JPH05331780A - Cationic aqueous dispersant for pigment - Google Patents

Abstract

PURPOSE:To provide the subject dispersant containing a specified cationic polymer and an anionic surfactant in a specified amount based on the cationic monomer constituting the cationic polymer, suitable for dispersion of a pigment and excellent in dispersion in water. CONSTITUTION:The objective cationic dispersant excellent in dispersion properties and stability and suitable for dispersion of an organic or inorganic pigment is obtained by using a cationic polymer containing a cationic monomer-derived structural unit having a tert-amino group or a quaternary ammonium group, preferably a dialkylaminoalkyl (meth)acrylate-derived structural unit in combination with an anionic surfactant, preferably a condensate between formalin, an aromatic sulfonic acid and naphthalenesulfonic acid in an amount of 5 to 70mol% based on the cationic monomer constituting the cationic polymer. In addition, coloration of paper or pulp is carried out, e.g. by adding the pigment dispersant in a process from beating of pulp to papermaking.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cationic aqueous dispersion of a pigment excellent in dispersibility and stability, a cationic aqueous dispersion of a pigment and a colored paper colored with the cationic aqueous dispersion. ..

[0002]

BACKGROUND OF THE INVENTION Cationic aqueous dispersions of pigments are used for papermaking, cationic water-based coatings, cationic electrodeposition coatings, leather,
Although it is useful as a colorant for inks for stationery and ink jet recording paper, at present, no cationic aqueous dispersion of a pigment is provided because there is no suitable cationic dispersant.

In general, cationic activators have poor pigment dispersibility, and a good pigment aqueous dispersion cannot be obtained.

On the other hand, when the cationic polymer is used as a dispersant for an aqueous pigment dispersion, the cationic polymer having a tertiary amino group is neutralized with an acidic compound to solubilize the aqueous resin solution. The cationic resin having a quaternary ammonium group shows weak acidity in the resin aqueous solution.

As is well known, the charging state of pigment particles in various aqueous solutions is positively charged when the pH of the aqueous solution is acidic from the isoelectric point of the pigment, and negatively charged when the pH is basic.

For this reason, in the cationic polymer resin solution, the pigment is positively charged and an electrostatic repulsive force is generated between the pigment and the positive charge of the resin, so that dispersion stabilization by resin adsorption is insufficient. There was a drawback that a good aqueous dispersion could not be obtained due to poor dispersibility and poor dispersion stability.

[0007]

DISCLOSURE OF THE INVENTION The present invention improves conventional cationic polymer resins and provides a cationic aqueous dispersant for pigments and a cationic aqueous dispersion for pigments which are excellent in dispersibility and dispersion stability. It is what

[0008]

The present invention provides a cationic polymer having a tertiary amino group or a quaternary ammonium group as a dispersant, and a cationic monomer constituting the cationic polymer. A cationic aqueous dispersant for a pigment, comprising 5 to 70 mol% of an anionic activator, a cationic aqueous dispersion of a pigment dispersed using the cationic aqueous dispersant, and a cationic property of the pigment. A colored paper colored with an aqueous dispersion.

In the present invention, since the amount of the anionic activator is 5 to 70 mol% of the cationic monomer, the cationic property is not impaired.

The cationic polymer may have a single or both tertiary amino groups or quaternary ammonium groups, and not only the polymers of these cationic monomers but also copolymers thereof. Copolymers with possible nonionic monomers can also be used.

As the cationic monomer for obtaining the cationic polymer used as the dispersant of the present invention, (1) a tertiary amino group-containing monomer

A) Alkylaminoalkyl (meth) acrylamide dimethyl or diethylaminoethyl (meth) acrylamide, dimethyl or diethylaminopropyl (meth) acrylamide and the like.

B) Dialkylaminoalkyl (meth) acrylate dimethyl or diethylaminoethyl (meth) acrylate, dimethyl or diethylaminopropyl (meth) acrylate
Acrylate etc. (2) Quaternary ammonium group-containing monomer

A) (meth) acryloyloxyalkyltrialkylammonium salt 2- (meth) acryloyloxyethyltrimethylammonium chloride, 3- (meth) acryloyloxy-2
-Hydroxypropyl trimethyl ammonium chloride and the like.

B) (meth) acrylamidoalkyltrialkylammonium salt 3- (meth) acrylamidopropyltrimethylammonium chloride, 3- (meth) acryloylamino-
2-hydroxypropyltrimethylammonium chloride and the like.

C) Others Dimethyl or diethyl diallyl ammonium chloride, β-vinyloxyethyl trialkyl ammonium salt, vinyl benzyl ammonium salt and the like. Can be mentioned.

Among these cationic monomers, dialkylaminoalkyl (meth) acrylate is preferable.

The nonionic monomer polymerizable with the cationic monomer to obtain the cationic polymer used as the dispersant of the present invention includes, for example, acrylamide, acrylonitrile, styrene, alkyl ester salts of acrylic acid or methacrylic acid. And the like, and of these, preferred are alkyl ester salts of acrylamide, acrylic acid or methacrylic acid.

Examples of the anionic activator used in combination with the cationic polymer used as the dispersant of the present invention include alkylbenzene sulfonates, alkylnaphthalene sulfonates, alkylsulfosuccinates, alkyldiphenyl ether disulfonates, and naphthalene sulfonates. Examples thereof include acid formalin condensate, alkylnaphthalene sulfonic acid formalin condensate, aromatic sulfonic acid formalin condensate, and lignin sulfonate.

Of these, preferable are formalin condensates of aromatic sulfonic acids and naphthalene sulfonic acids.

Next, as an effective amount of the dispersant to be used for the pigment, the amount of the cationic polymer is 0.5 to 1 with respect to the pigment.
00 wt%, preferably 5 to 50 wt%, and the amount of the anionic activator is 5 to 70 mol%, preferably 5 to 50 mol% of the cationic monomer constituting the cationic polymer.

The anionic activator to be used in combination with the cationic polymer may be used by mixing the cationic polymer and the anionic activator in an unmixed state, or by adding the anionic activator to the pigment in advance to a certain extent. There are a method of dispersing and then adding a cationic polymer to disperse, and a method of previously mixing a cationic polymer and an anion activator to use as a polysalt. Of these, the most preferable method is to use it as a polysalt.

Further, the anionic activator is effective even if the amount of the anionic activator is surface-treated before the pigment synthesis step or the post-treatment step, or after the production.

As the pigment used in the present invention, any known pigment can be used. As an organic pigment,
Azo pigments, dye lake pigments, phthalocyanine pigments, condensed polycyclic pigments, quinacridone pigments, dioxazine pigments and isoindolinone pigments, and inorganic pigments include red iron oxide, yellow lead, vermilion, titanium oxide and carbon black. Any pigment may be used depending on the hue and the application.

In order to clarify the present invention, the method for producing the cationic polymer used in the present invention is shown as a reference example, and then the examples of the present invention will be specifically described. The middle part of an example shows a weight part.

[0026]

[Reference example]

Reference Example 1 Isopropyl alcohol 243 was placed in a flask equipped with a dropping funnel, a thermometer, a nitrogen gas introduction tube, a reflux condenser, and a stirrer.
And 2.4 parts of azobisisobutyronitrile are charged and heated to 80 ° C. while passing nitrogen gas. After that, a mixture of 85.2 parts of butyl methacrylate and 157 parts of dimethylaminoethyl methacrylate was added dropwise over 2 hours, heating was continued for 2 hours, 2.4 parts of azobisisobutyronitrile was added, and heating was continued for 1 hour. Is cooled to 50 ° C. or lower, and 100 parts of 37% hydrochloric acid and 537 parts of water are added. The obtained resin solution was transferred to a distillation flask and 95% of the isopropyl alcohol used was distilled off to obtain a resin solution having a solid content of 27%. This polymer is called a cationic polymer-1.

Reference Example 2 A device similar to that used in Reference Example 1 was charged with deionized water 105.
Part, 1 part potassium persulfate, and while passing nitrogen gas 8
Heat to 0 ° C. Thereafter, 100 parts of dimethylaminoethyl methacrylate was added dropwise over 2 hours, heating was continued for another 2 hours and cooled to room temperature, and 126 parts of 30% acetic acid was added to obtain a resin solution having a solid content of 30%. This polymer is called a cationic polymer-2.

Reference Example 3 615 parts of deionized water was charged in the same apparatus as used in Reference Example 1, heated to 70 ° C. while passing nitrogen gas, and 2.
Add 1 part of 2'-azobis (2-amidinopropane) hydrochloride and then heat to 80 ° C. Thereafter, 34 parts of methyl methacrylate and 194 parts of 2-methacryloyloxyethyltrimethylammonium chloride were simultaneously added dropwise over 2 hours, and heating was continued for another 2 hours to obtain a solid content of 27
% Resin solution was obtained. This polymer is a cationic polymer-
Let's call it 3.

Reference Example 4 450 parts of deionized water was charged in the same apparatus as used in Reference Example 1, heated to 70 ° C. while passing nitrogen gas, and 2.
Add 1 part of 2'-azobis (2-amidinopropane) hydrochloride and then heat to 80 ° C. Thereafter, 194 parts of 2-methacryloyloxyethyltrimethylammonium chloride was added dropwise over 2 hours, and heating was continued for another 2 hours to obtain a resin solution having a solid content of 30%. This polymer will be referred to as a cationic polymer-4.

Reference Example 5 A device similar to that used in Reference Example 1 was charged with deionized water 688.
Parts, dimethyldiallylammonium chloride 72.5
And 3.6 parts of acrylamide were added and dissolved. To this solution, 0.5 part of ammonium persulfate was added, heated to 50 ° C. while passing nitrogen gas, and continuously heated for 24 hours.
A 9% resin solution was obtained. This polymer is called a cationic polymer-5.

[0031]

[Examples and Comparative Examples]

Examples 1 to 5 and Comparative Examples 1 to 5 Compositions in which the cationic polymers (cationic polymers-1 to 5) obtained in Reference Examples 1 to 5 and the anionic activator were used in combination as Examples, As a comparative example, Table 1 shows the composition when the cationic polymers obtained in Reference Examples 1 to 5 (cationic polymers-1 to 5) are used alone.

[0032]

[Table 1]

After thoroughly mixing the mixture having the composition shown in Table 1 by high-speed stirring, a sand mill treatment was performed. Table 2 shows the state at that time and the dispersibility and dispersion stability of the obtained dispersion.

[0034]

[Table 2]

The dispersibility and dispersion stability of the obtained dispersion are B
The viscosity was evaluated by a viscosity (cps, 60 rpm) using a viscometer, and the dispersion stability was evaluated by heating the dispersion in a constant temperature bath at 50 ° C. for 7 days.

As shown in Table 2, the cationic aqueous dispersion of the pigment according to the present invention has excellent dispersibility and dispersion stability,
It is useful as a coloring agent in the field where a cationic aqueous dispersion of a pigment is required, and is particularly suitable for coloring paper and pulp.

The methods for coloring paper and pulp include (1) an internal addition method in which a pigment is added for coloring during or after beating of the pulp and before the papermaking, and (2) a size press after papermaking. The method is roughly classified into an external addition method in which a pigment is added to the size press liquid in the process, and a method of overcoating the surface of the paper with a coating liquid prepared from an inorganic white application material, a binder and the like is also used.

The cationic aqueous dispersion of the present invention can be applied to any method, but the internal addition method is more preferable.

In the internal addition method, first, pulp is beaten with a pulper, a refiner or the like to a predetermined beating degree to form a pulp slurry, to which a normal sizing agent, a sulfuric acid band, a paper strengthening agent and a fixing agent are added. After adding as necessary, usually 0.01 to 20% (vs. pulp%) equivalent of a cationic aqueous dispersion of the pigment of the present invention is added, and then the paper is subjected to a papermaking process and a drying process by a conventional method to be colored. Get the paper.

Example 6 Hardwood bleached kraft pulp (beating degree 32 ° S) in 50 parts of water
R) was added in 2 parts (dry weight), the mixture was stirred for 3 minutes, and then added to 0.
07 parts of rosin-based sizing agent (Size Pine E, manufactured by Arakawa Chemical Industries KK) was added and stirred for 3 minutes. Then, 0.06 parts of crystalline aluminum sulfate was added and stirred for 3 minutes. Finally, 0.02 part (to pulp 1%) of the cationic aqueous dispersion of the present invention prepared in Example 1 was added and stirred for 5 minutes. Then, papermaking and drying are performed according to the method described in JIS P-8209 (method for preparing hand-wound paper for pulp test).

In the same manner, 0.2 parts (10% of pulp) and 0.4 parts (2% of pulp) of the cationic aqueous dispersion were prepared.
0%) was used for papermaking and drying. The paper thus obtained showed a clear yellow color value, excellent build-up properties, and a small difference between front and back sides.

Example 7 Hardwood bleached kraft pulp (beating degree 32 ° S) in 50 parts of water
R) was added in 2 parts (dry weight) and stirred for 3 minutes, after which the cationic aqueous dispersion of the present invention prepared in Example 4 was added to 0.2 wt.
Add 04 parts (2% to pulp), stir for 5 minutes, then add JI
Paper was made and dried according to the method described in SP-8209 (Handmade paper preparation method for pulp test). The thus-obtained papermaking paper showed vivid blue with color value and was excellent in color development.

Comparative Example 6 On the other hand, a commonly used aqueous dispersion for papermaking coloring (dispersion of formalin condensate of sodium naphthalene sulfonate of pigment CI Pigment Blue 15 used in Example 4) In the same manner as described above, a paper made by coloring in the same manner (with an equivalent amount of the same pigment added) and a paper made by drying were only slightly colored blue.

The coloring properties of the colored papers obtained in Example 7 and Comparative Example 6 were compared. For comparison, the reflectance of the felt surface of the obtained colored paper was measured, converted into a K / S value, and the coloring power of the high-density colored paper (Example 7) was set to 100% to compare the coloring properties. In this comparison, the coloring property of the colored paper of Comparative Example 6 was 4.

[0045]

INDUSTRIAL APPLICABILITY The present invention is an improvement over the conventional cationic polymer resin, and it is possible to obtain a cationic aqueous dispersant for pigment and a cationic aqueous dispersion for pigment which are excellent in dispersibility and dispersion stability. The cationic aqueous dispersion of this pigment is useful as a coloring agent for papermaking and other purposes, and has the effect that it can be provided for the first time according to the present invention.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location C09C 3/10 PCC 6904-4J D06P 1/52 7306-4H D21H 19/36

Claims (3)

[Claims] 1. A cationic polymer having a tertiary amino group or a quaternary ammonium group as a dispersant, and 5 to 70 mol% of a cationic monomer constituting the cationic polymer.
1. A cationic aqueous dispersant for pigments, which comprises an anionic activator. 2. A cationic aqueous dispersion of a pigment dispersed using the dispersant according to claim 1. 3. A colored paper colored with the cationic aqueous dispersion of the pigment according to claim 2.