate the reaction. The mixture was extracted with ethyl acetate and concentrated under reduced pressure to obtain liquid compound 4 in a 98% yield.

[0054] 5) In a 200 mL high-pressure reactor, 14.0 g of compound 4, 150 mL of toluene, and 0.7 g of Pd / C catalyst were added, and 5 kg of hydrogen was introduced for pressurization. The reaction was then carried out at 50°C for 24 hours. After completion of the reaction, the active Pd / C catalyst was removed by filtration through diatomaceous earth to obtain a liquid, which was then concentrated under reduced pressure to obtain liquid compound 5 with a yield of 90%.

[0055] 6) In a 100 mL reaction flask, 50 mL of dichloromethane and 11.3 g of compound 5 were added. The temperature was lowered to 5°C, and 4.6 g of isobutyryl chloride was slowly added dropwise to the reaction flask. The reaction was incubated at 0-5°C for 2 hours. 50 mL of water was then added to terminate the reaction. The organic layer was extracted and collected and concentrated under reduced pressure to obtain liquid compound 6 in a 100% yield.

[0056] 7) In a 250 mL reaction flask, add 100 mL of toluene, 14.3 g of compound 6, and 2.0 g of compound The mixture was mixed with 10.0 g of butanol, heated to 125 ° C, and dehydrated using a water separator for 24 hours. The mixture was cooled to room temperature and filtered to obtain solid compound II with a yield of 65%.

[0057] The NMR spectrum of target compound B1 is as follows Figure 1 shown. Example 2-8:

[0058] The same reaction route as in Example 1 was used, and the isobutyryl chloride in step 6) was replaced with R4-CO-Cl (R4-acyl chloride) of other structures to obtain compounds B2-B8 with structures similar to compound B1. The structures of R4 and compounds B2-B8 are shown below.

[0059] Example 2: R4 is , compound B2 is ; Example 3: R4 is , compound B3 is ; Example 4: R4 is , compound B4 is ; Example 5: R4 is , compound B5 is ; Example 6: R4 is , compound B6 is ; Example 7: R4 is , compound B7 is ; Example 8: R4 is , compound B8 is .

[0060] The NMR spectra of compounds B2-B8 are as follows: Figure 2-8 shown. Example 9:

[0061] The same reaction route as in Example 1 was used, except that the starting material was replaced by 2-methylcycloheptanone. Finally, the target compound B9 was obtained, whose structural formula is Its NMR spectrum is as follows Figure 9 shown. Comparative Example 1:

[0062] Comparative compound A1 is provided:

[0063] The specific synthetic route and synthetic steps are basically the same as those in Example 1, except that compound 1 is replaced by and used it directly as the starting material. Comparative Examples 2-8:

[0064] The same reaction route as in Comparative Example 1 was adopted, and the isobutyryl chloride in step 6) was replaced with R4-CO-Cl (R4-acyl chloride) of other structures to obtain compounds A2-A8 with structures similar to comparative compound A1. The structures of R4 and compounds A2-A8 are shown below.

[0065] Comparative Example 2: R4 is , compound A2 is ;

[0066] Comparative Example 3: R4 is , compound A3 is ; Comparative Example 4: R4 is , compound A4 is ; Comparative Example 5: R4 is , compound A5 is ; Comparative Example 6: R4 is , compound A6 is ; Comparative Example 7: R4 is , compound A7 is ; Comparative Example 8: R4 is , compound A8 is .

[0067] The compound B1 of Example 1, the compound B9 of Example 9 and the compound A1 of Comparative Example 1 were dissolved in toluene at a mass concentration of 3 ppm. The absorption spectra of the three were tested, and the results were as follows: Figure 10 As shown, the orange line represents compound B1, the green line represents compound B9, and the blue line represents compound A1. It can be seen that compound B1 produces a red shift relative to compound A1, and compound B9 produces an even greater red shift relative to A1. The maximum absorption wavelength λmax of the absorption spectra of the compounds in other examples and comparative examples was tested using the same method. The results are shown in Table 1 below.

[0068]

[0069] As can be seen from Table 1 above, the maximum absorption wavelength λmax of the absorption spectrum of the target compounds B1-B8 is red-shifted by about 2-3 nm relative to the comparative compounds A1-A8, respectively. This indicates that the further introduction of a ring structure into the molecular structure of the near-infrared pigment in this application can significantly increase the maximum absorption wavelength λmax of its absorption spectrum, which is very beneficial for its application in visible light filters.

[0070] Compound B1 from Example 1 and Compound A1 from Comparative Example 1 were mixed with a toluene solution of an acrylic resin (the mass percentage concentration of the acrylic resin was 10%) to obtain a coating solution. The mass percentage concentrations of Compounds B1 and A1 in the coating solution were both 0.45%. The coating solution was applied to white glass to a coating thickness of 1 μm. The transmittance of the entire sample in the visible and infrared regions was tested. The results were as follows: Figure 11 As shown, the blue line represents compound B1 (with an IR T50% of 679.91 nm and a minimum transmittance wavelength of 712 nm), while the yellow line represents compound A1 (with an IR T50% of 674.89 nm and a minimum transmittance wavelength of 708 nm). This shows that compound B1 exhibits a significant red shift relative to compound A1. However, in the visible light band, there is no significant difference in transmittance between the two compounds. This indicates that the compounds of this application can increase the near-infrared maximum absorption wavelength without compromising visible light transmittance.

[0071] The above embodiments are only intended to help understand the method and core concept of the present invention. It should be noted that, without departing from the principles of the present invention, a number of improvements and modifications may be made to the present invention by those skilled in the art, and such improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A near-infrared light absorber having a structure represented by formula (I), （I）； in: R1 is independently selected from H, C1-C8 alkyl; R2 is independently selected from H, C1-C6 alkyl; R3 is independently selected from H, C1-C4 alkyl; R4 is independently selected from the following groups: , wherein R5 is selected from C1-C12 linear or branched alkyl, phenyl, C1-C4 alkyl-substituted phenyl; n is 1, 2, 3, or 4.

2. The near-infrared light absorber according to claim 1, characterized in that: R1 is independently C1-C6 alkyl.

3. The near-infrared light absorber according to claim 1, wherein: R1 is butyl.

4. The near-infrared light absorber according to claim 1, wherein: R2 is independently selected from H, C1-C4 alkyl.

5. The near-infrared light absorber according to claim 1, wherein: R2 is methyl.

6. The near-infrared light absorber according to claim 1, wherein: R3 is H.

7. The near-infrared light absorber according to claim 1, wherein: R4 is independently , and R5 is independently selected from C3-C8 linear or branched alkyl, phenyl, methyl-substituted phenyl; or, R4 is independently , and R5 is independently selected from phenyl, methyl substituted phenyl; or, R4 is independently , and R5 is independently selected from C6-C10 straight chain alkyl; or, R4 is independently , and R5 is independently selected from C4-C8 linear or branched alkyl groups.

8. The near-infrared light absorber according to claim 1, wherein: n is 1 or 2.

9. The near-infrared light absorber according to claim 1, wherein: The two R1s have the same structure, the two R2s have the same structure, the two R3s have the same structure, and the two R4s have the same structure.

10. The near-infrared light absorber according to claim 1, characterized in that: The near-infrared light absorber is selected from the compounds with the following structures: ； ； 。 11. A near-infrared light absorbing composition, characterized in that: The method comprises the near-infrared light absorber according to any one of claims 1 to 10.

12. The near-infrared light absorbing composition according to claim 11, wherein: The near-infrared light absorbing composition further comprises a resin selected from acrylic resin, epoxy resin, mercaptoethanol resin, polycarbonate resin, polyether resin, polyarylate resin, polysulfone resin, polyethersulfone resin, polyparaphenylene resin, polyaryletherphosphine oxide resin, polyimide resin, polyamideimide resin, polyolefin resin, cycloolefin resin and polyester resin.

13. A visible light filter comprising a substrate and a near-infrared light absorbing layer, characterized in that: The near-infrared light absorbing layer contains the near-infrared light absorbing agent according to any one of claims 1 to 10.

14. A visible light filter comprising a substrate and a near-infrared light absorbing layer, characterized in that: The near-infrared light absorbing layer contains the near-infrared light absorbing composition according to claim 11 or 12.

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