Compositions: coating or plastic – Materials or ingredients – Pigment – filler – or aggregate compositions – e.g. – stone,...
Reexamination Certificate
2001-12-26
2003-07-08
Green, Anthony J. (Department: 1755)
Compositions: coating or plastic
Materials or ingredients
Pigment, filler, or aggregate compositions, e.g., stone,...
C106S410000, C106S411000, C106S493000, C106S494000, C106S495000, C106S496000, C106S497000, C106S498000
Reexamination Certificate
active
06589330
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a novel green pigment composition. Specifically, the present invention relates to a novel green pigment composition that is environmentally safe because any hazardous substance will not be generated upon wasting and/or recycled use, and at the same time has a clear shade and an excellent stability.
2. Description of the Related Art
In recent years, since the environmental pollution has become serious due to the chemical substances, the promotion for solving the problem has been proposed from the viewpoint of the raw materials. Even the coloring materials such as a pigment or the like are not exception for it, the product liability for the safety of the decomposed type and secondary products which generate at the time of wasting and thermal disposal processing for the human body and environments has been examined. There has been a movement in which halide directly causing the generation of PCB and dioxin at the time of burning has to be removed from the raw materials of the products daily used.
The coloring materials of green used as a representative ecological color, at present, in almost all of the cases, are obtained by using chromium oxide green made of an inorganic pigment or cobalt chromium green, chlorination of an organic pigment or, brominated copper phthalocyanine pigment. However, since the former contains chromium, there is a problem upon wasting, the use is limited and in recent years, organic pigments have substituted for it. The latter also contains chlorine and bromine at a high ratio in the chemical structural formula, therefore, for example at the time of burning it, it has a drawback that generates a large quantity of harmful gas. However, at present, especially an organic pigment at an economical cost and having a clarity and an excellent durability which can substitute for phthalocyanine green has not been found yet, therefore, these are at present widely used as the main products for use in green colorants.
However, in recent years, in some fields, a movement intended to use only the materials, which are not the source of causing the generation of hazardous substances, has emerged. For example, as disclosed in Japanese Patent Application Charged-Open No. 2000-7974, there has been also an attempt for manufacturing a green coloring material by dispersing a blue pigment such as phthalocyanine blue or the like and a yellow pigment not containing a halogen atom into the vehicle, separately or at the same time.
However, the manufactured products of green colorants only by mixing a plurality of pigments, these are neither sufficient for endurance nor sufficient for hue being not clarified, only a green coloring material in which the separation of the colors is readily occurred particularly when it is manufactured into an ink or paint has been obtained.
SUMMARY OF THE INVENTION
The present inventors have accomplished the present invention as a result of deliberate studies of systems of green pigment compositions in hopes of solving such problems as mentioned above concerning green colorants. Specifically, having continued to make attempts to let pigment derivative materials cover particles of green pigments obtained by co-wet milling or co-dry milling of halogen-free blue pigments and halogen-free yellow pigments in the presence of milling medium, the present inventors have finally and surprisingly reached a pigment composition that is clear as a colorant and has no color separating tendency, which had not been achieved at all before the invention.
A primary object of the present invention is to provide a green pigment having no practical problems even if considering the safety and sanitary problems and environmental pollution problems while maintaining the clarified shade, an excellent light resistance and excellent heat resistance. Another object of the present invention is to provide a method of manufacturing such a green color pigment composition.
The present invention is a novel green pigment composition comprising (a) a green pigment comprising a mixture of fine particles of a halogen-free blue pigment and fine particles of a halogen-free yellow pigment and (b) a halogen-free pigment derivative.
The green pigment may be a product obtained from a co-fining process of the halogen-free blue pigment and the halogen-free yellow pigment. The pigment derivative contained in the green pigment composition is preferably in an amount of 0.2-30 wt. % based on an amount of the green pigment. The green pigment may be a product obtained by co-wetgrinding the halogen-free blue pigment and the halogen-free yellow pigment. The green pigment may also be a product obtained by co-drymilling the halogen-free blue pigment and the halogen-free yellow pigment.
The blue pigment may be at least one selected from the group consisting of phthalocyanine pigments, threne pigments, and indigo pigments. The yellow pigment may be at least one selected from the group consisting of azo, benzimidazolone, isoindoline, flavanthrone, anthrapyrimidine, anthraquinone, quinolinoquinolone, fluoroflavin and fluoruvin pigments. The pigment derivative preferably has a colorant residue and/or a triazine group.
The present invention is also a pigment dispersion comprising the green pigment composition as above-mentioned and a vehicle component.
In the green pigment composition according to the present invention, the particles of the blue pigment, the particles of the yellow pigment and the pigment derivative may be in a state of homogeneous mixture in their particle size order. Also in the green pigment composition according to the present invention, average particle sizes of primary particles constituting the blue pigment and the yellow pigment are preferably both 0.1 micron or less.
In general, pigment dispersion is a fine particle dispersion system in which each fine-size primary particle is in itself an assembly of crystallites of pigment molecules and in turn each pigment aggregate dispersed is one made of a plurality of such primary particles. In order to realize, by color mixing, a high quality green pigment composition not resulting in color separation or sedimentation, it is considered that it is essential to uniformly disperse, at their particle level of fineness, different kinds of pigment particles and secure the stability. The present inventors have considered that it may be difficult, when considering the circumstance confronted, a system composed of fine particles and where strong interfacial effect is present therefore, to attain such a desired state in the system, solely by means of the simple mixing processes of particles conventionally conducted.
A pigment immediately after being synthesized is typically composed of large particles having a size of 10 micron or more. Such a large particle is made to be fined in the subsequent pigmentation process. The fining process can be recognized as a process in which specific surface area of each pigment particle increases and the number of unstable surface molecules also increases, accordingly. Due to the existence of an extremely large number of such surface molecules, the pigment particles fined are temporarily put under an unusual condition that is thermodynamically extremely unstable and has high energy. Therefore when pigment particles of the same type, which have the same molecular structure and crystal structure and have thus an extremely high affinity each other, are once placed in a state of being finely divided and mixed, the particles tend to readily and rapidly agglomerate each other to realize an energetically stable state. In a pigment system where it has been realized based on a color mixing effect, such affinities between particles of the same kind will compete with those between particles of different kinds, and will work, as a result, to deprive of them the opportunity for mutually coming close to (or further intimately contacting) and homogeneously mixing with each other. The present inventors have considered that the consequence was just the
Kato Shigeki
Tsuji Kosaku
Green Anthony J.
TOYO INK Mfg. Co., Ltd.
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