JPH0796663B2 - Method for producing pigment resin composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a pigment resin composition, and more specifically, an object thereof is to provide a pigment resin composition having excellent pigment dispersibility.

(Prior art and its problems) Conventionally, pigment resin compositions, for example, as a coloring agent for plastics, a dry color in which a pigment is mixed with a dispersant, a masterbatch in which the pigment is kneaded with a carrier resin in a high concentration, etc. are widely used. Has been done.

These plastic colorants are prepared by melting and kneading a pigment powder and a dispersant or a carrier resin with a high shearing machine such as a roll or a kneader to disperse the pigment. Since many agglomerated particles are present, it is very difficult to redisperse all of these coarse particles to several μm or less. In the conventional coloring of plastics, it is preferable that no coarse particles are present, but fine dispersion is not required so strictly.

On the other hand, in recent years, there has been a strong demand for high dispersibility of pigments even in coloring plastics, and it is becoming difficult for conventional methods using powder pigments to cope with this.

Also, as a colorant used in the field of information recording, a colorant excellent in sharpness and transparency is desired.

Therefore, an object of the present invention is to provide a pigment resin composition in which a pigment is highly concentrated and finely dispersed, for example, a colorant for a resin.

(Means for Solving Problems) The above object is achieved by the present invention described below.

That is, the present invention, an aqueous paste of the pigment, and a resin having a melting point or softening point of from room temperature to 120 ° C. is kneaded under atmospheric pressure at a temperature below the melting point or softening point of the resin in the absence of an organic solvent. Then, the pigment in the aqueous phase is transferred to the resin phase, and then water is removed, which is a method for producing a pigment resin composition.

(Function) A conventionally known pigment flushing method is used in the field of printing ink, and a method of transferring an aqueous pigment pigment to a resin layer by kneading an aqueous pigment paste and a liquid resin (varnish). Yes, or in the case of a resin that is not liquid at room temperature, the resin is dissolved in an organic solvent and used in liquid form.

In the present invention, a resin having a melting point or softening point of room temperature or higher and 120 ° C. or lower is flushed at a temperature lower than the melting point or softening point of the resin without using an organic solvent. This flushing is carried out at a temperature below the melting point or softening point of the resin, which is softened into a dough by the strong shearing action of the kneading machine in the presence of the aqueous paste of pigment, and softened into this dough. It has been found that the pigments migrate and disperse well in the resin by the action of the internal shear forces of the resin. It has been found that this dispersing action is remarkably improved as compared with a conventional flushing method in which the resin is in a solution state or a molten state, that is, the resin is in a low viscosity state.

Therefore, according to the present invention, flushing is possible even with a solid resin that is not meltable in an organic solvent, the complexity of using an organic solvent, for example, the problem of recovery of the organic solvent is solved, and high concentration and fine dispersion are achieved. The pigment resin composition of is easily provided.

(Preferred Embodiment) Next, the present invention will be described more specifically with reference to preferred embodiments.

The aqueous paste of the pigment used in the present invention is an aqueous paste obtained by producing the pigment in an aqueous phase and then filtering it without drying. Since such a pasty pigment does not undergo a drying step, the pigment particles do not secondary aggregate and remain as primary particles in most cases, and do not contain particles having a size of more than 10 μm.

As the pigment used in the present invention, any conventionally known pigment such as an azo pigment, a phthalocyanine pigment, a quinacridone pigment and a carbon black pigment can be used, and an organic pigment having high lipophilicity is particularly preferable. The solid content in the aqueous paste of the pigment is not particularly limited, but if the solid content is too low, it is uneconomical in the process, and if the solid content is too high, drying may occur on the surface to cause secondary agglomerated particles. Thus, the preferred solids range is a concentration of 10 to 70% by weight.

As the resin used in the present invention, any of the resin dispersants conventionally used as a dispersant for pigments and the resins used as a carrier resin for a masterbatch can be used. For example, polyethylene, polypropylene, each wax, etc. can be used as the dispersant, and the resin is acrylic resin, styrene resin, acrylic-styrene resin, polyester resin, epoxy resin, phenol resin, rosin-modified maleic acid resin, petroleum resin. , Alkyd resins and the like.

In the present invention, among the above resins, the melting point or softening point is room temperature or higher.
Use resin below 0 ° C.

The method of the present invention is a method in which an aqueous paste of the pigment as described above and the resin as described above are kneaded in a kneader such as a flasher to transfer the pigment in the aqueous phase into the resin. The kneading in the flasher may be performed at room temperature, but the room temperature rises to about 50 to 80 ° C. due to the frictional force in the flasher without heating, but the flushing is performed at a temperature below the melting point or softening point of the resin. .

The mixing ratio of the aqueous paste of the pigment and the resin added to the flasher varies depending on the solid content of the aqueous paste of the pigment, the type of resin, etc., but the pigment concentration of the obtained pigment resin composition is 10 to 70% by weight. preferable.

In flushing, the aqueous paste of the pigment and the resin may be charged to the full capacity of the flasher, but a preferred method is to perform the charging in several times. That is, in the first charge, both were charged to a volume of about 1/5 to 1/2 of the capacity of the flasher to perform flushing, the separated water was discharged, and then the same amount of charge was performed to perform flushing. Drain the after water. The flushing efficiency can be remarkably improved by discharging the separated water as described above.

When the final flushing is completed, the residual water is removed, and the desired pigment resin composition is obtained by heating and kneading at 100 ° C. or higher in order to further complete the removal of water.

(Effect) According to the present invention as described above, an aqueous paste of a pigment that has not been secondarily aggregated can be used without a powdering step of the pigment.
Further, by transferring the pigment from the aqueous phase to the resin phase without using an organic solvent, a colorant for plastics containing no coarse particles is provided.

(Example) Next, an Example is given and this invention is demonstrated still more concretely.
In the text, parts and% are based on weight unless otherwise specified.

Example 1 AC polyethylene 6A (allied chemical &
100 parts by Daiko Corporation and 200 parts of stable copper phthalocyanine blue pigment water paste (60 as solid content)
(Part) was kneaded in a kneader at room temperature and gradually heated as it was, and phase transition due to flushing started at 80 ° C. When kneading was continued for 20 minutes at this temperature,
The water phase and the colored resin phase were clearly separated.

Next, the kneader kneading tank was tilted to remove water, and kneading was continued to raise the temperature to 120 ° C. with the lid open to evaporate residual water.

After the water was completely removed, the mixture was cooled and solidified, and further kneaded with a heated three-roll to obtain a pigment resin composition of the present invention.

1 part of the above composition and 100 parts of polyethylene (Sumikasen G-201, manufactured by Sumitomo Chemical Co., Ltd.) were kneaded with an extruder to obtain a brightly colored resin. When this was placed on a slide glass, heated and melted, and observed under a microscope, all pigment particles were finely dispersed, and coarse particles were not observed.

Example 2 100 parts of an epoxy resin having a softening point of 100 ° C. (Epicote 1004 manufactured by Shell Petroleum Co., Ltd.) and 300 parts of Carmine 6B water paste (100 parts as a solid content) were kneaded in a kneader at room temperature, and 2 ° C./mi
When gradually heated at a heating rate of n., phase transition due to flushing started at 90 ° C. When kneading was continued for 30 minutes at this temperature, the water phase and the colored resin phase were clearly separated.

Next, the kneader kneading tank was tilted to remove water, and kneading was continued to raise the temperature to 120 ° C. with the lid open to evaporate residual water.

After the water was completely removed, the pigment resin composition of the present invention was obtained by cooling, solidifying and pulverizing.

Powder of 1 part of the above composition and 100 parts of epoxy resin were mixed and then kneaded with an extruder to obtain a vividly colored resin.

When this was placed on a slide glass, heated and melted, and observed under a microscope, all pigment particles were finely dispersed, and coarse particles were not observed.

Example 3 100 parts of a methyl methacrylate resin having a melting point of 120 ° C. (manufactured by Sanyo Kasei Co., Ltd., Hymer SBM600) and 200 parts of disazo yellow HR water paste (60 parts as a solid content) were kneaded in a kneader at room temperature, and 2 ° C./min. When gradually heated at a heating rate, a phase transition due to flushing started at 75 ° C. When kneading was continued for 30 minutes at this temperature, the water phase and the colored resin phase were clearly separated.

Next, the kneader kneading tank was tilted to remove water, and kneading was continued to raise the temperature to 120 ° C. to evaporate residual water under reduced pressure.

After the water was completely removed, the pigment resin composition of the present invention was obtained by cooling, solidifying and pulverizing.

Powder of 1 part of the above composition and 100 parts of methyl methacrylate resin were mixed and kneaded with an extruder to obtain a brightly colored resin.

When this was placed on a slide glass, heated and melted, and observed under a microscope, all pigment particles were finely dispersed, and coarse particles were not observed.

Claims (2)

[Claims] 1. An aqueous paste of a pigment and a resin having a melting point or softening point of from room temperature to 120 ° C. are kneaded in the absence of an organic solvent at a temperature below the melting point or softening point of the resin under atmospheric pressure. A method for producing a pigment-resin composition, characterized in that an aqueous phase pigment is transferred to a resin phase, and then water is removed. 2. The method of claim 1, wherein the aqueous pigment paste and the resin are added sequentially.