JP2014534290A - SALT FOR COLOR FILTER APPLICATION, PROCESS FOR PRODUCING THE SAME, AND COLORANT CONTAINING THE SAME - Google Patents

Abstract

Disclosed are salts comprising at least one cationic cyanine compound as a cation and at least one anionic xanthene compound as an anion, as well as their use in color filters, for example for displays, and a method for their production. . The salts of the present invention provide improved properties, especially from the standpoint of thermal stability and / or brightness.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application claims priority to European Patent Application No. 11184165.6 filed Oct. 6, 2012, the entire contents of which are incorporated by reference for all purposes. Incorporated herein by reference.

  The present invention is generally directed to suitable salts for color filter applications, especially cyanine-xanthene salts, and methods for their production. More specifically, the present invention is directed to the manufacture of a salt comprising at least one cationic cyanine compound and at least one anionic xanthene compound that exhibits better properties for a color filter. Furthermore, the invention also relates to a display device, in particular a liquid crystal display incorporating the aforementioned salt.

  Color filters, particularly those used in liquid crystal display (LCD) devices and the like, are usually manufactured by first forming a pattern from a photoresist and then dyeing this pattern. However, this method is usually disadvantageous in that the dyeing process is complex and difficult to control. Accordingly, a method for producing a color filter by patterning a photoresist containing a pigment such as a pigment or dye as a colorant has been proposed. However, those methods are not suitable because the pigments / dyes used in them contain particles of relatively large size, for example about 1 μm size, or the resulting colored pattern is less stable. It is sometimes not suitable for the manufacture of color filters that require resolution.

  In addition to the above, these methods involve another important issue. That is, a normal dye exists as a foreign substance different from an alkali developable resist. Since the preferable thickness of the resist film is 1 μm or less in the case of manufacturing a color filter, a large amount of dye must be added to the resist composition containing a resin and an organic solvent. However, real dyes are not soluble in aqueous (alkali) solutions or organic solvents, and it is therefore difficult to produce fine color patterns from such dyes with the desired spectrum and small film thickness. Another drawback from such insolubility is that the pigment particles sometimes clump up and the performance of color filters made from the composition, such as brightness and contrast ratio, deteriorates.

  Recently, the use of soluble dyes such as cyanine dyes, xanthene dyes and azo dyes has been proposed to improve the solubility of colorants for color filters. U.S. Patent Application Publication No. 20080237553A1 discloses a colored photosensitive resin composition comprising an alkaline solution resin, a photosensitive compound, a curing agent, a solvent and a cyanine colorant, wherein the cyanine molecule is violet. Used as a colorant.

  U.S. Patent Application Publication No. 2004074018A1 is disclosed in C.I. I. An azo compound such as Reactive Red 23; I. Disclosed are dye mixtures consisting essentially of xanthene compounds such as Acid Red 52, as well as their use in inkjet printing, yielding storage stable, waterproof ink formulations.

  However, the above colorants and / or dyes have problems in that they still exhibit poor performance when used in color filters, especially in terms of contrast ratio and brightness. In addition, some dyes, particularly cyanine-based dyes, are not sufficiently stable and thus do not meet the requirements for device manufacturing, which often requires processing at high temperatures. Accordingly, there is still a strong desire in the art to develop a method that effectively improves color filter performance along with thermal stability by modifying such soluble dyes without the above drawbacks. .

  One object of the present invention is to develop a composition for a color filter that exhibits good performance, such as contrast ratio and brightness, when used as a color filter pigment for a liquid crystal display (LCD). is there.

  The inventors of the present invention have attempted to solve these problems and have discovered that the performance of color filter pigments can be improved when cyanine-xanthene salts are used. In addition, the inventors have also shown that when this salt is formed using an anionic xanthene compound and a cationic cyanine compound, it exhibits improved thermal stability and the color filter obtained from this salt is It has been found that better performance can be shown in terms of contrast ratio and brightness.

  The present invention therefore relates to a salt comprising as a cation at least one cationic cyanine compound and as an anion at least one anionic xanthene compound.

  Hereinafter, the present invention will be described in detail.

  The term “dye” is defined herein as a colorant that is soluble in water or other solvent. In particular, the dye has an affinity for the substrate to which it is applied. The term “pigment” is defined herein as a colorant that changes the color of reflected or transmitted light as a result of wavelength selective absorption and is insoluble in water and other solvents. In contrast to dyes, pigments are generally insoluble and have an affinity for the substrate, even though both dyes and pigments appear colored because they preferentially absorb light wavelengths. No sex at all. The term “salt” is defined herein as a solid or solution material formed from an anion and a cation.

In a first specific embodiment of the present invention, the anionic xanthene compound has the following formula (I)
[Where:
Each of R1, R2, R3 and R4 is the same or different and is independently hydrogen and alkyl, cycloalkyl having 1 to 4, preferably 1 to 2, more preferably 2 carbon atoms; And selected from the group consisting of aralkyl;
-M is 2-5]
It is represented by

  In this first specific embodiment, R1, R2, R3 and R4 may each be the same or different, preferably the same. R1, R2, R3 and R4 are advantageously independently alkyl having 1 to 4 carbon atoms, preferably methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl and t- It is selected from the group consisting of butyl, more preferably ethyl.

  In this first specific embodiment, m is typically 2-5, especially 2-4, more especially 2 or 3, such as 2.

In this first specific embodiment, when at least two SO ₃ ^— groups are present, at least one SO ₃ ^— group is ortho, meta or para, advantageously ortho or para, preferably At least in both ortho and para.

In an especially preferred embodiment, the anionic xanthene compound has the following formula (I-1)
It is represented by

  In the present invention, a xanthene compound represented by the formula (I), more specifically, the formula (I-1) can be produced by any method known in the art. For example, a xanthene compound of formula (I-1) can be prepared by addition of aminophenol and formyl-sulfonic acid sodium salt to p-toluenesulfonic acid, filtration of the mixture, washing and evaporation of the resulting filtrate. .

In a second specific embodiment of the present invention, the cationic cyanine compound has the following formula (II)
[Where:
-A and B are each the same or different, preferably the same, and independently an aromatic ring, heteroaromatic ring having 3 to 20 carbon atoms, preferably 6 to 16 carbon atoms, And a polyaromatic ring, especially selected from the group consisting of benzene or naphthalene, said group optionally substituted with fluorinated or non-fluorinated alkyls;
Each of R5 and R6 is the same or different, especially the same, and is independently optionally substituted with another atom, preferably halogen, more preferably fluorine, 1-30 Selected from the group consisting of alkyl, alkoxy and hydroxyalkyl having 1 carbon atom, preferably 2-20 carbon atoms, most preferably 4-15 carbon atoms;
X ₁ , X ₂ , X ₃ and X ₄ may be any kind of substituents, preferably each the same or different, in particular the same, and independently hydrogen or halogen, preferably May be selected from the group consisting of alkyl optionally substituted with fluorine;
Y ₁ , Y ₂ and Y ₃ are each the same or different and are independently selected from the group consisting of hydrogen, halogen, cyano, nitro, alkyl, and aryl groups, taken together as 5 or 6 May form a member ring;
-N is 1-5, preferably 1-3]
Is typically represented.

In some further specific embodiments, at least one of Y ₁ , Y ₂ and Y ₃ of formula (II) is cyano or halogen, preferably cyano or chlorine. In a preferred embodiment, at least one of X ₁ -X ₄ , R 5 and R 6 is alkyl substituted with at least one fluorine atom.

In a more specific embodiment, the cationic cyanine compound has the formula (II-1) to (II-6):
It is represented by any one of.

  In a more preferred embodiment, the cationic cyanine compound is represented by the above formula (II-6).

  In the present invention, the cyanine compound represented by the formula (II), more specifically, the formulas (II-1) to (II-6) is typically produced by at least three steps. it can. In the first step, an indolenine compound such as 2,3,3-trimethylindolenine is produced. In the second step, starting from an indolenine compound, an N-substituted indolium halide such as N-butyl 2,3,3-trimethylindolium iodide is synthesized. The N-substituted indolium halide is then subjected to a third step, where a cyanine compound is produced by an anion exchange reaction with an organic or inorganic anion. The production of cyanine compounds is described, for example, in US Pat. No. 6,589,706, the disclosure of which is hereby incorporated by reference.

In a further embodiment, the salt of the invention comprises the following steps:
(A) at least partially dissolving at least one anionic xanthene compound in an aqueous solvent to provide a xanthene solution;
(B) adding the xanthene solution to another solution containing at least one cationic cyanine compound to form a precipitate;
(C) filtering the resulting precipitate;
(D) optionally by washing with water.

  In a more specific embodiment of this method of the invention, the anionic xanthene compound is at least 1-20% by weight of the solution, preferably at least 1-10% by weight, more preferably at least 2-7% by weight, especially at least Present in the xanthene solution of step (a) in an amount of 5% by weight. In some embodiments, at least a portion of the anionic xanthene compound may be present in a dispersed state in the solution and not all of the anionic xanthene is in solution. In step (b) of the method, the solution containing the anionic xanthene compound, optionally partially dispersed, may be added dropwise or more rapidly to the solution containing the cationic cyanine compound. , Preferably may be added dropwise. After the addition of the solution containing the anionic xanthene compound to the solution containing the cationic cyanine compound is complete, the salt containing the anionic xanthene compound and the cationic cyanine compound typically precipitates. In step (c), the precipitate may be recovered by any method known in the art, for example by filtration or centrifugation. The recovered precipitate is usually washed with water, typically washed.

  In the process of the present invention, the weight ratio of anionic xanthene compound to cationic cyanine compound is typically 2: 1, preferably 1.5: 1, and most preferably about 1: 1.

  In the method of the present invention, the solvents used to dissolve the anionic xanthene compound and the cationic cyanine compound may be the same or different, most often the same. As the solvent used for dissolving the anionic xanthene compound and / or the cationic cyanine compound, any solvent known in the art may be used, but a water-miscible solvent such as water or alcohol, or A mixture thereof is generally used.

  The salts according to the invention are particularly suitable as dyes, in particular as violet dyes. According to another embodiment of the present invention, a paste pigment composition for a color filter is used as a violet colorant, mixing the salt of the present invention with at least one other dye or pigment; and kneading May be prepared. Such a kneaded pigment composition can be used as such, but if necessary it can also be used together with different types of organic or inorganic pigments, preferably organic pigments. When different types of blue organic pigments are used together with the kneaded pigment composition described herein, the kneaded pigment composition is used as the main component because it provides a better contrast ratio and brightness It is desirable to do.

  The kneaded pigment composition comprises a binder, a polymer-based dispersion aid, a dispersant, a liquid medium, and the like, as described in US Pat. No. 7,368,148, which is incorporated herein by reference in its entirety. Additional additives such as a mixture may be included.

  For example, a solvent such as butanol, a dispersant, and a binder (polymer or resin material) are mixed. The salt of the present invention may then be added while stirring the mixture. The resulting mixture is then subjected to milling to micronize the component particles. In some embodiments of the present invention, milling can be performed in at least two steps that utilize milling beads having different sizes. In a specific embodiment, milling is first performed in the presence of large beads and then in the presence of small beads. After the milling step, the beads are removed by a suitable separation means such as a glass filter, and the kneaded pigment composition is recovered.

  The present invention is also directed to a violet colorant comprising a colorant, preferably a salt according to the invention described above. The colorant may further comprise at least another dye or pigment, for example a blue pigment such as ε-type copper phthalocyanine particles or a violet pigment such as PV-23. It also includes compositions for color filters comprising the salts or colorants of the present invention, and optionally from the salts or colorants of the present invention and optionally binders, polymer-based dispersion aids, dispersants and liquid media. The present invention relates to a kneaded pigment composition for a color filter, which comprises an optional additive selected from the group consisting of: The invention therefore also relates to a color filter comprising said colorant. Such a color filter may be produced by lithographic methods, in particular by the following steps: a step of applying the kneaded pigment composition according to the present invention on a substrate, a step of drying, a step of exposing and a step of developing. The color filter can be applied for manufacturing a solid-state imaging device such as a liquid crystal display device, an LED display device, or a charge coupled device (CCD).

  The invention therefore also relates to the use of the salts according to the invention as dyes, preferably as violet dyes, and for the production of color filters, in particular for forming the blue part of color filters. That is, it relates to the use of colorants.

  In the event that the disclosure of any patents, patent applications, and publications incorporated herein by reference contradicts the description of this application to the extent that they may obscure the terms, the description shall control. And

Example 1 (Production of cyanine compound)
Synthesis of trimethylindolenine 80 g phenylhydrazine and 53 g 3-methyl-2-butanone were added to 400 mL acetic acid and the mixture was stirred at 100 ° C. for 3 hours. The resulting mixture was then cooled and filtered to remove solid byproducts. The filtrate was mixed with methylene chloride and the mixture was then poured into water. The product was recovered by extraction in the methylene chloride fraction and the methylene chloride was then evaporated. The yield of trimethylindolenine was 90.8% (80 g).

Synthesis of trimethylindolium iodide The resulting trimethylindolenine and 102 g of n-butyl iodide were added to 150 mL of o-chlorobenzene. The mixture was stirred at 100 ° C. for 24 hours. After the reaction, the resulting mixture was cooled and the product was extracted from the mixture with hot water. Water was evaporated to give the product. The reaction yield of trimethylindolium iodide was 77.1% (133 g).

Synthesis of Cyanine Compound The resulting trimethylindolium iodide and 86.1 g of trimethyl orthoformate were added to 250 mL of pyridine. The mixture was stirred at 100 ° C. for 3 hours and then allowed to cool to room temperature. This mixture was used in Example 3 without further purification.

Example 2 (Production of xanthene compound)
Synthesis of xanthene dye compound 22.14 g of dibutylaminophenol and 15.6 g of formyl-2,4-disulfonic acid disodium salt were added to 2 g of p-toluenesulfonic acid, and the mixture was stirred at 120 ° C. for 3 hours. The resulting mixture is then cooled and filtered by using a mixture with water / ethanol (1: 1) to remove salts, washed with water / ethanol (1: 1) and the filtrate evaporated. I let you. The reaction yield was 60%.

Example 3 (Production of the salt of the present invention)
The xanthene compound prepared according to Example 2 was dispersed in water to reach a concentration of 5%. To the resulting mixture of Example 1, 2640 mL of a 5 wt% dispersion of xanthene was added dropwise, which resulted in precipitation of the product. After complete addition of the xanthene dispersion, the precipitate was filtered and washed several times with water to give the product. The reaction yield of the salt was 60% (64.5 g).

Example 4 (Preparation of a kneaded pigment composition)
A kneaded pigment composition was prepared by heating as needed to dissolve the methacrylate-based dispersant (10 parts) in 70 parts ethanol containing 6 parts methacrylate-based binder. 3 mm diameter crow beads (100 parts), ε-type copper phthalocyanine particles (10 parts), and the salt obtained in Example 3 (2 parts) were added, and milling was carried out for 24 hours on a horizontal shaker and kneaded pigment A composition was obtained.

Comparative Example 1 (Preparation of a control kneaded pigment composition containing Pigment Violet 23)
A paste pigment composition was prepared according to the same method as Example 4, except that Pigment Violet 23 (PV 23) was used instead of the salt of Example 3.

Example 5 (color filter test)
A color filter manufactured using the kneaded pigment composition according to Example 4 was manufactured in Comparative Example 1 in which Pigment Violet 23 (PV 23) was used in place of the salt of the present invention, as shown in Table 1. Compared to what was produced, it produced an improvement in contrast ratio and brightness by approximately 20% and 3%, respectively.

  As shown in the color property results below, the salts of the present invention used as violet colorants in kneaded pigments have improved performance compared to Pigment Violet 23 typically used as violet pigments in the prior art. Represent.

Industrial application The salts according to the invention have the advantage of having improved thermal stability. The salts according to the invention also make it possible to produce color filters with improved performance, in particular in terms of brightness. The salts of the present invention are not only for liquid crystal displays (LCDs) but also for subtractive color generation, such as in electro-optic systems such as charge coupled devices, plasma displays or electroluminescent displays. Is useful as a colorant for color filters, and also as a colorant for electronic ink ("e-ink") or electronic paper ("e-paper").

  It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit and scope of the invention. Accordingly, the present invention is intended to embrace modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims (15)

  A salt comprising at least one cationic cyanine compound as a cation and at least one anionic xanthene compound as an anion. The anionic xanthene compound has the formula (I)
[Where:
Each of R1, R2, R3 and R4 is the same or different and is independently hydrogen and an alkyl having 1 to 4 carbon atoms; preferably 1 to 2; more preferably 2 carbon atoms Selected from the group consisting of, cycloalkyl and aralkyl;
-M is 2-5, especially 2-4, more especially 2 or 3.]
The salt of Claim 1 represented by these. The cationic cyanine compound has the formula (II)
[Where:
A and B are each the same or different and are independently aromatic, heteroaromatic and polyaromatic rings having 3 to 20 carbon atoms, preferably 6 to 16 carbon atoms, in particular benzene Or selected from the group consisting of naphthalene, said group optionally substituted with fluorinated or non-fluorinated alkyls;
Each R5 and R6 is the same or different and is independently 1 to 30, optionally substituted with another atom, preferably alkyl or halogen, more preferably fluorine, preferably Selected from the group consisting of alkyl, alkoxy and hydroxyalkyl having 2-20, most preferably 4-15 carbon atoms;
X ₁ , X ₂ , X ₃ and X ₄ may be any kind of substituent, preferably hydrogen or alkyl, optionally substituted with halogen, preferably fluorine;
Y ₁ , Y ₂ and Y ₃ are each the same or different and are independently selected from the group consisting of hydrogen, halogen, cyano, nitro, alkyl, and aryl groups, taken together as 5 or 6 May form a member ring;
-N is 1-5]
The salt of Claim 1 or 2 represented by these. Each of R1, R2, R3 and R4 is the same or different, preferably the same and is independently alkyl having 1 to 4 carbon atoms, preferably methyl, ethyl, n-propyl, i Selected from the group consisting of -propyl, n-butyl, i-butyl and t-butyl, more preferably ethyl;
The salt according to any one of claims 1 to 3, wherein m is 2 to 3, especially 2. 5. The method according to claim 1, wherein when at least two SO ₃ ^— groups are present, said at least one SO ₃ ^— group is in ortho or para, preferably at least in both ortho and para. The described salt. The anionic xanthene compound has the formula (I-1)
The salt as described in any one of Claims 1-5 represented by these. Y _1, at least one of Y ₂ and Y ₃ is cyano or halogen, preferably cyano or chlorine, salt according to any one of claims 1 to 6. The salt according to any one of claims 1 to 7, wherein at least one of X _{1 to} X ₄ , R5 and R6 is alkyl substituted with at least one fluorine atom. The cationic cyanine compound is any one of formulas (II-1) to (II-6), preferably formula (II-6)
The salt as described in any one of Claims 1-8 represented by these. (A) at least partially dissolving at least one anionic xanthene compound in an aqueous solvent to provide a xanthene solution;
(B) adding the xanthene solution to another solution containing at least one cationic cyanine compound to form a precipitate;
(C) filtering the resulting precipitate;
(D) The manufacturing method of the salt as described in any one of Claims 1-9 including the process of washing | cleaning with water optionally.   Colorant comprising a salt according to any one of claims 1-9 and optionally at least another dye or pigment, preferably a violet colorant.   The composition for color filters containing the salt as described in any one of Claims 1-9, or the coloring agent of Claim 11.   Any addition selected from the group consisting of a binder, a polymer-based dispersion aid, a dispersant and a liquid medium, comprising the salt according to any one of claims 1 to 9 or the colorant according to claim 11. A kneaded pigment composition for a color filter, optionally containing an agent.   Use of a salt according to any one of claims 1 to 9 or a colorant according to claim 11 for the manufacture of a color filter.   10. Use of a salt according to any one of claims 1 to 9 as a dye, in particular as a violet dye.