JPH0794633B2 - Carbon black dispersion - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a pigment paste (toner which is used as an aqueous or oil-based ink or in the production of ink or paint, in which carbon black is finely dispersed uniformly. The present invention relates to a carbon black dispersion that can be used as

(Prior Art) Carbon black (hereinafter referred to as CB) is widely used as a black colorant in the field of inks and paints, but in order to uniformly finely disperse CBs in inks and paints, a roll mill is generally used. It is necessary to use a kneading and dispersing machine such as a ball mill or a ball mill and consume a large amount of energy to loosen the CB structure and secondary agglomeration. Furthermore, it is common to use a dispersant such as a surfactant or a water-soluble polymer in order to assist dispersion and prevent sedimentation or aggregation during storage as a paint or ink, but dispersibility is sufficient even if this method is adopted. It is not satisfactory, and the dispersant used has the drawback of deteriorating the performance of the ink or paint.

In order to overcome the above drawbacks, it is necessary to modify the surface of CB to improve the dispersibility, and some methods for that purpose are known. For example, there is a method of grafting by polymerizing a vinyl monomer such as styrene in the presence of CB, but this method is not sufficient until the dispersibility of CB is sufficiently improved due to the low grafting rate. It does not.

The CB dispersion liquid in which CB as described above is dispersed in water or an organic solvent and the ink or paint obtained from it require a large amount of energy for production, or the CB dispersion, paint, or performance as an ink is insufficient. It had drawbacks.

(Problems to be improved by the present invention) The object of the present invention is that CB is uniformly finely dispersed, has excellent storage stability, is easily dispersed in ink or paint, and is sufficiently satisfactory in terms of performance. To develop a dispersion.

(Means and Actions for Solving Problems) The present inventors have found that carbon black surface-treated with poly (oxazoline) and / or a modified product of poly (oxazoline) has a high affinity with water or an organic solvent. Since it has excellent dispersibility in these media, CB dispersion can be obtained very easily, and when this is used as a pigment paste (toner) used in the production of ink or ink or paint, storage stability is improved. The present invention has reached the present invention by discovering that inks and coatings with excellent performance can be obtained.

That is, in the present invention, carbon black treated with poly (oxazoline) and / or a modified product of poly (oxazoline) (hereinafter, both are collectively referred to as polymer (A)) is dispersed in water and / or an organic solvent. The present invention relates to the obtained carbon black dispersion.

In the present invention, the polymer (A) used for the surface treatment of CB
Is a polymer obtained by ring-opening polymerization of a 2-oxazoline monomer, if necessary, by using a cyclic monomer as a copolymerization component, or by ring-opening polymerization followed by modification. (In the formula, R ₁ , R ₂ , R ₃ , R ₄ and R ₅ are independently halogen,
It is an alkyl, aralkyl, phenyl or substituted phenyl group. ), Which contains a ring-opened unit of a 2-oxazoline monomer. Those having a molecular weight in the range of 100 to 100,000 are preferably used for obtaining a carbon black dispersion having excellent properties.

Specific examples of the poly (oxazoline) in the polymer (A) include, for example, poly (2-methyloxazoline), poly (2-ethyloxazoline), poly (2-isopropyloxazoline), poly (2-butyloxazoline),
Poly (2-phenyloxazoline), poly (2-cyclohexyloxazoline), (2-methyloxazoline-
2-ethyloxazoline) copolymer, (2-ethyloxazoline-2-phenyloxazoline) copolymer, (2
-Ethyloxazoline-2-cyclohexyloxazoline) copolymer, (2-ethyloxazoline-ethyleneimine) copolymer, (2-ethyloxazoline-propylene oxide) copolymer, (2-phenyloxazoline-
Tetrahydrofuran) copolymers and the like. Specific examples of the modified poly (oxazoline) of the polymer (A) include, for example, poly (2-ethyloxazoline), poly (2-phenyloxazoline), poly (2-
Partial hydrolyzate such as methyloxazoline), poly (2-
Ethyl oxazoline), poly (2-phenyloxazoline) and other partial hydrolysates and (2-ethyloxazoline-
Alkyleneimine) copolymer and ethylene oxide,
Examples thereof include a graft reaction product with an alkylene oxide such as propylene oxide. Among them, poly (oxazoline) obtained by using one or more kinds selected from 2-ethyloxazoline, 2-phenyloxazoline and 2-cyclohexyloxazoline as a main component and a modified product of the poly (oxazoline) are industrially used. Easy to obtain,
It is desirable because the treatment effect is great. As described above, when the polymer (A) in the present invention is obtained, an alkyleneimine typified by ethyleneimine, propyleneimine and the like, and an alkylene oxide typified by ethylene oxide, propylene oxide and the like are used within a range not departing from the object of the present invention. And the like may be used as a copolymerization component of 2-oxazoline, but these alkyleneimines and alkylene oxides are preferably used in an amount of 50 mol% or less in all monomers.

In order to obtain the CB treated in the present invention, for example, a method of stirring and mixing the CB and the polymer (A) or in the presence of CB
A method of polymerizing an oxazoline monomer may be used,
Specific embodiments include, for example, (1) stirring and mixing one or more CB and one or more polymer (A) under temperature conditions of 0 ° C to 400 ° C, preferably 20 ° C to 350 ° C. And (2) treating one or more CBs and one or more polymers (A) in a suitable solvent at 0 ° C to 400 ° C, preferably 20 ° C to 350 ° C.
(3) ring-opening polymerization of a monomer containing 2-oxazoline as an essential component in the presence of at least one CB in a suitable solvent. However, in the present invention, the methods (1) and (2) are preferable for the following reasons. That is, according to the methods (1) and (2), the CB in the secondary agglomerated state is crushed during the treatment, so that the obtained CB has a fine and uniform particle size. Further, since the polymer (A) is previously prepared, the molecular weight can be easily controlled, and the polymer (A) having a particularly high molecular weight can be easily obtained. As a result, (1) ~
The carbon black dispersion using CB treated by the method (2) is particularly excellent in various properties.

As the CB in the present invention, a CB produced by a usual method such as a contact method, a fannes method, or a thermal method can be used. Particularly, as a functional group on the CB surface, a carboxyl group, a hydroxyl group and / or a quinone group is used. The use of CB having a polymer (A) used for the treatment of CB in the present invention
It is preferable that CB can be treated uniformly and with high binding property because it has a particularly good affinity with and that a carbon black dispersion having excellent dispersibility can be obtained.

When the CB treated in the present invention is obtained, the ratio of CB and polymer (A) is not limited, but the surface treatment of CB is uniformly performed, and CB and polymer (A) are firmly bonded to each other. In order to improve the dispersibility of the treated CB in the carbon black dispersion, the weight ratio of CB to the polymer (A) is 100 /.
It is preferably 1 to 100/1000, and more preferably 100/5 to 100/500.

When treating CB with the polymer (A), if necessary, an antioxidant, a heat stabilizer, a surfactant, a lubricant, and a polymer other than the polymer may be used in combination. After the treatment, antioxidants, heat stabilizers and the like can be added at appropriate times.

In the present invention, the treatment of CB with the polymer (A) is carried out by the method of the above (2), that is, CB and the polymer (A) are treated with water and / or
Alternatively, when stirring and mixing in the presence of an organic solvent, the carbon black dispersion of the present invention can be directly obtained, while CB
The treatment of (1), that is, CB and polymer (A)
In the case where only the above components are mixed by stirring, a treated carbon black dispersion can be obtained by dispersing the treated CB in water and / or an organic solvent. In dispersing the treated CB, it is not necessary to use a method of kneading under high shear using a kneader such as a roll mill or a ball mill that is usually performed to disperse the CB in a medium, and at room temperature. Alternatively, the carbon black dispersion can be obtained simply by stirring the surface-treated CB and water and / or the organic solvent under heating with a stirrer equipped with, for example, a propeller blade or a paddle blade. The carbon black dispersion of the present invention can be used as it is as an ink or as a pigment paste (toner), but if necessary, various known additives can be used for each purpose.

(Effect of the Invention) The carbon black dispersion of the present invention contains carbon black treated with poly (oxazoline) and / or a modified product of poly (oxazoline). Poly (oxazoline) or modified poly (oxazoline) can treat the surface of CB very efficiently for modification, and the resulting treated CB has excellent dispersibility in water and various organic solvents. In the carbon black dispersion of the present invention, CB is uniformly micro-dispersed, and since it is also excellent in compatibility with various resins, it is extremely easy to mix with them. Is something you can do. Therefore, the carbon black dispersion of the present invention is suitable for various uses as a coloring agent, for example, an aqueous or oily ink having excellent dispersion stability for writing, information recording or printing, and an excellent coloring power. As the above, the carbon black dispersion can be used as it is or after adding necessary components as appropriate. Furthermore, the carbon black dispersion of the present invention can be used as a pigment paste (black toner) for toning of inks, paints, plastics, etc., and can be easily dispersed in inks, paints, plastics, and It does not degrade their performance.

(Examples) Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to the following Examples. still,
Parts in the examples are parts by weight and% is% by weight.

Reference Examples 1 to 5 Carbon blacks shown in Table 1 and poly (oxazoline) and / or poly (oxazoline) modified products using Laboplast mill (manufactured by Toyo Seiki Co., Ltd.) at temperatures shown in Table 1,
Kneading reaction was carried out at 100 rpm under time conditions, and after cooling, pulverization was carried out to obtain surface-treated carbon blacks (1) to (5).

Comparative Reference Example 1 A vinyl monomer was grafted to CB, which is a known CB surface treatment method. 20 parts styrene and carbon black MA-60
10 parts of the mixture was heated under a nitrogen gas stream at 140 ° C. for 5 hours, then cooled and reprecipitated in methanol to obtain a surface-treated carbon black (1) for comparison.

Example 1 Each of the surface-treated carbon blacks (1) to (5) obtained in Reference Examples 1 to 5 and the comparative surface-treated carbon black (1) obtained in Comparative Reference Example 1 was dispersed. Carbon black dispersion (I) was added to a mixed solvent of toluene / ethyl acetate = 1/1 in an amount such that the content of CB in the liquid was 30% and stirred by a stirrer with a propeller blade.
(V) and a carbon black dispersion (I) for comparison were obtained. The particle size of CB in each dispersion was measured by the centrifugal sedimentation method. The CB concentration at the time of measurement was prepared with a mixed solvent of toluene / ethyl acetate = 1/1 so that the light transmittance was in the optimum range. The measured values are shown in Table 1 together with the particle size of untreated CB.

Example 2 Carbon Black Dispersion Liquid (I) Obtained in Example 1
(V) and the comparative carbon black dispersion (I) were added as pigment pastes to commercially available acrylic resin Aroset 5813 (manufactured by Nippon Shokubai Kagaku Kogyo Co., Ltd.),
A black enamel with PWC = 5% was prepared by stirring with a stirrer equipped with a propeller blade. The state of dispersion of the pigment was observed after leaving the enamel for 1 month. The results are shown in Table 2. An attempt was made to prepare an enamel for the untreated CB by the same method, but the agglomeration of the CB was not loosened and the enamel in which the CB was uniformly dispersed was not obtained.

Example 3 Using the surface-treated carbon blacks (1), (2) and (4) obtained in Reference Examples 1, 2 and 4, a carbon black dispersion was prepared according to the formulation shown in Table 3 to prepare an ink. Was evaluated as. In addition, an ink using a pigment paste prepared by a known method was also prepared for comparison. The carbon black dispersion (ink) thus obtained was filled in a felt-tip pen and tested for writability.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yoshinori Sano 5-8 Nishimitabicho, Suita City, Osaka Prefecture Yoshiko Nakajima Examiner, Central Research Laboratory, Nippon Shokubai Chemical Industry Co., Ltd.

Claims (1)

[Claims] 1. A carbon black dispersion obtained by dispersing carbon black treated with poly (oxazoline) and / or a modified product of poly (oxazoline) in water and / or an organic solvent.