JP2010002746A - Red ink composition for color filter and color filter using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a red ink composition for color filters capable of improving the impact position accuracy of ink by a lowered pigment concentration, and a color filter using the same. <P>SOLUTION: The red ink composition for color filters contains at least two pigments selected from C.I. Pigment Red 242, C.I. Pigment Red 254 and C.I. Pigment Red 177 and does not contain a yellow pigment. The color filter using the same is also provided. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a red ink composition useful for a color filter and a color filter using the same.

In recent years, with the development of personal computers, in particular with the development of portable personal computers, the demand for liquid crystal displays, particularly color liquid crystal displays, has increased dramatically. As a method for producing a color filter used for this liquid crystal display, a pigment dispersion method, a dyeing method, an electrodeposition method, a printing method, an ink jet method and the like are known.
For example, in the pigment dispersion method, a photosensitive resin layer in which a pigment is dispersed is first formed on a substrate and patterned to obtain a monochromatic pattern. Further, by repeating the process three times, a colored layer of three colors of R (red), G (green), and B (blue) is formed.
In the dyeing method, a photosensitive agent is added to a water-soluble polymer material that is a dyeing material on a glass substrate to sensitize it, and the resulting pattern is patterned into a desired shape by a photolithography process. Immerse in a dyeing bath to obtain a colored pattern. This is repeated three times to form R, G, and B colored layers.
In the electrodeposition method, first, a transparent electrode is patterned on a substrate. Next, the first color is electrodeposited by dipping in an electrodeposition coating solution containing a pigment, a resin, an electrolytic solution and the like. This process is repeated three times to form R, G, and B colored layers, and finally fired.
In the printing method, a paint in which a pigment is dispersed in a thermosetting resin is separately applied to three colors R, G, and B by repeated printing, and then the resin that is the colored layer is heat-cured to form a colored layer.
In any of these methods, the process of obtaining a monochromatic pattern is repeated three times to form a colored layer of three colors of R, G, and B, so that the number of processes is large and complicated.
On the other hand, in the ink jet method, three color inks of R, G, and B can be ejected in the same process to form a colored layer of three colors, so that the process can be reduced.

Examples of the red ink composition for a color filter used in the ink jet method include C.I. I. Pigment red 254, C.I. I. Pigment red 177, and C.I. I. Ink-jet inks for color filters containing a pigment containing at least pigment yellow 150, a binder, and a solvent have been proposed.
However, when a high shear stress is applied to the color filter ink-jet ink, the dispersion stability state of the pigment in the ink is lost, the ink aggregates, and the ink aggregate may adhere to the ink jet discharge holes. Further, there is a problem that the discharge amount is not stable when the thixotropic property of the ink is increased. Further, when the amount of the dispersant in the ink is increased, drying is promoted, and the above aggregation and adhesion may be further promoted.
As described above, when ink aggregates adhere to the ink jet discharge holes as foreign matter, the ink landing position accuracy is lowered, and in combination with the unstable discharge amount, color mixing of the color filter coloring layer and uneven landing amount occur. This will cause the problem of reducing the quality of the filter.
The color mixing of the colored layer and the occurrence of uneven landing amount were likely to occur in the red ink composition for color filters.

JP 2007-124202 A

As a result of various studies to solve the above problems, the present inventors have improved the ink landing position accuracy by reducing the pigment concentration of the red ink composition for the color filter, and the mixed color of the colored layer and uneven landing amount are reduced. It has been found that the occurrence of the occurrence can be prevented.
Accordingly, an object of the present invention is to reduce the pigment concentration of the red ink composition for a color filter and improve the ink landing position accuracy.

As a result of further studies to achieve the above problems, the present inventors can suitably reduce the pigment concentration by removing the yellow pigment from the red ink composition for color filters, and can achieve the above problems. I found. The present invention has been completed based on such findings.
That is, the present invention
[1] C.I. I. Pigment red 242, C.I. I. Pigment red 254, C.I. I. A red ink composition for a color filter, comprising at least two pigments of CI Pigment Red 177 and not containing a yellow pigment;
[2] The red ink composition for a color filter according to the above [1], having PR242 and having at least one pigment selected from PR254 and PR177,
[3] The red ink composition for color filters as described in [1] or [2] above, wherein the pigment concentration is 45% by mass or less,
[4] The red ink composition for color filters as described in any one of [1] to [3] above, wherein the content of the dispersant in the solid content of the composition is 30% by mass or less, and [5] A color filter formed by an inkjet method using the red ink composition according to any one of [1] to [4].

  ADVANTAGE OF THE INVENTION According to this invention, the pigment density | concentration can be made low and the red ink composition for color filters which can improve the landing position precision of an ink, and a color filter using the same can be provided.

The red ink composition for a color filter of the present invention includes C.I. I. Pigment red 242, C.I. I. Pigment red 254, C.I. I. Pigment Red 177 has at least two pigments and does not contain a yellow pigment. Since the yellow pigment has a lower coloring power than the red pigment, if the yellow pigment is removed, a coloring power equivalent to that of the red pigment can be obtained even at a low pigment concentration. Here, the pigment concentration refers to the content (% by mass) of the pigment in the solid content of the red ink composition for a color filter.
Hereinafter, C.I. I. Pigment Red is abbreviated as “PR”. I. Pigment Orange is abbreviated as “PO”. I. Pigment Violet is abbreviated as “PV” and C.I. I. Pigment Yellow is abbreviated as “PY”.
The red ink composition for a color filter of the present invention preferably has PR242 and at least one pigment selected from PR254 and PR177. This is because use of PR242 enables high brightness and high contrast.

  As a red pigment used in the red ink composition for a color filter of the present invention, in addition to the above PR242, PR254, and PR177, a red pigment described below may be added as desired. Specifically, PR1, PR2, PR3, PR4, PR5, PR6, PR7, PR8, PR9, PR10, PR11, PR12, PR14, PR15, PR16, PR17, PR18, PR19, PR21, PR22, PR23, PR30, PR31 PR32, PR37, PR38, PR40, PR41, PR42, PR48: 1, PR48: 2, PR48: 3, PR48: 4, PR49: 1, PR49: 2, PR50: 1, PR52: 1, PR53: 1, PR57 PR57: 1, PR57: 2, PR58: 2, PR58: 4, PR60: 1, PR63: 1, PR63: 2, PR64: 1, PR81: 1, PR83, PR88, PR90: 1, PR97, PR101, PR102 , PR104, PR105, PR106, PR108, PR 12, PR113, PR114, PR122, PR123, PR144, PR146, PR149, PR150, PR151, PR166, PR168, PR170, PR171, PR172, PR174, PR175, PR176, PR178, PR179, PR180, PR185, PR187, PR188, PR190, PR193, PR194, PR202, PR206, PR207, PR208, PR209, PR215, PR216, PR220, PR224, PR226, PR243, PR245, PR255, PR264, PR265, and the like.

  In addition to the red pigment, an orange pigment or a violet pigment may be added as desired within a range that meets the object of the present invention. Examples of the orange pigment include PO1, PO5, PO13, PO14, PO16, PO17, PO24, PO34, PO36, PO38, PO40, PO43, PO46, PO49, PO51, PO61, PO63, PO64, PO71, and PO73. Moreover, as a violet pigment, PV1, PV19, PV23, PV29, PV32, PV36, PV38 etc. are mentioned, for example.

The red ink composition for a color filter of the present invention is a composition obtained by blending a dispersant, a binder, a photopolymerization initiator added as necessary, and a solvent in addition to the above-mentioned pigment.
The red ink composition for a color filter of the present invention may be produced by adding each component to a solvent that is a single solvent or a mixed solvent, and mixing and dissolving or dispersing the solid component. In many cases, the pigment cannot be sufficiently dispersed in the solvent when it is directly put into the whole solvent together with other components and mixed with stirring.
Therefore, a pigment dispersion is usually produced by mixing a pigment, a dispersant, and a solvent. A binder, a photopolymerization initiator that is added as needed, and a solvent that is further added as needed are added to the pigment dispersion. A red ink composition is obtained by mixing.
If necessary, a part of the binder component may be mixed during the production of the pigment dispersion for the purpose of improving the dispersibility of the pigment.
Examples of the mixing means for obtaining the pigment dispersion and the red ink composition include a mixing and dispersing machine such as a paint shaker, a bead mill, a ball mill, a dissolver, and a kneader.
The pigment concentration of the red ink composition for a color filter of the present invention is preferably 45% by mass or less, more preferably 40% by mass or less, in order to improve the ink landing position accuracy, and more preferably 25 to 38%. It is particularly preferable that the content is% by mass.

The dispersant according to the present invention is blended in the inkjet ink in order to disperse the pigment satisfactorily. As the dispersant, for example, cationic, anionic, nonionic, amphoteric, silicone based surfactants and the like can be used. Among these, a polymer dispersant (polymer surfactant) is preferable. Further, a dispersion auxiliary resin such as a special acrylic polymer may be further used.
Examples of the polymer dispersant include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, and polyoxyethylene oleyl ether; polyoxyethylene octyl phenyl ether, polyoxyethylene nonyl phenyl ether, and the like. Polyoxyethylene alkylphenyl ethers; polyethylene glycol diesters such as polyethylene glycol dilaurate and polyethylene glycol distearate; sorbitan fatty acid esters; fatty acid-modified polyesters; tertiary amine-modified polyurethanes and the like.
Commercially available polymer dispersants include trade names “Disperbyk-161”, “Disperbyk-162”, “Disperbyk-163”, “Disperbyk-164”, “Disperbyk-166”, “Disperbyk-167”, “ Disperbyk-182 "," Disperbyk-2000 "," Disperbyk-2001 "(all manufactured by Big Chemie) and the like.

  The content of the dispersant in the solid content of the red ink composition for a color filter of the present invention is preferably 30% by mass or less, more preferably 5 to 25% by mass, and 10 to 25% by mass. It is particularly preferred. This is because when the content of the dispersant in the solid content of the red ink composition is 30% by mass or less, drying of the red ink composition is suppressed, and ink agglomerates are hardly generated.

The binder according to the present invention is used for the purpose of imparting film-forming properties and adhesion to the coated surface to the red ink composition.
Since the red ink composition according to the present invention is an ink composition used in an ink jet system, in order to form a predetermined pattern, the ink composition is selectively attached only to a predetermined pattern formation region and solidified. It is not necessary to form a pattern by performing exposure and development. Therefore, as the binder, it is not always necessary to use a photocurable binder that can be exposed and developed, and a non-curable thermoplastic resin composition may be used, but a binder containing a curable resin may be used. This is preferable because sufficient hardness is imparted to the cured film.

  Examples of the curable binder include a thermosetting binder including a thermosetting resin that can be polymerized and cured by heating, and light including a photocurable resin that can be polymerized and cured by visible light, ultraviolet light, an electron beam, and the like. A curable binder, and further, one containing both a thermosetting binder and a photocurable binder can be used. In the red ink composition according to the present invention, the binder is thermosetting from the viewpoint of improving the film physical properties of the pixel such as solvent resistance, adhesion, and ITO resistance even when the pigment concentration is increased. A binder is preferred. In addition, ITO tolerance here is tolerance with respect to the malfunction at the time of ITO circuit formation or alignment film formation, and specifically, the heat resistance in 230-250 degreeC after ITO circuit formation is mentioned. In addition, when a thermosetting binder is used, there is an advantage that a special incidental equipment such as a light irradiation device is not necessary and productivity is high.

  As the thermosetting binder, a combination of a compound having two or more thermosetting functional groups in one molecule and a curing agent is usually used, and a catalyst capable of accelerating the thermosetting reaction may be added. An epoxy group is preferably used as the thermosetting functional group. Further, these may further contain a polymer which is not polymerized by itself.

  As a compound having two or more thermosetting functional groups in one molecule, from the viewpoint of film ejection properties of ink jet and film physical properties such as solvent resistance, adhesion and ITO resistance of pixels formed by the ink jet ink, 1 Epoxy compounds having two or more epoxy groups in the molecule are preferably used. An epoxy compound having two or more epoxy groups in one molecule is an epoxy compound having two or more, preferably 2 to 50, more preferably 2 to 20 epoxy groups in one molecule (referred to as an epoxy resin). Is included). The epoxy group should just be a structure which has an oxirane ring structure, for example, can show a glycidyl group, an oxyethylene group, an epoxycyclohexyl group, etc. Examples of the epoxy compound include known polyvalent epoxy compounds that can be cured by carboxylic acid. Examples of such an epoxy compound include “Epoxy resin handbook” edited by Masaki Shinbo, published by Nikkan Kogyo Shimbun (Showa 62). These can be used widely.

  As an epoxy compound suitably used for the binder according to the present invention, in order to impart solvent resistance and heat resistance to the cured film, the polymer having a relatively high molecular weight and the crosslinking density of the cured film are increased or reduced. In order to improve inkjet discharge performance by increasing the viscosity, it is preferable to use a compound having a relatively low molecular weight.

  As an epoxy resin (hereinafter referred to as “binder epoxy resin”) that is a polymer having a relatively high molecular weight that is usually used as a binder component, at least the structural unit represented by the following formula (1) and the following formula (2): The polymer comprised from the structural unit represented by these can be used.

（式中、Ｒ¹は水素原子又は炭素数１〜３のアルキル基であり、Ｒ²は炭素数１〜１２の炭化水素基である。）

(In the formula, R ¹ is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R ² is a hydrocarbon group having 1 to 12 carbon atoms.)

（式中、Ｒ³は水素原子又は炭素数１〜１０のアルキル基である。）

(In the formula, R ³ is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms.)

By using the structural unit represented by the above formula (1), sufficient hardness and transparency can be imparted to the cured coating film formed from the red ink composition of the present invention. In the formula (1), R ² may be a linear aliphatic, alicyclic or aromatic hydrocarbon group, and further has an additional structure such as a double bond, a side chain of a hydrocarbon group, It may contain a side chain of a spiro ring, an intra-ring bridged hydrocarbon group or the like.
In formula (1), R ¹ is preferably a hydrogen atom or a methyl group, and R ² is preferably an alkyl group having 1 to 12 carbon atoms. Among them, a methyl group and a cyclohexyl group are particularly preferable. .

The structural unit represented by the above formula (1) is formed by using the monomers exemplified below. That is, methyl (meth) acrylate, ethyl (meth) acrylate, i-propyl (meth) acrylate, n-propyl (meth) acrylate, i-butyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl ( (Meth) acrylate, 2-ethylhexyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, lauryl (meth) acrylate, cyclohexyl (meth) acrylate, para-t-butylcyclohexyl (meth) acrylate, isobornyl (meth) ) Acrylate, benzyl (meth) acrylate, dicyclopentenyl (meth) acrylate, phenyl (meth) acrylate, and the like. Among these, particularly preferred monomers include methyl methacrylate (MMA) and cyclohexyl methacrylate (CHMA).
Here, (meth) acrylate includes both acrylate and methacrylate.

When the binder epoxy resin has the structural unit represented by the above formula (2), two or more glycidyl groups are introduced into the binder epoxy resin to impart thermosetting properties, and the red ink composition of the present invention. The storage stability of the ink becomes good, and the viscosity is hardly increased during storage and discharging.
In the above formula (2), R ³ is preferably hydrogen or a methyl group. Specific examples of the monomer used for introducing the structural unit represented by the above formula (2) include glycidyl (meth) acrylate, and glycidyl methacrylate (GMA) is particularly preferable.

  The binder epoxy resin may be a random copolymer or a block copolymer. In addition, the binder epoxy resin includes main chain constituent units other than formula (1) or formula (2) as long as performance required for each detail of the color filter, such as hardness and transparency, can be ensured. May be. Specific examples of the monomer that forms such a structural unit include acrylonitrile and styrene.

The content of the structural unit of formula (1) and the structural unit of formula (2) in the binder epoxy resin is derived from the monomer that derives the structural unit of formula (1) and the structural unit of formula (2). When expressed in terms of the charged mass ratio to the monomer (the monomer that derives the formula (1): the monomer that induces the formula (2)), it is in the range of 10:90 to 90:10. preferable.
If the content of the structural unit of the formula (1) and the structural unit of the formula (2) is within the range of the charged mass ratio, there is no fear that the curing reaction point is secured and the crosslinking density is lowered, while the bulk is high. This is preferable because the skeleton is also secured and there is no fear that curing shrinkage will increase.

  The weight average molecular weight of the binder epoxy resin is preferably 3,000 or more, particularly 4,000 or more, when expressed in terms of polystyrene-converted weight average molecular weight. If the weight average molecular weight of the binder epoxy resin is 3,000 or more, physical properties such as strength and solvent resistance required for the cured layer as the details of the color filter are secured. On the other hand, the weight average molecular weight of the binder epoxy resin is preferably 20,000 or less, more preferably 15,000 or less, when expressed in terms of polystyrene-converted weight average molecular weight. When the molecular weight is 20,000 or less, viscosity increase is unlikely to occur, and the stability of the ejection amount and the landing position accuracy (straightness in the ejection direction) when ejected from the ejection head by the ink jet method are improved, and long-term storage This is because the stability is improved.

  As the binder epoxy resin, a polystyrene-reduced weight average molecular weight (Mw) is in the above range, and a GMA / MMA copolymer polymerized using at least glycidyl methacrylate (GMA) and methyl methacrylate (MMA) is used. Is particularly preferred. The GMA / MMA copolymer may be polymerized by containing other monomer components as long as the object of the present invention can be achieved.

  As an example of synthesis of the binder epoxy resin, for example, a solvent containing no hydroxyl group is charged into a four-necked flask equipped with a thermometer, a reflux condenser, a stirrer, and a dropping funnel, and the temperature is raised to 120 ° C. while stirring. . The reason for using a solvent that does not contain a hydroxyl group is to avoid the decomposition of the epoxy group during the synthesis reaction. Next, a monomer that forms the structural unit represented by the above formula (1), a monomer that forms the structural unit represented by the above formula (2), and a composition in which other monomers are combined as required, and polymerization start The mixture of the agents (dropping component) is dropped at a constant rate from the dropping funnel over 2 hours. After completion of the dropping, the temperature is lowered to 120 ° C., a catalyst is added, the reaction is performed for 3 hours, and the reaction is terminated when the temperature is raised to 130 ° C. and kept for 2 hours, whereby the binder epoxy resin is obtained.

  The thermosetting binder according to the present invention is an epoxy compound having two or more epoxy groups in one molecule (hereinafter referred to as “polyfunctional epoxy compound”), and has a molecular weight smaller than that of the binder epoxy resin. A thing may be used. Especially, it is preferable to use the said binder epoxy resin and the said polyfunctional epoxy compound together as mentioned above. In this case, the polystyrene equivalent weight average molecular weight of the polyfunctional epoxy compound is preferably 4,000 or less, particularly preferably 3,000 or less, on condition that it is smaller than the binder epoxy resin combined therewith.

  Since the epoxy resin (glycidyl group) is introduced into the binder epoxy resin by the structural unit represented by the formula (2), the amount of epoxy that can be introduced into the molecule of the copolymer is limited. When a polyfunctional epoxy compound having a relatively low molecular weight is added to the red ink composition of the present invention, epoxy groups are replenished in the red ink composition to increase the reaction point concentration of the epoxy, and the crosslinking density can be increased.

  Among polyfunctional epoxy compounds, it is preferable to use an epoxy compound having four or more epoxy groups in one molecule in order to increase the crosslink density of the acid-epoxy reaction. In particular, when the weight-average molecular weight of the binder epoxy resin is set to 10,000 or less in order to improve the discharge performance from the inkjet discharge head, the strength and hardness of the cured layer are likely to decrease. It is preferable to add a tetrafunctional or higher polyfunctional epoxy compound to the inkjet ink to sufficiently increase the crosslinking density.

  The polyfunctional epoxy compound is not particularly limited as long as it contains two or more epoxy groups in one molecule. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, brominated bisphenol A type epoxy resin, Bisphenol S type epoxy resin, diphenyl ether type epoxy resin, hydroquinone type epoxy resin, naphthalene type epoxy resin, biphenyl type epoxy resin, fluorene type epoxy resin, phenol novolac type epoxy resin, orthocresol novolak type epoxy resin, trishydroxyphenylmethane type epoxy Resin, trifunctional epoxy resin, tetraphenylolethane type epoxy resin, dicyclopentadienephenol type epoxy resin, hydrogenated bisphenol A type epoxy resin, bisphenol A included Polyol type epoxy resins, polypropylene glycol type epoxy resins, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, glyoxal type epoxy resin, alicyclic epoxy resin, a heterocyclic epoxy resin, or the like can be used.

  More specifically, bisphenol A type epoxy resin such as “Epicoat 828” (made by Japan Epoxy Resin), bisphenol F type epoxy resin such as “YDF-175S” (made by Toto Kasei), Brominated bisphenol A type epoxy resin such as “YDB-715” (manufactured by Tohto Kasei Co., Ltd.), bisphenol S type epoxy resin such as “EPICLON EXA1514” (manufactured by Dainippon Ink & Chemicals, Inc.), trade name “YDC-1312” ”(Manufactured by Tohto Kasei Co., Ltd.), etc., naphthalene type epoxy resins such as“ EPICLON EXA4032 ”(manufactured by Dainippon Ink and Chemicals), trade name“ Epicoat YX4000H ”(manufactured by Japan Epoxy Resin), etc. Biphenyl type epoxy resin, trade name "Epicoat 157S7 Bisphenol A type novolac type epoxy resin such as “Japan Epoxy Resin Co., Ltd.”, phenol novolac type such as “Epicoat 154” (Japan Epoxy Resin Co., Ltd.), “YDPN-638” (manufactured by Toto Kasei Co., Ltd.) Epoxy resin, cresol novolac type epoxy resin such as trade name “YDCN-701” (manufactured by Toto Kasei Co., Ltd.), dicyclopentadiene phenol type epoxy resin such as trade name “EPICLON HP-7200” (manufactured by Dainippon Ink and Chemicals, Inc.) , Trishydroxyphenylmethane type epoxy resin such as trade name “Epicoat 1032H60” (manufactured by Japan Epoxy Resin), trifunctional epoxy resin such as trade name “VG3101M80” (manufactured by Mitsui Chemicals), trade name “Epicoat 1031S” ( (Japan Epoxy Resin) Tetraphenylolethane type epoxy resin, tetrafunctional epoxy resin such as trade name “Denacol EX-411” (manufactured by Nagase Kasei Kogyo Co., Ltd.), hydrogenated bisphenol A such as trade name “ST-3000” (manufactured by Toto Kasei Co., Ltd.) Type epoxy resin, glycidyl ester type epoxy resin such as trade name “Epicoat 190P” (manufactured by Japan Epoxy Resin Co., Ltd.), glycidyl amine type epoxy resin such as trade name “YH-434” (manufactured by Tohto Kasei Co., Ltd.), trade name “YDG” -414 "(manufactured by Toto Kasei Co., Ltd.) and the like, alicyclic polyfunctional epoxy compounds such as trade name" Epolide GT-401 "(manufactured by Daicel Chemical Industries), and heterocyclic rings such as triglycidyl isocyanate (TGIC) Examples thereof include a type epoxy resin. Further, if necessary, a trade name “Neotote E” (manufactured by Tohto Kasei Co., Ltd.) or the like can be mixed as an epoxy reactive diluent.

  Among these polyfunctional epoxy compounds, bisphenol A type novolak epoxy resin such as “Epicoat 157S70” (manufactured by Japan Epoxy Resin) and cresol such as “YDCN-701” (manufactured by Toto Kasei) A novolac type epoxy resin is particularly preferable.

  In the binder according to the present invention, the blending ratio of the binder epoxy resin and the polyfunctional epoxy compound blended as necessary is 10 to 90 parts by mass of the binder epoxy resin and 90 polyfunctional epoxy compound in mass ratio. It is preferable to mix | blend in the ratio of 10-10 mass parts, It is still more preferable to mix | blend 30-80 mass parts of binder-type epoxy resins, and the ratio of 70-20 mass parts of polyfunctional epoxy compounds, and 35% of binder-type epoxy resins are included. It is particularly preferable to blend ~ 75 parts by mass and 65 to 25 parts by mass of the polyfunctional epoxy compound.

The thermosetting binder used in the present invention is usually combined with a curing agent. As the curing agent, for example, a polyvalent carboxylic acid anhydride or a polyvalent carboxylic acid is used.
Specific examples of the polyvalent carboxylic acid anhydride include phthalic anhydride, itaconic anhydride, succinic anhydride, citraconic anhydride, dodecenyl succinic anhydride, tricarballylic anhydride, maleic anhydride, hexahydrophthalic anhydride, dimethyltetrahydro anhydride Aliphatic or alicyclic dicarboxylic anhydrides such as phthalic acid, hymic anhydride, and nadic anhydride; Fats such as 1,2,3,4-butanetetracarboxylic dianhydride, cyclopentanetetracarboxylic dianhydride Polyhydric carboxylic acid dianhydrides; aromatic polycarboxylic anhydrides such as pyromellitic anhydride, trimellitic anhydride, and benzophenone tetracarboxylic anhydride; ester groups such as ethylene glycol bistrimellitate and glycerin tristrimitate Containing acid anhydrides, particularly preferably aromatic polycarboxylic It can be mentioned anhydride. Moreover, the epoxy resin hardening | curing agent which consists of a commercially available carboxylic acid anhydride can also be used suitably.

  Specific examples of polyvalent carboxylic acids used in the present invention include aliphatic polyvalent carboxylic acids such as succinic acid, glutaric acid, adipic acid, butanetetracarboxylic acid, maleic acid, and itaconic acid; hexahydrophthalic acid, Aliphatic polycarboxylic acids such as 1,2-cyclohexanedicarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, cyclopentanetetracarboxylic acid, and phthalic acid, isophthalic acid, terephthalic acid, pyromellitic acid, trimellitic acid, Aromatic polyvalent carboxylic acids such as 1,4,5,8-naphthalene tetracarboxylic acid and benzophenone tetracarboxylic acid can be mentioned, and aromatic polyvalent carboxylic acids can be mentioned preferably.

  The above curing agents can be used singly or in combination of two or more. The compounding quantity of the hardening | curing agent used for this invention is the range of 1-100 mass parts normally per 100 mass parts of components (binder epoxy resin and polyfunctional epoxy compound) containing an epoxy group, Preferably it is 5-5. 50 parts by mass. If the blending amount of the curing agent is less than 1 part by mass, curing may be insufficient and a tough coating film may not be formed. Moreover, when the compounding quantity of a hardening | curing agent exceeds 100 mass parts, there exists a possibility that the adhesiveness with respect to the board | substrate of a coating film may be inferior.

In order to improve the hardness and heat resistance of the cured layer, a catalyst capable of promoting an acid-epoxy thermosetting reaction may be added to the thermosetting binder according to the present invention. As such a catalyst, a thermal latent catalyst that exhibits activity during heat curing can be used.
The heat-latent catalyst exhibits catalytic activity when heated, accelerates the curing reaction and gives good properties to the cured product, and is added as necessary. The thermal latent catalyst is preferably one that exhibits acid catalytic activity at a temperature of 60 ° C. or higher. As such, a compound obtained by neutralizing a protonic acid with a Lewis base, a compound obtained by neutralizing a Lewis acid with a Lewis base, Lewis Examples thereof include a mixture of an acid and a trialkyl phosphate, sulfonic acid esters, onium compounds and the like, and various compounds described in JP-A-4-218561 can be used. Specifically, (i) compounds obtained by neutralizing halogenocarboxylic acids, sulfonic acids, phosphoric mono- and diesters with various amines such as ammonia, monomethylamine, triethylamine, pyridine, ethanolamine, or trialkylphosphine (B) a compound obtained by neutralizing a Lewis acid such as BF ₃ , FeCl ₃ , SnCl ₄ , AlCl ₃ , ZnCl ₂ or the like with the aforementioned Lewis base, (c) methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, etc. Examples include primary alcohols, ester compounds with secondary alcohols, (d) primary alcohols, secondary monoalcohol phosphate monoester compounds, and phosphate diester compounds. Examples of the onium compound include an ammonium compound [R ₃ NR ′] ⁺ X ⁻ , a sulfonium compound [R ₃ SR ′] ⁺ X ⁻ , and an oxonium compound [R ₃ OR ′] ⁺ X ⁻ . Here, R and R ′ are each independently an alkyl group, an alkenyl group, an aryl group, an alkoxy group, or the like.
The thermal latent catalyst is usually blended at a ratio of about 0.01 to 10.0 parts by mass with respect to a total of 100 parts by mass of the compound having two or more thermosetting functional groups in one molecule and the curing agent. .

  In the binder according to the present invention, a photocurable binder containing a photocurable resin is used in the case where it is polymerized and cured by light such as ultraviolet rays or electron beams. The photocurable binder preferably contains a polymer having a relatively high molecular weight for the purpose of imparting film formability and adhesion to the surface to be coated. Here, the relatively high molecular weight means that the molecular weight is higher than that of so-called monomers and oligomers, and the weight average molecular weight can be 5,000 or more. As a polymer having a relatively high molecular weight, any of a polymer having no polymerization reactivity per se and a polymer having a polymerization reactivity per se may be used, and two or more types may be used in combination. May be. The polymer is mainly composed of a relatively high molecular weight, and if necessary, it contains polyfunctional monomers and oligomers, monofunctional monomers and oligomers, photopolymerization initiators activated by light, and sensitizers. Thus, a photocurable binder is constituted.

  When a polymer having no polymerization reactivity is used as a polymer having a relatively high molecular weight, a polyfunctional polymerizable component such as a bifunctional or higher polyfunctional monomer or oligomer is added to the binder. In this case, in the binder, the polyfunctional polymerizable component itself is spontaneously polymerized by light irradiation or polymerized by the action of other components such as a photopolymerization initiator activated by light irradiation. A network structure is formed in the film, and components such as resins and pigments having no polymerization reactivity are enclosed in the network structure and cured.

As such a polymer having no polymerization reactivity, for example, a copolymer comprising two or more of the following monomers can be used: acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, 2-hydroxyethyl acrylate. 2-hydroxyethyl methacrylate, benzyl acrylate, benzyl methacrylate, styrene, polystyrene macromonomer, and polymethyl methacrylate macromonomer.
More specifically, methacrylic acid / benzyl methacrylate copolymer, methacrylic acid / benzyl methacrylate / styrene copolymer, benzyl methacrylate / styrene copolymer, benzyl methacrylate macromonomer / styrene copolymer, benzyl methacrylate / styrene macromonomer A copolymer etc. can be illustrated.

As a polymer having a polymerization reactivity per se, it is an oligomer obtained by introducing a polymerizable functional group into a polymer molecule having no polymerization reactivity or a polymer having a higher molecular weight than an oligomer, and is subjected to light irradiation. Those that cause a polymerization reaction per se or that induce a polymerization reaction by the action of other components such as a photopolymerization initiator activated by irradiation with light can be used.
Various ethylenic double bond-containing compounds themselves have polymerization reactivity and can be used as photocurable resins. Conventionally, prepolymers blended in UV inkjet inks used in various fields such as inks, paints and adhesives can be used as a polymer having a relatively high molecular weight in the present invention. Conventionally known prepolymers include radical polymerization type prepolymers, cationic polymerization type prepolymers, thiol / ene addition type prepolymers, and any of these may be used.

  Among these, radical polymerization type prepolymers are most easily available on the market, such as ester acrylates, ether acrylates, urethane acrylates, epoxy acrylates, amino resin acrylates, acrylic resin acrylates, unsaturated polyesters. Examples can be given.

Especially, the following graft polymers are mentioned as a comparatively high molecular weight polymer which can be used suitably in this invention.
The graft polymer suitably used in the present invention has a weight average molecular weight of 5,000 or more, and one of the main chain and the graft portion is composed of a styrenic polymer chain containing a styrenic monomer unit, and the other Is a graft polymer composed of methacrylate polymer chains containing methacrylate monomer units.

  The graft polymer may have a structure in which a main chain (trunk) is constituted by a styrene polymer chain and a graft part is constituted by a methacrylate polymer chain, and conversely, the main chain is constituted by a methacrylate polymer chain. And a structure in which a graft portion is constituted by a styrenic polymer chain. Among the above, those having a structure in which a main chain is constituted by a styrene polymer chain and a graft part is constituted by a methacrylate polymer chain are preferred.

The styrene polymer chain is a polymer chain mainly composed of a styrene monomer, and may be a homopolymer of only one kind of styrene monomer, or a copolymer of two or more kinds of styrene monomers. It may be a copolymer of a styrene monomer and another monomer.
The styrenic monomer includes styrene monomers having substituents such as alkyl-substituted styrene (methyl styrene, ethyl styrene, trimethyl styrene, octyl styrene, etc.), methoxy styrene, α-methyl styrene, etc. in addition to styrene.
Examples of the monomer that can be copolymerized with the styrene monomer include various (meth) acrylate monomers, acrylonitrile, amide monomers, and the like.

In the red ink composition of the present invention, from the viewpoint of pigment dispersibility, the styrene polymer chain preferably contains a styrene monomer unit in a proportion of 50% by mass or more, and more preferably in a proportion of 60% by mass or more. It is particularly preferable to do this.
The methacrylate polymer chain is a polymer chain mainly composed of methacrylate, and may be a homopolymer of only one kind of methacrylate, a copolymer of two or more kinds of methacrylate, or a methacrylate. And a copolymer of other monomers.

  As methacrylate monomers, alkyl methacrylate (methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, iso-butyl methacrylate, tert-butyl methacrylate, hexyl methacrylate, octyl methacrylate, lauryl methacrylate, etc.), benzyl methacrylate, phenoxyethyl methacrylate, tetrahydrophthalimide Examples include ethyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate, tetrahydrofurfuryl methacrylate, methoxypolyethylene glycol methacrylate, and butoxyethyl methacrylate. It is preferable to select and use a methacrylate monomer so that a graft polymer having a Tg of 30 ° C. or higher can be obtained. A graft polymer having a Tg of less than 30 ° C. is not preferable because the film hardness after curing decreases.

Moreover, as a monomer to be copolymerized with methacrylate, alkyl acrylate, hydroxyalkyl acrylate, amide monomer, imide group-containing monomer, alkylene glycol (meth) acrylate, Daicel Chemical's brand name Plexel FM series, or the like can be used.
The methacrylate polymer has a relatively high Tg and is excellent in hardness and dispersibility because it causes microphase separation from styrene. From this viewpoint, the methacrylate polymer chain preferably contains a methacrylate monomer unit in a proportion of 50% by mass or more, more preferably 70% by mass or more.

  The graft polymer may have a photopolymerizable functional group such as an ethylenically unsaturated bond or an epoxy group. Photocurability can be imparted by introducing a photopolymerizable functional group into the graft polymer. The graft polymer into which the photopolymerizable functional group has been introduced can be suitably used as a photocurable resin having a relatively high molecular weight in the present invention since the crosslinking point is improved and the surface hardness is improved. When the polymerizable functional group of the graft polymer is an ethylenically unsaturated bond, it can be cured by a photoradical polymerization reaction, and when the polymerizable functional group is an epoxy group, photocationic polymerization is possible. . In particular, when the graft polymer having an ethylenically unsaturated bond is used in combination with an ethylenically unsaturated bond-containing monomer such as a (meth) acrylic monomer and / or an oligomer, an inkjet ink having excellent reaction curability can be obtained. it can. The photopolymerizable functional group may be introduced into one or both of the styrenic polymer chain and the methacrylate polymer chain, or may be introduced into one or both of the main chain and the graft portion.

  Among them, the graft polymer has an ethylenically unsaturated bond in an ethylenically unsaturated bond equivalent of 1200 g / eq or less, and one of the main chain and the graft portion contains a styrene monomer unit. A preferred graft polymer is a graft polymer composed of a styrene methacrylate polymer chain and the other composed of a benzyl methacrylate polymer chain containing a monomer unit derived from benzyl methacrylate. Among the methacrylate monomers, benzyl methacrylate is particularly excellent in pigment dispersibility, and is therefore preferably used in a red ink composition for a color filter for forming pixels and the like.

The graft polymer may have a structure in which a main chain (trunk) is constituted by a styrene polymer chain and a graft part is constituted by a benzyl methacrylate polymer chain, and conversely, by a benzyl methacrylate polymer chain. It may have a structure in which the main chain is constituted and the graft portion is constituted by a styrene polymer chain. Among the above, those having a structure in which a main chain is constituted by a styrene polymer chain and a graft part is constituted by a benzyl methacrylate polymer chain are preferred.
The benzyl methacrylate polymer chain of the graft polymer is a polymer chain containing benzyl methacrylate as a main component, and may be a homopolymer of benzyl methacrylate or a copolymer of benzyl methacrylate and other monomers as described above. It may be a coalescence.
The benzyl methacrylate-based polymer chain preferably contains benzyl methacrylate monomer units in a proportion of 30% by mass or more, and particularly preferably contains 50% by mass or more.

  The graft polymer has at least one of the main chain or graft portion having an ethylenically unsaturated bond, and can be cured by light or thermal radical polymerization reaction. The ethylenically unsaturated bond equivalent of the graft polymer needs to be 1200 g / eq or less, and preferably 700 g / eq or less. Here, the ethylenically unsaturated bond equivalent is a value obtained by dividing the weight average molecular weight of the graft polymer by the number of ethylenically unsaturated bonds contained in one molecule. This is because when the ethylenically unsaturated bond equivalent of the graft polymer exceeds 1200 g / eq, the film hardness after curing and the solvent resistance may be insufficient. On the other hand, a graft polymer having an ethylenically unsaturated bond equivalent of 1200 g / eq or less is excellent in various physical properties such as solvent resistance, hardness, strength, and adhesion because there are many ethylenically unsaturated bonds contained in one molecule. is there. Even when a graft polymer having a relatively low molecular weight is used in order to improve the discharge property, it can be cured sufficiently if the ethylenically unsaturated bond equivalent is 1200 g / eq or less, so that the red color has excellent discharge property. This is because an ink composition can be obtained and a cured film having excellent physical properties can be formed.

The mass ratio of the graft (branch) portion / main chain (trunk) portion of the graft polymer is preferably 20/80 to 80/20, and more preferably 30/70 to 70/30. When the mass ratio of the graft portion is less than 20%, the solubility, viscosity, fluidity, dischargeability and the like are deteriorated, which is not preferable. On the other hand, when the mass ratio of the main chain portion is less than 20%, the pigment dispersibility deteriorates, which is not preferable.
Furthermore, by changing the acid value and amine value of the above graft polymer, various physical properties such as solubility in the solvent of the ink, solvent resistance of the film, dispersion stability of the pigment, dyeability, film hardness, film strength, etc. are adjusted. it can.

  The method for producing the graft polymer includes (1) a method in which a monomer is polymerized in the presence of a polymer and a peroxide catalyst, followed by grafting by hydrogen abstraction, and (2) a polymer having a functional group at one end and other functional groups. Although a method of addition reaction of a polymer with a mark and (3) a method of copolymerizing a polymerizable polymer (macromonomer) and a monomer can be used, the macromonomer method is preferred because the purity of the product is high. As a procedure for synthesizing the graft polymer, reference can be made to specific examples of paragraph numbers 0094 to 0105 of JP-A-2002-201387.

In addition, since the red ink composition of the present invention is an ink composition used for an ink jet system, the viscosity of the ink composition is too high so that the ejection performance from the ejection head is not adversely affected. The molecular weight of the polymer is preferably 25,000 or less in terms of weight average molecular weight.
The polymer having a relatively high molecular weight is preferably blended at a ratio of 1 to 50% by mass in the total solid content of the red ink composition.

In the red ink composition of the present invention, in order to improve the strength of the coating film and the adhesion to the substrate even when using a polymer having a relatively high molecular weight that can be polymerized and cured, It is preferable to blend a polyfunctional polymerizable component such as a monomer or oligomer. Polymer molecules with relatively high molecular weight that are polymerizable not only polymerize with polymers with relatively high molecular weight, but also polymerize with other polymerizable components such as polyfunctional monomers to form a network and cure. To do.
As the polyfunctional polymerizable component forming the network structure of the coating film, a bifunctional or higher functional monomer or oligomer can be used. In order to impart sufficient film strength and adhesion to the photocurable resin, a tetrafunctional or higher functional monomer or oligomer is usually used.

  However, in particular, since the red ink composition of the present invention is used as an ink composition of an ink jet system, as a polymerizable component other than a polymer having a relatively high molecular weight, a bifunctional to trifunctional monomer having a relatively small number of functional groups. Alternatively, an oligomer or a monomer is preferably used as a main component, and a bi- or trifunctional monomer having a viscosity of 100 cps or less is particularly preferable. During ink jet spraying, it is difficult for the viscosity to increase at the tip of the head, clogging of the head does not occur, and ink ejection during operation is stable, so the amount and direction of ink ejection is stable. This is because the ink can be accurately and uniformly deposited on the substrate in a predetermined pattern.

  Examples of the bifunctional to trifunctional monomers include 1,6-hexanediol diacrylate, ethylene glycol dimethacrylate, 1,4-butanediol diacrylate, neopentyl glycol diacrylate, tripropylene glycol diacrylate, and polyethylene glycol diester. Examples thereof include acrylate, polypropylene glycol diacrylate, trimethylolpropane triacrylate, and 3-butylene glycol dimethacrylate.

In the red ink composition of the present invention, the blending ratio of the bi- to trifunctional monomers is preferably 20 to 70% by mass in the total solid content of the red ink composition.
If the blending ratio of the bi- to trifunctional monomer is 20% by mass or more based on the total solid content, the red ink composition can be sufficiently diluted with the monomer so that the viscosity of the ink can be lowered from the beginning and increased after volatilization of the solvent component. It is possible to prevent the nozzles of the ink jet head from being clogged by preventing the ink from becoming too much. Moreover, if the blending ratio of the bi- or trifunctional monomer is 70% by mass or less based on the total solid content, the crosslinking density of the coating film is secured, and the solvent resistance, adhesion, and hardness of the coating film are improved. .

However, when all the polyfunctional monomers blended in the red ink composition of the present invention are di- or tri-functional monomers, viscosity increase due to drying of the ink composition hardly occurs. On the other hand, the strength of the cured layer obtained by curing the ink layer, adhesion to the substrate, solvent resistance, and the like may be insufficient. Therefore, by adding an appropriate amount of a tetrafunctional or higher polyfunctional monomer or oligomer together with the above bifunctional to trifunctional monomers, the crosslinking density can be increased, and sufficient film strength and adhesion can be imparted to the pattern of the cured layer. .
Examples of tetrafunctional or higher polyfunctional monomers and oligomers include pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, dipentaerythritol hexamethacrylate, and the like.

Moreover, in the photocurable binder used for the red ink composition of this invention, you may mix | blend a monofunctional monomer and an oligomer as needed for the purpose of viscosity adjustment.
Examples of monofunctional monomers and oligomers include vinyl monomers such as styrene and vinyl acetate, and monofunctional acrylic monomers such as n-hexyl acrylate and phenoxyethyl acrylate.

  In said photocurable binder, the photoinitiator which has activity with respect to the wavelength of the light source to be used is normally mix | blended. The photopolymerization initiator is appropriately selected in consideration of the difference in the reaction format of the binder and the polyfunctional monomer (for example, radical polymerization or cationic polymerization) and the type of each material. For example, 1-hydroxycyclohexyl-phenyl ketone 2,2-dimethoxy-1,2-diphenylethane-1-one, 2-methyl-1- [4- (methylthio) phenyl] -2-monforinopropan-1-one, 2-benzyl-2- Dimethylamino-1- (4-morpholinophenyl) -butan-1-one, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1- [4- (2-hydroxyethoxy) phenyl] 2-hydroxy-2-methyl-1-propan-1-one, 2,4,6-trimethylbenzoyldiphenyl-phosphine oxide, bisacylphosphine Oxide, benzoin ethyl ether, benzoin isobutyl ether, benzoin isopropyl ether, 2-isopropylthioxanthone, 2,4-diethylthioxanthone, 2- (3-dimethylamino-2-hydroxypropoxy) -3,4-dimethyl-9H-thioxanthone- 9-one mesochloride, benzophenone, methyl o-benzoylbenzoate, 4-benzoyl-4′-methyl-diphenyl sulfide, 3,3 ′, 4,4′-tetra (t-butylperoxycarbonyl), p-dimethyl Aminobenzoic acid ethyl ester, p-dimethylaminobenzoic acid isoamyl ester, 1,3,5-triacroylhexahydro-s-triazine, 2- [2- (5-methylfuran-2-yl) ethenyl] -4 , 6-Bis (trichloro Til) -s-triazine, 2- [2- (furan-2-yl) ethenyl] -4,6-bis (trichloromethyl) -s-triazine, methylbenzoylformate, 2,4,6-trimethylbenzoyldiphenyl A photopolymerization initiator such as phosphine oxide can be used.

The content of the photopolymerization initiator is preferably 0.1 to 5% by mass in the total solid content of the red ink composition, and 0.5 to 2% by mass in the total solid content. Further preferred.
In addition, in order to impart sufficient adhesion, strength and hardness to the cured ink layer, a thermosetting and / or photocurable binder occupying the total solid content of the red ink composition including the pigment and other components. The total proportion of the components is preferably 25% by mass or more.

In order to prepare the red ink composition for a color filter of the present invention so that the ink can be discharged from a high-concentration liquid or immediately from the head, a solvent is blended as necessary.
In order to prepare the red ink composition for a color filter of the present invention into a high-concentration ink for storage or an ink composition having a concentration that can be applied immediately, a solvent that suitably dissolves and disperses the solid content is particularly suitable. It is not limited.

The red ink composition for a color filter of the present invention has a boiling point of 180 ° C. to 260 ° C., particularly 210 ° C. to 260 ° C., and a vapor pressure at room temperature (particularly in the range of 18 ° C. to 25 ° C.) of 0.5 mmHg or less. It is preferable to use a solvent component of 0.1 mmHg or less as a main solvent, and to mix such a main solvent in a proportion of 70% by mass or more, particularly 80% by mass or more based on the total amount of the solvent. The surface tension of the main solvent is preferably 29 mN / m or more.
A solvent component having a boiling point of 180 ° C. to 260 ° C. and a vapor pressure at room temperature of 0.5 mmHg or less has an appropriate drying property and evaporation property. Therefore, when a single solvent or a mixed solvent containing such a solvent component at a high blending ratio is used, the red ink composition does not dry rapidly at the nozzle tip of the ejection head, so the viscosity of the ink composition increases rapidly. Clogging does not occur, and it is not necessary to adversely affect the straightness and stability of discharge. At the same time, since the drying proceeds at an appropriate speed after spraying on the surface to be ejected, the ink composition becomes familiar with the surface to be coated and the coated film surface becomes horizontal and smooth. The ink composition can be quickly and completely dried by the heating step. Compared to the case of using a wetting agent or a solvent having a very high boiling point, there is less possibility that the solvent remains in the coating film after the drying step.

If necessary, the organic solvent may contain a small amount of a solvent component other than the main solvent. However, even in that case, it is preferable to use the main solvent having the above boiling point and vapor pressure in a proportion of 70% by mass or more based on the total amount of the solvent. When the ratio of the main solvent is less than 70% by mass of the total amount of the solvent, there are cases where it is not possible to reliably obtain the drying property and the evaporation property suitable for the ink jet method.
It is desirable to use the main solvent at a blending ratio as high as possible, specifically, at least 70% by mass or more, preferably 80% by mass or more, and desirably 100% by mass as much as possible.

  The main solvent can be selected from the following solvents: ethylene glycol monoethyl ether, glycol ethers such as diethylene glycol diethyl ether; glycol ether esters such as ethylene glycol monomethyl ether acetate; diethylene glycol Glycol oligomer ethers such as monomethyl ether; glycol oligomer ether esters such as diethylene glycol monomethyl ether acetate; aliphatic or aromatic esters such as ethyl acetate, propyl benzoate; dicarboxylic acid diesters such as diethyl carbonate; Alkoxycarboxylates such as methyl 3-methoxypropionate; ketocarboxylates such as ethyl acetoacetate; ethanol Alcohols or phenols such as isopropanol and phenol; aliphatic or aromatic ethers such as diethyl ether and anisole; alkoxy alcohols such as 2-ethoxyethanol and 1-methoxy-2-propanol; diethylene glycol and tripropylene Glycol oligomers such as glycol; alkoxy alcohol esters such as 2-ethoxyethyl acetate; ketones such as acetone and methyl isobutyl ketone.

In addition, since the red ink composition for a color filter of the present invention contains a pigment, the main solvent that occupies most of the solvent is a solvent that does not contain a hydroxyl group from the viewpoint of dispersibility and dispersion stability of the pigment. It is preferable to use it.
Preferred solvents include ethylene glycol monobutyl ether acetate, diethylene glycol monobutyl ether acetate (BCA), diethylene glycol monoethyl ether acetate, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethyl adipate, dibutyl oxalate, dimethyl malonate, and malonic acid. Examples include diethyl, dimethyl succinate, and diethyl succinate. These solvents are preferable not only because they satisfy the requirements of a boiling point of 180 ° C. to 260 ° C. and a vapor pressure at room temperature of 0.5 mmHg or less, but also have no hydroxyl group in the molecule. Further, these solvents are mixed with or without being mixed with a highly dispersible solvent conventionally used for preparing pigment dispersions such as 3-methoxybutyl acetate and propylene glycol monomethyl ether acetate (PGMEA). It can be used as a solvent to prepare a pigment dispersion.

Further, when water is mixed in the solvent, the hydroxyl group of the water molecule is present in the solvent, so that the same problem as in the case of using the solvent having a hydroxyl group may be caused. Therefore, in order to substantially exclude moisture from the acid-epoxy crosslinking reaction system, it is preferable to prepare a red ink composition using an organic solvent having low miscibility with water. From this viewpoint, the solubility of the solvent for preparing the red ink composition in water is preferably 20 parts by mass or less with respect to 100 parts by mass of water having a liquid temperature of 20 ° C.
Among the main solvents mentioned as specific examples, diethylene glycol monobutyl ether acetate has no hydroxyl group, and its solubility in 100 parts by mass of water at a liquid temperature of 20 ° C. is low at 6.5 parts by mass. It is particularly preferable since it exhibits the property.

  The solvent is used in the proportion of 40 to 95% by mass in the total amount of the red ink composition containing the solvent to prepare the red ink composition. If the amount of the solvent is too small, the viscosity of the red ink composition is high and it becomes difficult to discharge from the inkjet head. If there is too much solvent, the ink film deposited on the wettability change site will be broken before the ink deposit amount (ink deposition amount) for the predetermined wettability change site (ink layer formation site) is not sufficient, It protrudes to the surrounding unexposed part and further spreads to the adjacent wettability change part (ink layer forming part). In other words, the amount of ink that can be deposited without sticking out from the wettability change site (ink layer forming site) to which the ink composition is to be deposited becomes insufficient, and the film thickness after drying is too thin. A sufficient transmission density cannot be obtained.

  As a method for adding the solvent, a solution having a composition obtained by subtracting the amount of the solvent used for preparing the pigment dispersion from the final composition of the whole solvent is diluted to the final concentration to complete the red ink composition. May be. Moreover, it is not necessary to add the solvent after that, using the whole solvent for preparation of a pigment dispersion liquid. Further, a high-concentration inkjet ink may be prepared by introducing the pigment dispersion into a relatively small amount of the main solvent. The high-concentration ink-jet ink can be stored as it is and diluted to the final concentration just before use and used in the ink-jet method.

The red ink composition for color filters of the present invention may contain one or more other additives as required. The following can be illustrated as such an additive.
a) Filler: For example, glass, alumina and the like.
b) Adhesion promoter: for example, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane.
c) Leveling agent: For example, vinyl polymers such as polyoxyalkylene surfactants, fatty acid ester surfactants, special acrylic polymers, vinyl ether polymers, and the like.
d) Ultraviolet absorber: For example, 2- (3-t-butyl-5-methyl-2-hydroxyphenyl) -5-chlorobenzotriazole, alkoxybenzophenone and the like.
e) Anti-aggregation agent: for example, sodium polyacrylate.

Next, the color filter of the present invention is formed by the ink jet method using the red ink composition of the present invention.
The color filter of the present invention comprises a transparent substrate and pixels formed on the transparent substrate, and at least one of these pixels is a pixel containing the red ink composition of the present invention.

  Here, the transparent substrate is not particularly limited as long as it is conventionally used for a color filter. For example, a flexible substrate such as quartz glass, Pyrex (registered trademark) glass, or synthetic quartz plate is used. A transparent flexible material having flexibility such as a transparent rigid material or a transparent resin film or an optical resin plate can be used. Among these, Corning 7059 glass is a material having a small coefficient of thermal expansion, excellent dimensional stability and workability in high-temperature heat treatment, and is an alkali-free glass containing no alkali component in the active matrix. Suitable for color filters for color liquid crystal display devices. In the present invention, a transparent substrate is usually used, but a reflective substrate or a white colored substrate can also be used. In addition, the substrate may be subjected to surface treatment for the purpose of preventing alkali elution, imparting a gas barrier property or other purposes as required.

  The pixel of the color filter of the present invention is usually formed with three colors of red (R), green (G), and blue (B). The coloring pattern shape in the pixel can be a known arrangement such as a stripe type, a mosaic type, a triangle type, or a four-pixel arrangement type, and the coloring area can be arbitrarily set.

The method for producing a color filter of the present invention includes a step of selectively depositing the red ink composition of the present invention on a predetermined region on a substrate by an ink jet method to form an ink layer, and curing the ink layer. Forming a pixel.
Since the color filter manufacturing method according to the present invention uses an inkjet method, cost reduction and yield improvement can be realized, and the manufacturing method is highly productive.

Examples The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.
The chromaticity x, chromaticity y and transmittance Y (%), contrast, and landing position accuracy of the red ink composition were evaluated according to the following methods.
<Chromaticity x, chromaticity y, and transmittance Y (%)>
Using a microspectrophotometer (trade name “OSP200”, manufactured by Olympus) and a C light source, the chromaticity x, chromaticity y and Y (brightness Y) value in the XYZ color system defined in JIS Z8701 Was measured as transmittance Y (%).
<Contrast>
A polarizing film was formed by bonding a polarizing film (manufactured by Nitto Denko, trade name “NPF-SEG1425DU”) on a 0.7 mm thick glass substrate (trade name “NA35”, manufactured by NH Techno Glass Co., Ltd.). A sample to be measured was obtained by sandwiching two polarizing plates so as to be orthogonal or parallel to each other so that the polarizing film side was the outside of the glass substrate on which the red pattern was formed. In the configuration of the measurement sample, the distance between the polarizing plate and the red pattern was 9.3 mm, and the distance between the polarizing plate and the glass substrate was 0 mm.
A backlight was turned on the measurement sample, and the luminance was measured. A measurement sample was prepared by setting the polarizing plates orthogonally and then in parallel, and each luminance was measured. The position where the luminance was measured in the sample was a position where the film thickness was uniform in the red pattern. As a device for measuring luminance in contrast measurement, a luminance meter (manufactured by Konica Minolta Sensing, trade name “LS-100”) equipped with a close-up lens (No. 153) was used. The viewing angle of the luminance meter was 1 °. The distance L from the close-up lens to the measurement sample was 710 mm.
<Position accuracy>
When the test red ink composition is ejected 100,000,000 drops from the inkjet head and the ink lands within a radius of 20 μm on a transparent substrate placed at a distance of 800 μm from the head, ○, the radius exceeds 20 μm, and the radius is less than 30 μm The case where the ink landed within the range of Δ was Δ, and the case where the ink landed within the radius of 40 μm or more was marked with ×.

Production Example 1 Synthesis of Binder Epoxy Resin In a four-necked flask equipped with a thermometer, a reflux condenser, a stirrer, and a dropping funnel, a solvent containing no hydroxyl group, diethylene glycol monobutyl ether acetate (also known as butyl), according to the formulation shown in Table 1. 40.7 parts by mass of carbitol acetate (hereinafter sometimes referred to as “BCA”) was added and heated with stirring to 140 ° C. Subsequently, 54.7 parts by mass of a mixture (dropping component) of a monomer having a composition described in Table 1 and a polymerization initiator (perbutyl O) at a temperature of 140 ° C. was dropped from the dropping funnel at a constant rate over 2 hours. After completion of the dropwise addition, the temperature was lowered to 110 ° C., and 4.6 parts by mass of a mixture of the polymerization initiator and solvent diethylene glycol monobutyl ether acetate (BCA) containing no hydroxyl group (additional catalyst component) was added, and the temperature at 110 ° C. was maintained for 2 hours. By the way, by terminating the reaction, a binder epoxy resin having a weight average molecular weight described in Table 1 was obtained.

［注］
１） パーブチルＯ：ｔ−ブチルパーオキシ２−エチルヘキサノエート（日本油脂（株）製）
２） 重量平均分子量：ゲル浸透クロマトグラフィーによるポリスチレン換算の値である。

[note]
1) Perbutyl O: t-butyl peroxy 2-ethylhexanoate (manufactured by NOF Corporation)
2) Weight average molecular weight: A value in terms of polystyrene by gel permeation chromatography.

Production Example 2 Preparation of Pigment Dispersion Each pigment, dispersant, and organic solvent were mixed in the proportions shown in Table 2, 500 parts by mass of zirconia beads having a diameter of 0.3 mm were added, and a paint shaker (manufactured by Asada Tekko) was added. Each pigment dispersion was used for Examples 1-8 and Comparative Examples 1-7.

Production Example 3 Preparation of Binder A Teflon (registered trademark) -covered rotor was placed in a sample bottle and placed in a magnetic stirrer. In this sample bottle, add the binder epoxy resin, polyfunctional epoxy compound, etc. obtained in Production Example 1 in accordance with the formulation shown in Table 2 and dissolve with sufficient stirring at room temperature. A diluent solvent was added to and dissolved by stirring, and this was filtered to obtain binders used in Examples 1 to 8 and Comparative Examples 1 to 7.

Examples 1-8 and Comparative Examples 1-7
According to the formulation shown in Table 2, the pigment dispersions prepared in Production Examples 2 and 3 and the binder were sufficiently mixed to prepare red ink compositions of Examples 1 to 8 and Comparative Examples 1 to 7.
Using the obtained red ink compositions for color filters of Examples 1 to 8 and Comparative Examples 1 to 7, on a glass substrate having a thickness of 0.7 mm (trade name “NA35” manufactured by NH Techno Glass Co., Ltd.) Then, it was applied by spin coating. Thereafter, prebaking was performed on a hot plate at 90 ° C. for 10 minutes.
Thereafter, the substrate was post-baked by heating at 200 ° C. for 30 minutes in a clean oven, and further post-baked by heating at 240 ° C. for 30 minutes to form a red pattern having a thickness of 1.8 μm. The chromaticity x, chromaticity y, transmittance Y (%) and contrast were measured for these 15 types of red patterns. The results are shown in Table 2.

［注］
１）分散剤：商品名［Disperbyk-161」（ビックケミー社製、有機溶剤中に固形分３０質量％）
２）バインダー性エポキシ樹脂：製造例１により得られたもの
３）多官能性エポキシ化合物：商品名「エピコート１５４」（ジャパンエポキシレジン社製）

[note]
1) Dispersant: Trade name [Disperbyk-161] (manufactured by Big Chemie, solid content in organic solvent 30% by mass)
2) Binder epoxy resin: obtained by Production Example 1 3) Polyfunctional epoxy compound: Trade name “Epicoat 154” (manufactured by Japan Epoxy Resin Co., Ltd.)

  As is apparent from Table 2, the red ink compositions of Examples 1 to 8 of the present invention obtained transmittance and contrast equivalent to the red ink compositions of Comparative Examples 1 to 7, and Comparative Examples 1 to 7 The pigment concentration was lower than that of the red ink composition, and the landing position accuracy was greatly improved.

  The red ink composition of the present invention is suitable for forming a film having a predetermined pattern, and is particularly suitably used for forming R (red) pixels in a color filter. The color filter having the red ink composition of the present invention is preferably used for either a color filter used for an image output device such as a liquid crystal display device or a color filter used for an image input device such as a solid-state imaging device. it can. For example, it can also be suitably used as a high-definition color filter used for televisions and the like, particularly as a color filter having a large glass substrate for a liquid crystal display device such as a large television.

Claims (5)

  C. I. Pigment red 242, C.I. I. Pigment red 254, C.I. I. A red ink composition for a color filter, comprising at least two pigments of CI Pigment Red 177 and not containing a yellow pigment.   2. The red ink composition for a color filter according to claim 1, comprising PR242 and having at least one pigment selected from PR254 and PR177.   The red ink composition for a color filter according to claim 1 or 2, wherein the pigment concentration is 45% by mass or less.   The red ink composition for a color filter according to any one of claims 1 to 3, wherein the content of the dispersant in the solid content of the composition is 30% by mass or less.   The color filter formed by the inkjet method using the red ink composition in any one of Claims 1-4.