JP5424591B2 - Black pigment dispersion, its production method and use - Google Patents

Description

  The present invention relates to a black pigment dispersion excellent in pigment dispersibility, and a production method and use thereof. More specifically, the present invention relates to a black pigment dispersion that can form a black film that is stable in dispersibility of the black pigment for a long period of time and is substantially free of aggregates, and a method for producing the black pigment dispersion.

  Titanium oxynitride powder (titanium black) is an inorganic pigment having a high blackness obtained by ammonia reduction of titanium oxide, and is used in a wide range of fields. For example, liquid crystal color filters using its excellent light shielding properties It is used as a black pigment for black matrix (Patent Document 1).

  Titanium black has excellent light-shielding properties, but in recent years, a reduction in the thickness of the black matrix has been demanded, and the content of titanium black in the resin tends to be remarkably increased in order to improve the light-shielding properties. Attempts have also been made to increase the blackness by increasing the reduction degree of titanium black.

  However, when the blending amount of titanium black mixed with the resin is increased, the resin content is relatively decreased, and the stability of the pigment powder (titanium black powder) is lowered. Recently, in order to improve the throughput of the color filter manufacturing process, there is a tendency to use a large amount of a highly volatile low-boiling solvent, and it has become strict to maintain the dispersion stability of the pigment.

On the other hand, titanium black that is not surface-treated has low dispersion stability in the liquid. In particular, when the reduction reaction proceeds, the proportion of active nitride present on the surface increases and the dispersion stability in the liquid further decreases. . For this reason, when a film is formed using a dispersion liquid, even if the dispersion looks good in the liquid, in many cases, foreign matters and aggregates are confirmed during the drying process, making it unusable. Although this agglomerate can be temporarily removed by filtration, reaggregation occurs and long-term use is difficult.
Japanese Patent Laid-Open No. 10-246955

  The present invention solves the above-mentioned conventional problems, the dispersibility of a black pigment made of titanium black powder is stable for a long period of time, and a black pigment dispersion in which aggregates are not substantially generated when a coating film is formed. Provided are liquids, methods for their production and uses.

The present invention relates to a black pigment dispersion in which the above-described problems are solved by the following configuration, a manufacturing method thereof, and an application.
[1] A black pigment powder composed of a titanium oxynitride represented by the general formula TiOxNy (1.0 ≦ x + y ≦ 1.3, 2x <y), a resin, and a solvent, the solvent having an OH group A composite solvent comprising 5% to 50% of a water-soluble solvent as an organic solvent and an ester solvent, and containing a water content of 0.3 to 2.0% with respect to the content of the pigment. Pigment dispersion.
[2] The black pigment dispersion of [1] above, wherein the organic solvent having an OH group is propanol, ethanol, methoxypropanol, or ethoxypropanol.
[3] The black pigment as described in [1] or [2] above, wherein the resin content of the dispersion is 5 to 25% by mass relative to the amount of black pigment, and the amount of the composite solvent of the dispersion is 60 to 90% by mass. Dispersion.
[4] The above-mentioned [1] to the above, containing as a powder component, together with titanium oxynitride, one or more of silica, alumina, zirconia, yttria, calcia, magnesia, titania, iron oxide, manganese oxide, or carbon black [3] The black pigment dispersion described in any one of [3].
[5] A black film forming composition comprising the black pigment dispersion described in any one of [1] to [4].
[6] A black film formed by the composition of [5] above.
[7] A water-soluble solvent which is a black pigment powder composed of a titanium oxynitride represented by the general formula TiOxNy (1.0 ≦ x + y ≦ 1.3, 2x <y), a resin, and an organic solvent having an OH group Formation of a black film that adjusts the water content to 0.3 to 2.0% with respect to the content of the black pigment by adding water during the preparation of the composite solvent consisting of 5% to 50% and ester solvent. A method for producing a composition.

  The dispersion of the present invention is excellent in the dispersion stability of the black pigment (titanium black). Specifically, for example, the dispersion (A) immediately after preparation and the dispersion (B) after 60 days from the preparation. Thus, when each coating film is formed, aggregates are not generated in any coating film, and the average particle diameter of the black pigment powder in the coating film hardly changes. Further, the viscosity of the dispersion liquids (A) and (B) hardly changes.

Hereinafter, the present invention will be specifically described based on embodiments. In addition,% is the mass% except the case intrinsic | native to a unit.
[Black pigment dispersion]
Dispersions of the present invention comprises the general formula TiOxNy (1.0 ≦ x + y ≦ 1.3,2x <y) black pigment powder made of titanium oxynitride represented by the resin, and a solvent, the solvent is OH It is a composite solvent composed of 5% to 50% of a water-soluble solvent which is an organic solvent having a group and an ester solvent, and contains a water content of 0.3 to 2.0% with respect to the content of the pigment. It is a black pigment dispersion characterized.

In general, titanium oxynitride (titanium oxynitride: titanium black) is composed of unreacted raw material titanium dioxide (TiO ₂ ), titanium monoxide (TiO) produced by a reduction reaction, and titanium nitride (TiN produced by a nitriding reaction). ), The ratio of nitrogen is high, and the ratio of titanium nitride (TiN) having a high conductivity increases, so that the resistance value decreases.

Conventional titanium oxynitrides have a high proportion of low-conductivity titanium oxide (TiO ₂ , TiO), and in general formula TiOxNy, the amount of nitrogen y is less than twice the amount of oxygen x (2x> y), The resistance value of the body increases and the blackness decreases.

  On the other hand, the titanium oxynitride used in the present invention has a high nitrogen content. In the general formula TiOxNy, the ratio of nitrogen to oxygen is 2x <y, and the total amount of oxygen and nitrogen (x + y) is 1.0. ≦ x + y ≦ 1.3. Therefore, the titanium oxynitride used in the present invention has low powder resistance and high blackness (L value).

  As the titanium oxynitride, one containing 0.005 to 2.0% of phosphorus (P) and / or silicon (Si) can be used. By containing phosphorus and / or silicon in the above content, the active reactivity of titanium nitride is suppressed, and even if the amount of titanium nitride is large, it has good dispersibility and excellent long-term dispersion stability. .

  Titanium oxynitride powder containing phosphorus and / or silicon is obtained by subjecting titanium oxide powder to nitridation reduction treatment and represented by the general formula TiOxNy (1.0 ≦ x + y ≦ 1.3, 2x <y) When producing black conductive powder consisting of powder, oxide, nitride, inorganic acid, ammonia salt, phosphorus salt of alkali salt and / or silicon compound is added to raw material titanium oxide powder for nitriding It can be obtained by reduction treatment.

  The black pigment dispersion of the present invention includes, as a powder component, together with titanium oxynitride, an oxide such as silica, alumina, zirconia, yttria, calcia, magnesia, titania, iron oxide, manganese oxide, or black pigment such as carbon black. 1 type, or 2 or more types can be included.

  By containing the above oxide together with the titanium oxynitride, the stability of the dispersion can be improved, and further, the insulating properties, adhesion, and surface roughness of the coating film can be improved. Moreover, blackness can be raised by including black pigments, such as carbon black. The content of the oxide and carbon black is suitably 15% or less with respect to the titanium oxynitride.

  The black pigment dispersion of the present invention contains a dispersion resin and a solvent together with the titanium oxynitride powder. As the resin, those having an adsorbing group that adsorbs to the pigment surface such as an amino group, an amide group, or a carboxyl group are effective, and a commercially available dispersant can be used. Specific examples include polyester, polyurethane, epoxy, silicone, and acrylic. Moreover, these can also be used in mixture of 2 or more types. Moreover, surfactants such as cationic, anionic, nonionic, amphoteric, silicone, and fluorine can be used alone or in combination.

  The resin content of the dispersion is preferably from 5 to 25%, more preferably from 10% to 20%, based on the amount of black pigment (titanium oxynitride). If the resin content is less than 5%, adsorption to the pigment surface is insufficient and a stable dispersion cannot be obtained. On the other hand, if the resin content is more than 25%, the reaction between the resins tends to occur and the viscosity becomes high, and a stable dispersion state cannot be obtained.

The solvent used in the black pigment dispersion of the present invention is a composite solvent composed of an organic solvent having an OH group of 5% to 50% and an ester solvent. By using a composite solvent containing an organic solvent having an OH group and an ester solvent, the stability of the dispersion can be obtained, and the coating property, drying property, thin film density, surface smoothness, and adhesion during thin film formation can be obtained. Property is improved.

Examples of the organic solvent having an OH group include alcohols such as ethanol and propanol, ethers such as glycol ether, glycols such as ethylene glycol and propylene glycol, cellosolves such as methyl cellosolve and ethyl cellosolve, and the like. Can do.

  Examples of ester solvents that can be used include acetate esters such as butyl acetate and propyl acetate, and glycol ether esters such as propylene glycol monomethyl ether acetate (PMA). These acetate esters and glycol ether esters are used as solvents for black ink liquids, coating films that form black matrices, and the like. In addition to acetic acid esters and glycol ether esters, propionic acid esters, lactic acid esters, cellosolve acetates, ketones, hydrocarbon solvents, benzene solvents and the like can be used. These can be used alone or in combination of two or more, and ketones, hydrocarbon solvents, and benzene solvents may be partially substituted.

The amount of the organic solvent having an OH group in the composite solvent is preferably 5 to 50%. When the amount of the organic solvent having an OH group is less than 5%, the above effect using the composite solvent becomes poor. On the other hand, when the content of the organic solvent having an OH group is more than 10%, the drying property is deteriorated, and it becomes difficult to obtain a dense thin film excellent in surface smoothness.

  The composite solvent preferably has a boiling point of 140 ° C. or lower. When the boiling point is 140 ° C. or higher, the drying rate is slow, so that a dense film cannot be obtained, and the productivity is remarkably lowered, resulting in an increase in cost. Further, the amount of the composite solvent in the dispersion is preferably 60 to 90%. If it is less than 60%, the viscosity is too high for the dispersion liquid to be difficult to handle, and if it is more than 90%, the pigment ratio is too low to obtain a film having the desired film thickness.

  The black pigment dispersion of the present invention contains 0.3 to 2.0% of water with respect to the amount of black pigment (titanium oxynitride). By including the water content in this range, the dispersion stability of the black pigment is remarkably improved, and aggregates are greatly reduced when a film is formed. If the water content is less than 0.3%, the aggregation of the pigment cannot be sufficiently suppressed, and aggregates are formed in the film formed after storage of the liquid, and the viscosity is reduced during the storage period of the liquid. The storage stability of the dispersion is low. On the other hand, if the water content exceeds 2.0%, the aggregation of the pigment is suppressed, but the resin is hydrolyzed and the viscosity of the dispersion becomes gradually higher.

〔Production method〕
The black pigment dispersion of the present invention is prepared by preparing a black pigment powder composed of the above titanium oxynitride, a resin, and the above composite solvent, adding water at the time of preparation, and adding 0.3 to the content of the black pigment. It can be manufactured by adjusting the water content to 2.0%. Specifically, the amount of water contained in the black pigment and the solvent is measured in advance, and the insufficient amount of water may be added during preparation.

[Black film]
The black pigment dispersion of the present invention is suitable as a coating liquid for forming a black film such as a black matrix. The coating film formed using the black pigment dispersion of the present invention has almost no foreign matter (such as pigment aggregates), and a high-quality black film in which the pigment is uniformly dispersed can be obtained.

  Examples of the present invention are shown below together with comparative examples. The average particle size of the pigment in the dispersion was measured using a Coulter measuring device (N4plus). The presence or absence of aggregates during film formation was determined by visual observation using 100-fold optical microscope observation. The viscosity of the dispersion was measured with an E-type viscometer (manufactured by Tokimec). The results of the examples are shown in Table 1, and the results of the comparative examples are shown in Table 2.

[Example 1]
100 parts by weight of titanium black powder (TiO _0.24 N _0.92 ), 10 parts by weight of a commercially available basic dispersion resin, and 390 parts by weight of a mixed solvent (butyl acetate: isopropanol = 8: 2) were prepared. At this time, the amount of water contained in the titanium black was 0.3%, and the amount of water contained in the mixed solvent was 0.01%. Therefore, the water content of the dispersion was adjusted to 0.7% with respect to the amount of titanium black. Water was added. The prepared dispersion was dispersed with a circulating sand mill, and diluted by adding the above composite solvent so that the final pigment concentration was 25%.
The prepared dispersion was filtered through a 1 micron filter, and then a spin coat film was formed on a glass substrate. This film formation was observed with a 100 × optical microscope to examine the presence or absence of foreign matter. As a result, the film formation was uniform with no foreign matter present. The average particle size of titanium black dispersed in the liquid was 120 nm.
The dispersion was stored at 25 ° C. for 60 days, and then spin-coated on a glass substrate without filtration. This film was a uniform film with no foreign matter present. The average particle size of titanium black dispersed in the liquid was 120 nm.

[Examples 2 to 9]
A black pigment dispersion was prepared in the same manner as in Example 1. Table 1 shows the pigment, solvent, resin, and amount of water used. A black film was formed using this dispersion. The results are shown in Table 1.

  As shown in Table 1, the dispersions of Examples 1 to 9 showed no dispersibility in the formed film using the dispersion immediately after preparation, and showed good dispersibility of the pigment. Also, when looking at the dispersion after 60 days, the average particle diameter of the titanium black dispersed in the liquid, the viscosity of the liquid is almost the same as the dispersion immediately after the preparation, no foreign matter is observed in the film formation, The dispersion is kept stable throughout the storage period of the liquid.

[Comparative Examples 1-4]
According to the conditions shown in Table 2, a black pigment dispersion was prepared in the same manner as in Example 1, and a black film was formed using this dispersion. The results are shown in Table 2.

  In all of the dispersions of Comparative Examples 1 to 4, the viscosity of the liquid was significantly increased after 60 days had elapsed, and, except for Comparative Example 2, foreign matter was observed during film formation using the dispersion after 60 days. It was done.

Claims (7)

A black pigment powder composed of a titanium oxynitride represented by the general formula TiOxNy (1.0 ≦ x + y ≦ 1.3, 2x <y), a resin, and a solvent, and the solvent is an organic solvent having an OH group. A black pigment dispersion characterized in that it is a composite solvent comprising 5% to 50% of a certain water-soluble solvent and an ester solvent, and contains a water content of 0.3 to 2.0% with respect to the content of the pigment. . The black pigment dispersion according to claim 1, wherein the organic solvent having an OH group is propanol, ethanol, methoxypropanol, or ethoxypropanol. The black pigment dispersion according to claim 1 or 2, wherein the resin content of the dispersion is 5 to 25% by mass with respect to the amount of black pigment, and the amount of the composite solvent of the dispersion is 60 to 90% by mass. Any one of Claims 1-3 which contains 1 type, or 2 or more types of a silica, an alumina, a zirconia, a yttria, a calcia, a magnesia, a titania, an iron oxide, a manganese oxide, or carbon black as a powder part. A black pigment dispersion described in the above. The composition for black film formation which consists of a black pigment dispersion liquid in any one of Claims 1-4. A black film formed by the composition of claim 5. Black pigment powder made of titanium oxynitride represented by the general formula TiOxNy (1.0 ≦ x + y ≦ 1.3, 2x <y), a resin, and a water-soluble solvent 5% which is an organic solvent having an OH group A composition for forming a black film, which is adjusted to have a moisture content of 0.3 to 2.0% with respect to the content of the black pigment by adding moisture at the time of preparing a composite solvent comprising 50% and an ester solvent. Manufacturing method.