Compositions: coating or plastic – Materials or ingredients – Pigment – filler – or aggregate compositions – e.g. – stone,...
Reexamination Certificate
2001-11-28
2003-02-18
Green, Anthony J. (Department: 1755)
Compositions: coating or plastic
Materials or ingredients
Pigment, filler, or aggregate compositions, e.g., stone,...
C106S403000, C106S404000, C106S410000, C106S413000, C106S429000, C106S447000, C106S448000, C106S464000, C106S471000, C106S487000, C106S491000, C106S494000, C106S495000, C106S496000, C106S497000, C106S498000, C106S031600, C106S031640, C106S031900, C252S587000
Reexamination Certificate
active
06521038
ABSTRACT:
BACKGROUND OF THE INVENTION
a) Field of the Invention
This invention relates to near-infrared reflecting composite pigments (hereinafter simply called “composite pigment”) each of which comprises a near-infrared reflecting and/or near-infrared transmitting colorant (which may hereinafter be collectively called “a near-infrared non-absorbing colorant”) and a white pigment coated with the near-infrared non-absorbing colorant; their production process; near-infrared reflecting coating agents, such as paints and inks, colored by the composite pigments; and near-infrared reflecting materials coated with the coating agents. The term “near-infrared” as used herein means light of 800 to 2,000 nm in wavelength.
b) Description of the Related Art
Upon coating the roof, outer walls and the like of a building or a like construction, dark-colored paints have heretofore been often used to make stains and the like on the roof, outer walls and the like hardly noticeable. Pigments employed in dark-colored paints generally include carbon black, aniline black, iron oxide black and the like. As these pigments absorb light of wavelengths ranging from the ultraviolet region to the far-infrared region, they absorb heat waves, in other words, near-infrared rays with ease so that rooms or the like of a building or a like construction tend to become hot by direct sunlight.
On the other hand, solar energy reflecting paints containing white pigments such as titanium oxide are known as paints for preventing the temperature of rooms in a building or a like construction from rising. Although these paints have thermal shield effect, they are white or light-colored paints so that stains and the like are readily noticeable. There is, accordingly, an outstanding demand for dark-colored, solar energy reflecting paints.
As dark-colored, solar energy reflecting paints, heat reflecting paints containing inorganic substances such as antimony trioxide and antimony dichromate have been proposed in JP 56-109257 A. These inorganic substances are, however, not preferred from the standpoint of environmental sanitation in that they contains heavy metals.
It has also been proposed that different from the above-described proposal, an outer wall of a building or a like construction is coated with a white paint to form an undercoat and an infrared reflecting or infrared transmitting paint is coated over the undercoat to prevent absorption of direct sunlight and hence to prevent a temperature rise in rooms. This technique, however, involves a problem in that upon performing repair work or the like, repair of the white undercoat (i.e., the coating of the white paint as the undercoat) is also needed.
In recent years, on the other hand, black pigments having properties not available from black pigments commonly used to date, such as carbon black and aniline black, are required in an increasing number of fields owing to developments of lasers, especially semiconductor lasers and sensors therefor. In the field of printing inks, for example, there is an outstanding demand for inks containing infrared reflecting black pigments. These inks make it possible to print information which are not visible to the naked eye but are readable by infrared readers. They can, therefore, be used for printing hidden barcodes or for preventing illegal copying of various printed matters.
SUMMARY OF THE INVENTION
With the foregoing circumstances in view, the present invention has as objects thereof the provision of a composite pigment of a chromatic color or black color, which is usable as a coloring agent in a paint, a printing ink or the like and, especially when employed in the paint, does not absorb near-infrared rays but reflects near-infrared rays without needing a white undercoat and also the provision of its production process.
With a view to achieving the above-described objects, the present inventors have proceeded with various investigations. As a result, it has been found that a composite pigment, which is composed of a near-infrared non-absorbing colorant of a chromatic color or black color and a white pigment coated with the near-infrared non-absorbing colorant, reflects near-infrared rays without absorption and that the room temperature of a building or the like coated with a paint making use of the composite pigment as a colorant is less susceptible to a rise by direct sunlight. Based on this finding, the present invention has been completed.
In one aspect of the present invention, there is thus provided a near-infrared reflecting composite pigment comprising a near-infrared non-absorbing colorant and a white pigment coated with said near-infrared non-absorbing colorant.
In another aspect of the present invention, there is also provided a process for the production of a near-infrared reflecting composite pigment, which comprises mixing a colorant dispersion, in which the above-described colorant is dispersed in a liquid medium, with a white pigment in a form selected from powder or a dispersion and then drying the resultant mixture.
In a further aspect of the present invention, there is also provided a near-infrared reflecting coating agent comprising as a coloring agent the above-described near-infrared reflecting composite pigment.
In a still further aspect of the present invention, there is also provided a near-infrared reflecting material comprising a base material coated on a surface thereof with the above-described near-infrared reflecting coating agent.
In the composite pigment according to the present invention, the white pigment is coated with the near-infrared non-absorbing colorant, for example, the near-infrared non-absorbing colorant is adsorbed in a finely-divided form on the surfaces of particles of the white pigments. Even when the composite pigment is dispersed in a medium, no flooding thus occurs between the white pigment and the near-infrared non-absorbing colorant. Moreover, this dispersion is substantially higher in concentration and more economical compared with a dispersion of the same amount of the near-infrared non-absorbing colorant.
As the composite pigment according to the present invention has an external appearance of a similar color as the near-infrared non-absorbing colorant and contains the white pigment as nuclei, its performance to absorb near-infrared rays is lower than that of near-infrared non-absorbing colorant itself. When employed in a paint or ink, an object coated with the paint or ink is less susceptible to a temperature rise by direct sunlight. The composite pigment according to the present invention, therefore, can show excellent near-infrared screening effect.
The near-infrared reflecting coating material—which is coated with the near-infrared reflecting agent, for example, paint comprising the composite pigment of the present invention—obviates a white undercoat or the like which has theretofore been required, thereby making it possible to exhibit near-infrared screening effect closer to the performance of the paint itself. Further, it is unnecessary to apply a white undercoat upon performing repair work or the like.
A near-infrared reflecting material can also be provided by printing or coating information with a near-infrared reflecting ink which comprises the composite pigment according to the present invention. This information is not visible to the naked eye, but is readable by an infrared reader or the like. Use of this ink makes it possible to provide a printed matter having a hidden barcode or an illegal-copying-preventing printed area.
DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS
Based on certain preferred embodiments, the present invention will hereinafter be described in further detail.
Illustrative of the near-infrared non-absorbing colorant, that is, the near-infrared transmitting or reflecting colorant for use in the present invention can include azo, anthraquinone, phthalocyanine, perinone/perylene, indigo/thioindigo, dioxazine, quinacridone, isoindolinone, isoindoline, diketopyrrolopyrrole, azomethine, and azomethine-azo organic pigments. Preferred black co
Abe Yoshio
Hosoda Tohru
Nakamura Michiei
Okamoto Hisao
Yanagimoto Hiromitsu
Dainichiseika Color & Chemicals Mfg. Co. Ltd.
Green Anthony J.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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