Compositions – Organic luminescent material containing compositions – Optical brightening compositions
Reexamination Certificate
1999-09-13
2002-12-03
Koslow, C. Melissa (Department: 1755)
Compositions
Organic luminescent material containing compositions
Optical brightening compositions
Reexamination Certificate
active
06488867
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an organic fluorescent whitening pigment excellentin hiding power and more particularly, it is concerned with an organic fluorescent whitening pigment which can be utilized as coating agents for papers, coloring matters for aqueous or oily inks and inkjets, pigment components, for paints, etc., and which is capable of exhibiting excellent properties when applied to a use, in particular, needing high hiding power as well as high whiteness, for example, a coating agent for surface coating of a paper such as photographic printing paper.
2. Description of the Prior Art
Up to the present time, as a pigment component of a white pigment, there are mainly used inorganic materials, for example, titanium oxide, calcium carbonate, zinc oxide, clay, kaolin, talc, etc. On the other hand, there are no organic whitening pigment components having hiding power comparable to or more excellent than that of these pigments components. As a white organic pigment, alkylenebismelamine derivatives have been proposed as disclosed in JP-A-6-122674, which, however, are excellent in hiding power but insufficient in whiteness because of having no fluorescence.
White pigments consisting of inorganic materials of the prior art are excellent in hiding power, but when using these pigments for coating papers, for example, the whiteness of coated papers is not sufficient. Thus, in order to complement this insufficiency, various fluorescent whitening agents such as of bistriazinylaminostylbene type are ordinarily used, but this has some limitations, because the fluorescent whitening agents often meet with such a particular phenomenon as concentration quenching, i.e. that even if using in a concentration of more than certain value, not only more whitening effect cannot be obtained, but also a yellowish hue is rather given. Accordingly, the fluorescent whitening agent can only be used with a very low concentration.
Generally, inorganic pigment components naturally have large densities and when preparing dispersed compositions therefrom, the pigment components tend to be separated and settled, so that a uniform and stable dispersed composition is hard to be prepared. This is not preferred from the stand-point of the storage stability of the pigment dispersed composition. Further, when such a pigment composition is coated onto a paper, for example, the weight of the coated paper is increased. In addition, the inorganic pigment generally has a disadvantage that its compatibility with binders and other reagents required for preparation of the pigment composition is inferior.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an organic fluorescent whitening pigment having an excellent hiding power as well as high whiteness, that inorganic pigment compositions cannot achieve, whereby the above described problems of the prior art can be solved.
It is another object of the present invention to provide a coating agent for coating a surface of a paper, containing an organic fluorescent whitening pigment having an excellent hiding power as well as high whiteness.
These objects can be attained by an organic fluorescent whitening pigment composition having an excellent hiding power, comprising, as a pigment component a complex salt (compound) represented by the following general formula:
in which X represents same or different hydrogen atom, methyl, ethyl, methoxy, ethoxy, sulfo group or chlorine atom, R
1
represents an alkyl, alkenyl, aralkyl, aryl or cycloalkyl group, and R
2
, R
3
and R
4
independently represent hydrogen atom or R
1
, two or three groups of R
2
, R
3
and R
4
being capable of forming a heterocyclic group with nitrogen atom in each case.
DETAILED DESCRIPTION OF THE INVENTION
The inventors have made various efforts to solve the above described disadvantages of the inorganic white pigments and consequently, have found that a complex salt obtained from some fluorescent whitening agent and quaternary ammonium compound has very excellent properties as an organic white pigment component. The present invention is based on this finding.
The features of the present invention and embodiments thereof will now be summarized below:
(1) An organic fluorescent whitening pigment composition having an excellent hiding power, comprising, as a pigment component, a complex salt (compound) represented by the following General Formula:
in which X represents same or different hydrogen atom, methyl, ethyl, methoxy, ethoxy, sulfo group or chlorine atom, R
1
represents an alkyl, alkenyl, aralkyl, aryl or cycloalkyl group, and R
2
, R
3
and R
4
independently represent hydrogen atom or R
1
, two or three groups of R
2
, R
3
and R
4
being capable of forming a heterocyclic group with nitrogen atom in each case.
(2) The organic fluorescent whitening pigment composition having an excellent in hiding power, as described in the above (1), wherein the pigment component is a complex salt (compound) represented by the following formula:
The above described complex salt of the present invention is a substantially water-insoluble fluorescent complex salt, represented by the following general formula:
in which X, R
1
, R
2
, R
3
and R
4
have the same meanings as described above, which can be obtained by reaction of a bis-stilbenesulfonic acid derivative or its water-soluble salt, in particular, an alkali metal salt, whose anionic component of the fluorescent whitening agent is generally represented by the following General Formula (I):
in which X represents same or different hydrogen atom, methyl, ethyl, methoxy, ethoxy, sulfo group or chlorine atom, with a quaternary ammonium compound represented by the following General Formula (II):
in which Y represents a colorless, non-fluorescent, water-soluble anion or OH
−
, R
1
represents an alkyl, alkenyl, aralkyl, aryl or cycloalkyl group, R
2
, R
3
and R
4
independently represent hydrogen atom or R
1
or R
2
, R
3
and R
4
can form a heterocyclic group with nitrogen atom in each case.
Furthermore, an organic fluorescent whitening pigment excellent in hiding power can be obtained, consisting of this complex salt as a predominant component.
Other embodiments of the present invention are coating compositions for fluorescent papers comprising the above described fluorescent complex salt mixed in coating compositions for papers, or fluorescent white ink compositions for ink jets comprising the above described fluorescent complex salt mixed in white ink compositions for ink jets, processes for the production of the same, methods of using the same, various materials using the same, in particular, coated papers having excellent hiding power and high whiteness, for example, photographic printing papers (photographic papers), etc.
In white pigment compositions for coating papers or plates, clays, calcium carbonate, titnaium oxide, etc. have hitherto been used as a white pigment component. This is mainly due to the excellent hiding power that these white pigments have.
As a result of our studies, it is found that the organic white pigment of the present invention has more excellent hiding power than the inorganic white pigments consisting predominantly of the above described materials. Further, the white pigment of the present invention is so fluorescent that when using the pigment, a higher whiteness that the prior art cannot reach can be obtained. In addition, this fluorescent property does not exhibit concentration quenching that appears in ordinary fluorescent whitening agents (such a peculiar phenomenon to fluorescent whitening agents that when using a fluorescent whitening agent with a concentration higher than a certain value, the whitening effect is rather lowered to render yellowish sometimes). Thus, the white pigment of the present invention can be used in such a high concentration that cannot be considered in the prior art.
The fluorescent whitening pigment component of the present invention has a smaller density, because of being organic, than inorganic pigments. Accord
Matsumoto Shigehiro
Matsumoto Shigekazu
Shimabukuro Kunio
Yanagisawa Takao
Hakkol Chemical Co., Ltd.
Koslow C. Melissa
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