JP2017052847A - Black pigment dispersion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a black pigment dispersion having very high dispersion stability of black iron oxide.SOLUTION: This invention relates to a black pigment dispersion comprising black iron oxide, hydrophobic carbon black, and aqueous solvent. The black iron oxide preferably has a solid content of 70 wt.% or less. The black pigment dispersion preferably also comprises dispersant.SELECTED DRAWING: None

Description

The present invention relates to a black pigment dispersion containing magnetic iron oxide.

As the black pigment, carbon black, black iron oxide, titanium black and the like are generally used. These black pigments are dispersed in an aqueous medium and used for applications such as paints. Among these black pigments, carbon black and titanium black have high stability in an aqueous medium and are used in various applications.

On the other hand, black iron oxide has magnetism, easily aggregates, is difficult to disperse, and even if it can be dispersed on a scale, it is very poor in stability. Therefore, the use as an aqueous dispersion has been greatly restricted. Patent Document 1 discloses a dispersion liquid obtained by blending various pigments such as black iron oxide, red bean paste, koji, yellow iron oxide, and blending poly-γ-L-glutamic acid to improve dispersion stability. However, the dispersion stability of black iron oxide was not always sufficient.

JP 2012-1503 A

An object of the present invention is to provide a black pigment dispersion in which the dispersion stability of black iron oxide is very high.

The present inventors have investigated the dispersion stability of black iron oxide. When hydrophobic carbon black is used in combination with black iron oxide, the dispersion stability of black iron oxide, which tends to aggregate due to its magnetic property, is remarkably improved. The present invention has been completed.

That is, the present invention relates to a black pigment dispersion containing black iron oxide, hydrophobic carbon black, and an aqueous solvent.

The solid content of black iron oxide is preferably 70% by weight or less.

Furthermore, it is preferable to contain a dispersing agent.

Since the black pigment dispersion of the present invention contains hydrophobic carbon black, the dispersion stability of black iron oxide, which is a black pigment, can be remarkably improved. Specifically, even if precipitation occurs after several months, it can be redispersed by lightly stirring.

The SEM photograph of the black iron oxide used in the Example. The SEM photograph of carbon black used in the example. The SEM photograph of the black pigment produced in the Example.

The black pigment dispersion of the present invention is characterized by containing black iron oxide, hydrophobic carbon black, and an aqueous solvent.

Black iron oxide (magnetite) is iron oxide having magnetism, and is a component of black rust and magnetite represented by the chemical formula of Fe ₃ O ₄ . The primary particle diameter of black iron oxide is not particularly limited, but is preferably 10 to 400 nm, and more preferably 100 to 300 nm. If it exceeds 400 nm, the color stability when used as a coloring material is lowered, and if it is less than 10 nm, color absorption tends to be poor and black tends to be weakened.

The black iron oxide content in the black pigment dispersion is preferably 70% by weight or less, more preferably 50% by weight or less, and further preferably 20% by weight or less. When it exceeds 70% by weight, it becomes difficult to perform dispersion treatment due to thickening due to high concentration. On the other hand, the lower limit is not particularly limited, but is preferably 0.01% by weight or more, and more preferably 1% by weight or more.

Although the primary particle diameter of hydrophobic carbon black is not specifically limited, 10-400 nm is preferable and 80-150 nm is more preferable. If it exceeds 400 nm, it becomes impossible to cover the black iron oxide, and if it is less than 10 nm, the film thickness covering the black iron oxide tends to be too thin to prevent aggregation. The pH is also not particularly limited, and is preferably 3-8.

The content of the hydrophobic carbon black is preferably 15% by weight or less, more preferably 10% by weight or less in the black pigment dispersion. If it exceeds 15% by weight, it tends to be difficult to perform dispersion treatment due to thickening due to high concentration. On the other hand, the lower limit is not particularly limited, but is preferably 0.1% by weight or more.

The ratio of black iron oxide to hydrophobic carbon black is not particularly limited, but the content of black iron oxide is preferably 60 to 90% by weight and preferably 70 to 85% by weight in 100% by weight of both components. If it exceeds 90% by weight, the carbon cannot cover the black iron oxide, causing aggregation and sedimentation. If it is less than 60% by weight, the excess carbon tends to cause poor dispersion.

The particle diameter ratio between black iron oxide and hydrophobic carbon black is not particularly limited, but when the particle diameter of black iron oxide is 1, 0.15 to 0.5 is preferable, and 0.25 to 0.45 is more preferable. . If it exceeds 0.5, the black iron oxide cannot be covered, and if it is less than 0.15, the film thickness covering the black iron oxide tends to be thin and aggregation cannot be prevented.

The aqueous solvent is water or an organic solvent soluble in water. Examples of water-soluble organic solvents include alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol; ethylene glycol, propylene glycol, butylene Glycols such as glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol methyl ether, diethylene glycol ethyl ether, triethylene Glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobuty Glycol ethers such as ether, polyhydric alcohols such as glycerin, N- methyl-2-pyrrolidone, 2-pyrrolidone, and nitrogen-containing compounds such as 1,3-dimethyl-2-imidazolidinone. The content of the aqueous solvent is not particularly limited, and it may be blended so that the solid content concentration is preferably 70% by weight or less, more preferably 50% by weight or less. If it exceeds 70% by weight, it tends to be difficult to perform dispersion treatment due to thickening due to high concentration. On the other hand, the lower limit is not particularly limited but is preferably 1% by weight or more.

It is preferable to add a dispersant to the black pigment dispersion of the present invention. The dispersant is not particularly limited, and examples thereof include a surfactant and a dispersion stabilizer due to thickening. For example, homopolymers or copolymers using one or more compounds selected from acrylic acid, methacrylic acid or alkyl esters thereof as raw material monomers, acrylic acid, methacrylic acid or alkyl esters thereof. A copolymer of one or more kinds and octylacrylamide is used. Examples of the anionic dispersant are selected from polyaspartic acid, polyglutamic acid, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-α-methylstyrene-acrylic acid copolymer, and salts thereof. One or two or more types, that is, as the anionic dispersant, polyaspartic acid, polyglutamic acid, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, and styrene-α-methylstyrene-acrylic acid copolymer And those containing at least one of these, or one or more of these salts.

The black pigment dispersion of the present invention can be blended with optional components such as a viscosity modifier, a coating film forming component, an adhesive component, an antifoaming agent, and an antiseptic, as long as the dispersion stability of black iron oxide is not impaired. .

In the black pigment dispersion of the present invention, the dispersion average particle diameter of the black pigment composed of black iron oxide and carbon black is preferably 100 to 400 nm, and more preferably 200 to 300 nm. The median diameter is preferably 100 to 400 nm, and more preferably 200 to 300 nm.

Although the manufacturing method of the black pigment dispersion of this invention is not specifically limited, For example, after mix | blending each component, it can manufacture by disperse | distributing black iron oxide with a well-known dispersing apparatus. Examples of the dispersing device include a media mill such as a ball mill, a sand mill, and a roll mill, a homomixer, and an attritor. When glass beads are used, the blending amount of the glass beads is not particularly limited, but is preferably 80 to 100 parts by weight with respect to 100 parts by weight of black iron oxide.

Since the black pigment dispersion of the present invention is excellent in dispersion stability, it can be applied to various uses such as cosmetics, inkjet inks, water-based inks and water-based paints.

EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited to these Examples.

Example 1
Black iron oxide (BL-100P, average primary particle diameter 250 nm, manufactured by Titanium Industry Co., Ltd.) 5.1 parts, hydrophobic carbon black (Sun Chroma, average primary particle diameter 100 nm, manufactured by Sun Chemical Co., Ltd.) 0.9 parts, dispersed 0.4 parts of an agent (Perisea, manufactured by Asahi Kasei Chemicals Corporation, active ingredient 29.7%) and 53.6 parts of ion-exchanged water were mixed in a 140 ml mayonnaise bottle. After putting 60 parts of 2 mm glass beads, the bottle was sealed and placed in a paint shaker. After stirring for 24 hours with a paint shaker, the glass beads were removed through gauze to prepare a dispersion. The stability of the obtained dispersion and the particle size distribution (median diameter / average diameter) were measured by the following methods. The results are shown in Table 1.

Comparative Example 1
140 ml of black iron oxide (BL-100P, manufactured by Titanium Industry Co., Ltd.), 0.4 part of dispersant (Perisea, manufactured by Asahi Kasei Chemicals Corporation, active ingredient 29.7%), 53.6 parts of ion-exchanged water Of mayonnaise bottles. After putting 60 parts of 2 mm glass beads, the bottle was sealed and placed in a paint shaker. After stirring for 24 hours with a paint shaker, the glass beads were removed through gauze to prepare a dispersion. The stability and particle size distribution of the obtained dispersion were performed by the following methods. The results are shown in Table 1.

<Particle size distribution>
One drop of each dispersion was dropped into each 30 ml sample bottle containing water, and the particle size distribution was measured with a dynamic light scattering particle size distribution analyzer (Horiba LB-550).

<Stability>
Each dispersion was allowed to stand at room temperature, and the state of the liquid was observed immediately after collection until 10 days to confirm whether the pigment had settled and whether black iron oxide and carbon were separated. Evaluation was made according to the following criteria.
○: No separation or sedimentation of black iron oxide (even if there is sediment at the bottom, it can be made uniform by hand shaking)
X: Separation and sedimentation of black iron oxide

From the experimental results shown in Table 1, the black pigment dispersion produced in the examples has a smaller particle size distribution of black iron oxide and higher stability than the dispersion produced in the comparative example not containing carbon black. there were. In addition, in the dispersion of the comparative example, it was not possible to re-disperse the black iron oxide precipitated, even if it was re-stirred. It was easy to re-disperse just by shaking.

1 to 3 show SEM photographs of black iron oxide, carbon black, and the black pigment prepared in the example. It can be seen that carbon black is attached around the black iron oxide. Black iron oxide is very easy to agglomerate due to magnetism, but carbon black attached to black iron oxide prevents adhesion between iron oxides and inhibits reagglomeration, so pigment dispersion with excellent dispersion stability Is estimated to be obtained.

Since the black pigment dispersion of the present invention has very high dispersion stability, it is most suitable for various uses such as cosmetics, inkjet inks, water-based inks, and water-based paints.

Claims (3)

A black pigment dispersion containing black iron oxide, hydrophobic carbon black, and an aqueous solvent. The black pigment dispersion according to claim 1, wherein the solid content of black iron oxide is 70% by weight or less. Furthermore, the black pigment dispersion of Claim 1 or 2 containing a dispersing agent.

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