JP4614694B2 - Compositions and methods for surface treatment of pigments - Google Patents

Description

  The present invention relates to a pigment composition, and more particularly to a surface-treated pigment composition, a surface-treated pigment dispersion and a method for treating pigment particles.

  It is known in the art to surface treat pigment particles to improve the dispersion properties of pigment particles in liquids such as binder resins or polymer solutions. There are methods of treating the surface of pigment particles by using a high molecular weight polymer to form a coating on the surface of the pigment particles. Examples of high molecular weight polymer dispersants are disclosed in US Pat. Generally, high molecular weight polymers are attached to the surface of pigment particles by adsorption.

  Patent Document 2 discloses a pigment-dispersed resin having a weight average molecular weight in the range of 5,000 to 100,000 obtained by copolymerizing a macromonomer and an ethylenically unsaturated monomer. The production of the macromonomer is necessary to produce such a high molecular weight polymer dispersed resin. This patent document discloses an epoxy-containing polymerizable unsaturated monomer (eg, glycidyl methacrylate) for use in making macromonomers.

  US Pat. No. 6,057,049 describes a colored coating composition comprising (a) a polymer having carboxyl and carboxylate groups, (b) a polymer having hydroxyl and epoxy groups, (c) a pigment-dispersant and (d) a pigment. We are disclosing things. The polymer (b) disclosed therein is produced by copolymerizing an epoxy group-containing ethylenically unsaturated monomer with a hydroxyl group-containing ethylenically unsaturated monomer and other copolymerizable ethylenically unsaturated monomers. High molecular weight copolymer.

  A surface treatment agent containing silicon (for example, a silylating agent or a silane coupling agent) is generally bonded to the surface of the pigment particle through a chemical bond. For example, Patent Document 4 discloses a method of treating an organic pigment with a silylating agent or a silane coupling agent. An example of a silylating agent disclosed therein is glycidoxypropyltrimethoxysilane containing an epoxy group.

  In US Pat. No. 6,057,059, a dispersion of pigment particles is brought into contact with halosilane or organohalosilane, the temperature is increased to form siloxane on the surface of the particles, and the surface-treated particles are pressed. Disclosed is a method for treating pigment particles by recovering as cake or dry particles.

  Patent Document 6 discloses an inorganic particulate material whose surface is modified with a silane coupling agent having at least one functional group selected from the group consisting of a vinyl group, a methacryloyl group, an epoxy group, and an amino group; and the silane Disclosed is an aqueous coating composition comprising a water-dispersible resin having a functional group that is reactive with a functional group of a coupling agent. In the example of this patent document, glycidoxypropyl-trimethoxysilane is used as a silane coupling agent having an epoxy group.

  Silicon-containing surface treatments (eg, alkoxysilanes) provide the treated pigment with improved physical properties (eg, high heat and chemical resistance, good dispersibility, good weather resistance, etc.). However, the physical properties of the film obtained from the dispersion of such treated pigment particles are insufficient due to the poor compatibility of the treated particles with the binder resin due to the presence of silicon. .

Conventionally, color filters for flat displays include a colored layer formed from a composition containing a pigment dispersed in a binder. Pigment composition with excellent pigment dispersion characteristics, small pigment particle size, high dispersion stability, and good compatibility between the components contained in the composition to provide good light transmittance characteristics for color filters It is desirable to provide goods.
JP-A-5-320533 US Pat. No. 6,548,174 US Pat. No. 5,969,048 JP 7-331102 A US Pat. No. 6,120,596 US Pat. No. 5,719,206

  One object of the present invention is to treat pigment particles with a compound that does not contain silicon, resulting in improved compatibility of the pigment particles with the components (especially the binder resin in the color resist). And providing a pigment composition that can be enhanced and film properties (eg, transparency) can be enhanced.

  Another object of the present invention is to treat pigment particles by using a low molecular weight silicon-free compound instead of a high molecular weight polymer to treat the pigment particles to form a thin layer on the pigment surface. Providing a method, thereby producing a pigment composition that can be dispersed with a dispersant to a small particle size and exhibit excellent flow properties, especially low viscosity and low Ti (thixotropic index) It becomes possible to do. Furthermore, in the present invention, the amount of dispersant required to disperse the pigment can be reduced, so that the heat resistance (expressed as ΔEab) of the film obtained from the pigment composition can be enhanced.

  According to one aspect of the present invention, a pigment composition includes pigment particles and an epoxy compound for surface treating the pigment particles, the epoxy compound having the general formula:

［式中、Ｒ¹、Ｒ²、Ｒ³、Ｒ⁴およびＲ⁵は、それぞれ、独立して、水素、または置換もしくは非置換のアルキルであり、あるいは、Ｒ²およびＲ⁴は一緒になって５〜７員環を形成し得、そして
Ｒ⁶は、水素、−ＯＯＣＲ⁷、−ＯＲ⁸、−ＯＯＣ−ＣＲ⁹＝ＣＲ¹⁰Ｒ¹¹；ジフェニル、フェニル、または置換もしくは非置換のアルキルもしくはシクロアルキルを含有するモノエポキシまたはポリエポキシ基；あるいはポリエーテル基を含有するモノエポキシまたはポリエポキシ基であり、
Ｒ⁷、Ｒ⁸、Ｒ¹⁰およびＲ¹¹は、それぞれ、独立して、水素、置換もしくは非置換のアルキル、置換もしくは非置換のシクロアルキル、置換もしくは非置換のアリール、または置換もしくは非置換のアルケニルであり、
Ｒ⁹は、水素、またはアルキルであり、
但し、該エポキシ化合物はケイ素含有基を有さない］
を有する。

[Wherein R ¹ , R ² , R ³ , R ⁴ and R ⁵ are each independently hydrogen, or substituted or unsubstituted alkyl, or R ² and R ⁴ are taken together. A 5- to 7-membered ring can be formed and R ⁶ is hydrogen, —OOCR ⁷ , —OR ⁸ , —OOC—CR ⁹ ═CR ¹⁰ R ¹¹ ; diphenyl, phenyl, or substituted or unsubstituted alkyl or cycloalkyl A monoepoxy or polyepoxy group containing: a monoepoxy or polyepoxy group containing a polyether group,
R ⁷ , R ⁸ , R ¹⁰ and R ¹¹ are each independently hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted aryl, or substituted or unsubstituted alkenyl. And
R ⁹ is hydrogen or alkyl;
However, the epoxy compound has no silicon-containing group]
Have

  According to another aspect of the invention, a pigment dispersion includes a dispersant and pigment particles dispersed in the dispersant, wherein the pigment particles have the general formula (I) It is treated with an epoxy compound.

According to a further aspect of the present invention, a method for surface treatment of pigment particles includes the following:
Mixing the pigment particles and the epoxy compound in the presence of a solvent to form a slurry; and reacting the pigment particles and the epoxy compound at elevated temperature (20 ° C. to the boiling point of the solvent). [Wherein the epoxy compound has the general formula (I)].
The method can further include the step of removing the solvent from the slurry, thereby drying the surface treated pigment particles.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention, low molecular weight epoxy compound is used to react with the surface of the pigment particles. The epoxy compounds used in the present invention are mainly commercially available organic compounds mainly having a molecular structure having an epoxy equivalent weight of less than 1000. When pigment particles are treated with low molecular weight epoxy compounds at high temperatures, they react with the epoxy compounds and a coating layer is formed on the surface of the pigment particles via physical and / or chemical bonds. .

  Low molecular weight epoxy compounds suitable for treating pigment particles according to the present invention may include conventional epoxy compounds having an epoxy equivalent weight of less than 1000, alone or in combination. Preferred compounds are monoglycidyl or polyglycidyl ethers and monoglycidyl or polyglycidyl esters. In detail, epoxy compounds suitable for the present invention may include the following: monoepoxy compounds such as aliphatic glycidyl esters, alicyclic glycidyl esters, aromatic glycidyl esters, aliphatic glycidyl ethers, fats Cyclic glycidyl ethers, aromatic glycidyl ethers, aliphatic, alicyclic or aromatic glycidyl acrylates, or other suitable monoepoxy compounds; and commonly used as epoxy resins and substituted or unsubstituted alkyl or Diepoxy or polyepoxy compounds, and other suitable polyepoxy compounds containing cycloalkyl, aliphatic groups, monophenolic groups, diphenolic groups, or polyether groups.

  Examples of the aforementioned epoxy compounds are ethers such as 2-ethylhexyl glycidyl ether, butyl glycidyl ether, decyl glycidyl ether, phenyl glycidyl ether, cresyl glycidyl ether, p-tertbutylphenyl glycidyl ether, 1,4-butanediol diester. Glycidyl ether, neopentyl glycol diglycidyl ether, trimethylolpropane triglycidyl ether, bis-2,3-epoxycyclopentyl glycidyl ether, 1,4-bis (hydroxymethyl) cyclohexane diglycidyl ether, and monophenolic or diphenolic Monoglycidyl or polyglycidyl ethers such as compounds, glycidyl phenolic epoxy resins, alicyclic epoxy compounds (eg, Lohexene oxide and cyclopentene oxide), esters such as glycidyl ethanolate, glycidyl propanoate, glycidyl butyrate, glycidyl valerate, glycidyl decanoate, glycidyl undecanoate, glycidyl decanoate, 3,4- Epoxycyclohexylmethyl-3 ′, 4′-epoxy-4-cyclohexylcarboxylate, diglycidyl 1,2-cyclohexanedicarboxylate and the like, as well as other epoxy compounds such as triglycidyl isocyanurate, glycidyl methacrylate, 3,4-epoxycyclohexyl (Meth) acrylates and other acrylate monomers containing epoxy groups.

  Pigments that can be surface treated according to the present invention can be organic or inorganic pigments. The present invention is particularly suitable for pigments used in the production of color filters. Examples of pigments include pigment blue (PB15: 6), pigment red PR254 (diketopyrrolo pyrrole), pigment yellow PY138 (quinophthalone), pigment yellow PY139 (isoindolinone), pigment green PG36 ( Phthalocyanine copper), silica, fumed silica and the like.

  In the present invention, the solvent for dispersing the pigment used in the process of treating the pigment with an epoxy compound can be any known solvent that is commonly used for dispersing pigment particles. Examples of such solvents include toluene, xylene, cyclohexanone, and propylene glycol monomethyl ether acetate (PMA).

  The following examples are provided for the purpose of illustrating the invention and should not be construed as limiting the scope of the invention in any way, the scope of the invention being claimed. It is prescribed by.

Example (1)
12.0 parts by weight of pigment blue (PB15: 6) was mixed with 80.8 parts by weight of solvent (toluene) in a mixer. After 2 hours of mixing, 7.2 parts by weight of 2-ethylhexyl glycidyl ether (2-EHGE) was slowly added to the mixer until it was completely dispersed. Silica-zirconia beads having dimensions of about 0.3-0.4 mm were then added to the mixer and ground until the resulting mixture had a particle size of about 90 nm. The obtained slurry was heated to the reflux temperature and reacted. After 4 hours, the solvent was removed under vacuum in a Rotavapor for drying, and the dried residue was ground to form a powder.

Example (2)
Using a stirrer, 6.0 parts by weight of butyl glycidyl ether (BGE), 15.0 parts by weight of pigmentgreen (PG36), and 79 parts by weight of xylene (solvent) until the pigment is completely dispersed. For 2 hours. The mixture was then milled to a particle size of 130 nm using silica-zirconia beads having a diameter of about 0.3-0.4 mm. The resulting slurry was heated to 90 ° C., allowed to react for 8 hours, and then dried in a Rotavapor under vacuum to concentrate the slurry. Finally, the slurry was dried and ground to form a powder.

Example (3)
1.5 parts by weight glycidyl aliphatic ester, 10 parts by weight pigment BTCF (PR254) and 88.5 parts by weight toluene were mixed in a mixer for 2 hours until the pigment was completely dispersed. The mixture was then ground to a particle size of about 150 nm using silica-zirconia beads having a diameter of about 0.3-0.4 mm. After reacting at a temperature of 90 ° C. for 6 hours, followed by drying under vacuum in a Rotavapor, the solvent was removed and the dried residue was ground into a powdered form.

Example (4)
20 parts by weight of pigment 2RCF (PY139), 65.5 parts by weight of toluene, and 10 parts by weight of propylene glycol monomethyl ether acetate (PMA) were mixed in a mixer until the pigment was completely dispersed. The mixture was then ground to the desired particle size and 4.5 parts by weight of decyl glycidyl ether (DGE) was gradually added thereto. The resulting mixture was heated and allowed to react at a temperature of about 90 ° C. for 6 hours, after which the pressure was reduced to 20 mmHg by Rotavapor. The concentrated and dried residue was ground to a powdered form.

Example (5)
12 parts by weight pigment yellow (PY138), 65 parts by weight toluene, 20 parts by weight cyclohexanone are mixed in a mixer for 2 hours, and then silica-zirconia beads having a diameter of about 0.3-0.4 mm are mixed. Used to mill to provide a particle size of about 130 nm. To the mixture, 3 parts by weight of glycidyl methyl methacrylate (GMA) was added. After reaction for 6 hours at a temperature of 90 ° C., the pressure was subsequently reduced to 20 mmHg by Rotavapor and the concentrated and dried residue was ground to a powder.

Example (6)
20 parts by weight of the powder prepared in each of Examples 1-5 was mixed with 9.0 parts by weight of a dispersant (Disperbyk 163 from Byk-Chemie) and 71 parts by weight of propylene glycol monomethyl ether acetate (PMA), followed by And then pulverized to form a dispersion. Table 1 shows the viscosity value, average particle size, and Ti value (thixotropic index) of the obtained dispersions of the powders produced in Examples 1 to 5.

Comparative Examples 1-5
Comparative Examples 1-5 were performed in the same manner as Examples 1-6 except that the epoxy compounds used to treat the pigments in Examples 1-5 were omitted in the comparative examples. Table 2 shows the viscosity value, average particle size, and Ti value (thixotropic index) of the dispersions of Comparative Examples 1 to 5.

表（１）および（２）は、比較例１〜５と比較して、本発明に従う実施例１〜５は、より低い粘度値およびより小さい粒度を示すことを表わす。高温（５０℃）で７日間以上保存後、実施例１〜５の粘度および粒度の変化は、比較例１〜５のそれと比較して小さいことが観察された。このことは、実施例１〜５の保存安定性は、比較例１〜５のそれよりも良好であることを示す。表（１）における実施例１〜５のＴｉ値（チキソトロピックインデックス）は、表（２）に示されるＴｉ値よりも低く、そしてニュートン（Newtonion）レオロジーのそれに近い。このことは、実施例１〜５のディスパージョンが良好な流動特性を有することを示す。

Tables (1) and (2) show that Examples 1-5 according to the present invention show lower viscosity values and smaller particle sizes compared to Comparative Examples 1-5. After storage for 7 days or more at high temperature (50 ° C.), it was observed that the changes in viscosity and particle size of Examples 1-5 were small compared to those of Comparative Examples 1-5. This indicates that the storage stability of Examples 1 to 5 is better than that of Comparative Examples 1 to 5. The Ti values (thixotropic indexes) of Examples 1-5 in Table (1) are lower than the Ti values shown in Table (2) and are close to that of Newtonion rheology. This indicates that the dispersions of Examples 1 to 5 have good flow characteristics.

Examples 7 and 8
According to the procedure of Example 6, pigment dispersions containing 20% and 30% dispersant (Disperbyk 163) were made using pigment green surface treated in Example 2. Table 3 shows the viscosity, average particle size, and chromaticity level of the resulting pigment dispersion.

Comparative Examples 7, 8 and 9
According to the procedure of Example 6, pigment dispersions containing 20%, 30% and 50% dispersant (Disperbyk 163) were made using non-surface treated pigment green. Table 3 shows the viscosity, average particle size, and chromaticity level of the resulting pigment dispersion.

表３は、比較例７および８はそれぞれ実施例７および８と同量の分散剤を含有しているが、それらは、実施例７および８と比較してより高い粘度およびより大きな平均粒度を有することを示している。実施例８と比較例９との比較により、処理されていない顔料は、実施例８のそれに近いレベルまで粘度および平均粒度を低下させるためには、より多くの量の分散剤（５０％まで）を必要とすることが理解され得る。このことは、顔料を分散させるために必要とされる分散剤の量は、顔料を本発明に従って表面処理した後、減少されることを示している。

Table 3 shows that Comparative Examples 7 and 8 contain the same amount of dispersant as Examples 7 and 8, respectively, but they have higher viscosity and higher average particle size compared to Examples 7 and 8. It shows that it has. A comparison of Example 8 and Comparative Example 9 shows that untreated pigment has a higher amount of dispersant (up to 50%) to reduce viscosity and average particle size to levels close to that of Example 8. Can be understood to require. This indicates that the amount of dispersant required to disperse the pigment is reduced after the pigment is surface treated according to the present invention.

  The heat resistance of each of Examples 7 and 8 and Comparative Examples 7, 8 and 9 is represented by a color difference (ΔEab), which is a colorimeter (MCPD manufactured by Otsuka Electronic Co., Ltd.). ) Was used to test the color change of each dispersion before and after heating. The smaller the ΔEab value, the higher the heat resistance. Table (3) shows that the heat resistance of Example 7 or 8 (ΔEab = 0.8) is higher than that of Comparative Examples 7, 8 and 9. This also shows that the thermal stability of Example 7 or 8 is better than that of Comparative Examples 7, 8 and 9.

  The suitability of each of Examples 7 and 8 and Comparative Examples 7, 8 and 9 is indicated by the values of Y, x, y, which were also measured using a colorimeter (MCPD). The higher the Y value, the higher the light transmittance. When the light transmittance is high, the compatibility of the components in the dispersion is good. Table (3) shows that the surface treated pigment used in Examples 7 and 8 is better for the dispersant compared to the unsurfaced pigment used in Comparative Examples 7, 8 and 9. It shows that it is compatible.

Claims (10)

A pigment comprising surface-treated organic pigment particles suitable for forming a light transmissive pigment layer of a color filter,
The individual powders of the surface-treated organic pigment particles are obtained by heating in the presence of a pigment dispersing solvent to react with the epoxy compound and drying the solvent,
The epoxy compound has the general formula:

Wherein R ¹ , R ² , R ³ , R ⁴ and R ⁵ are each independently hydrogen or unsubstituted alkyl, or R ² and R ⁴ together are Can form a 7-membered ring and R ⁶ is hydrogen, —OOCR ⁷ , —OR ⁸ , —OOC—CR ⁹ = CR ¹⁰ R ¹¹ ,
R ⁷ , R ⁸ , R ¹⁰ and R ¹¹ are each independently hydrogen, unsubstituted alkyl, unsubstituted aryl, or unsubstituted alkenyl,
R ⁹ is hydrogen or alkyl.
A pigment having The pigment of claim 1, wherein the epoxy compound has an epoxy equivalent weight of less than 1000. The pigment according to claim 1 or 2, wherein the epoxy compound is selected from the group consisting of glycidyl ethers, glycidyl esters, and alicyclic epoxy compounds. The pigment according to claim 1, wherein the epoxy compound is selected from the group consisting of glycidyl methacrylate and glycidyl acrylate. A method of preparing a pigment containing surface-treated organic pigment particles, comprising:
Mixing the organic pigment particles and the epoxy compound in the presence of a solvent to form a slurry;
Heating the slurry to react the organic pigment particles with the epoxy compound; and removing the solvent from the slurry, thereby drying the surface treated organic pigment particles;
Including
Here, the epoxy compound has the general formula:

Wherein R ¹ , R ² , R ³ , R ⁴ and R ⁵ are each independently hydrogen or unsubstituted alkyl, or R ² and R ⁴ together are Can form a 7-membered ring and R ⁶ is hydrogen, —OOCR ⁷ , —OR ⁸ , —OOC—CR ⁹ = CR ¹⁰ R ¹¹ ,
R ⁷ , R ⁸ , R ¹⁰ and R ¹¹ are each independently hydrogen, unsubstituted alkyl, unsubstituted aryl, or unsubstituted alkenyl,
R ⁹ is hydrogen or alkyl.
Having a method. The method of claim 5 , wherein the epoxy compound has an epoxy equivalent weight of less than 1000. The method according to claim 5 or 6 , wherein the epoxy compound is selected from the group consisting of glycidyl ethers, glycidyl esters and alicyclic epoxy compounds. The method according to claim 5 , wherein the epoxy compound is selected from the group consisting of glycidyl methacrylate and glycidyl acrylate. The method according to claim 5 , further comprising the step of removing the solvent and drying the organic pigment particles treated with the epoxy compound. The pigment obtained by the method in any one of Claims 5-9 .