Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2000-10-05
2002-01-22
Cain, Edward J. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S442000, C524S444000, C524S445000, C524S451000, C106S450000, C106S461000, C106S462000, C106S471000, C523S171000, C523S205000, C523S209000, C523S210000, C523S216000
Reexamination Certificate
active
06340723
ABSTRACT:
TECHNICAL FIELD OF INVENTION
The present invention relates to a highly orientated flaky pigment excellent in plane orientation (leafing effect). In particular, the present invention relates to a novel highly orientated flaky pigment excellent in plane orientation, which has been surface-treated with a fluorine-containing phosphate compound to improve the coloristic property and gloss of the flaky pearl pigment.
BACKGROUND ART
A flaky pigment with a pearl gloss (referred to hereinafter as “flaky pearl pigment”) is a pigment prepared by coating on the surface of a flaky base material with a transparent or semitransparent metal oxide having high refractive index such as titanium dioxide, zirconium oxide and iron oxide, showing a pearl gloss resulted from mutual interfering action between reflection of incident light from a flaky substrate/coating layer interface and reflection of incident light from the surface of the coating layer, and this pigment is widely used in various fields such as paints, inks, plastics and cosmetics. As the flaky pearl pigment itself is composed of inorganic materials as described above, it has quite high polarity and high hydrophilicity. Therefore, its lipophilicity is poor, and its affinity to an organic medium is lower. Accordingly, due to its poor dispersibility, there appears problem that the flaky pearl pigment cannot be used independently. Hence, in order to improve their weather resistance and anti-yellowing property according to different uses, surface treated flaky pearl pigments with various methods have been proposed (e.g. for paints, JP-A 63-130673, JP-A 1-292067 etc.; for plastics, JP-A 4-296371, JP-A 5-171058, JP-A 9-48930 etc.).
However, the majority of these known techniques are concerned basically with treatment for the purpose of improving the affinity of the flaky pearl pigment to mediums, and offer only improvement in dispersibility (wettability) in a medium such as inks, paints and plastics, the orientation of the flaky pearl pigment readily becomes random in the medium, so the original characteristics resulting from the shape of the flaky pearl pigment cannot be sufficiently demonstrated. That is, there was the problem that it was impossible to arrange the flaky particle planes of the flaky pearl pigments to parallel to a printed surface or a coated surface (this arrangement is referred to hereinafter as “plane orientation”) in order to achieve the adequate original effect of the pigment on chroma and gloss. The probability of attaining plane orientation can be increased to a certain degree by improving or devising the method of printing or painting, but it is still insufficient to achieve the adequate effect. Accordingly, there is a great demand in the market for demonstration of the characteristics originated from the shape of the flaky pearl pigment (the improvement in coloristic property etc. by plane orientation is also referred hereinafter to as leafing effect). The technical problem with this demand is that it is necessary for the flaky pearl pigment to maintain suitable affinity to prevent mutually aggregation of powdered particles in a medium constituting an ink, paint, plastic etc., and also simultaneously to float the pigment powdered particles on the surface of the medium without dispersing them into the inside of the medium, therefore the delicate balance is required for setting up this condition.
On the other hand, phosphates having perfluoroalkyl groups (referred to hereinafter as fluorine-containing phosphate compounds) have been proposed as a treating agent for powder to render hydrophobicity and oleophobicity on cosmetics (JP-A 5-39209, JP-A 5-124932, JP-A 9-30935 etc.), but they are not aimed directly at the leafing effect for the purpose of improving the characteristics of the flaky pigment. Furthermore, these prior art techniques make use of a method (a) where the fluorine-containing phosphate compound is dry-mixed directly with powder or a method (b) where the fluorine-containing phosphate compound is previously dissolved in a soluble solvent, and the resulting solution is dry-mixed with powder and dried, and therefore, these methods are aimed at mere physical adsorption but not at chemical adsorption, resulting in weak binding and inadequate duration and stability of the effect. In fact, there appears the problem that when such fluorine-containing ester compounds are added to inks, paints, plastics etc., their effect is not satisfactory, and the characteristics of the pigment at the initial stage are lowered through the operation of mixing with other medium components. Further, there existed another problem that because uniform adsorption is difficult in the dry mixing process, a long time is necessary for mixing and stirring, resulting in destruction of flaky base materials.
DISCLOSURE OF THE INVENTION
As a result of their eager investigation to improve the characteristics of the flaky pearl pigment, the present inventors found that upon treating the flaky pigment with a hydrated metal oxide and then surface-treating it with a fluorine-containing phosphate compound, the flaky pearl pigment is endowed with excellent plane orientation to exhibit an excellent leafing effect as a pigment for inks, paints, plastics or cosmetics. On the basis of this finding, the present invention was made.
That is, the present invention provides the novel highly orientated flaky pigment, the process for producing the same and the ink, paints, plastics and cosmetics comprising said pigment.
1. A highly orientated flaky pigment being excellent in plane orientation, characterized in that a hydrated metal oxide and one or more phosphates selected from phosphates having perfluoroalkyl groups represented by the general formulae (A) and (B) shown below or salts thereof are coated one after another on the surface of a flaky pigment with a pearl gloss. The general formulae:
(A) (RfC
n
H
2n
O)
m
PO(OM)
3−m
(B) (RfSO
2
NRC
n
H
2n
O)
m
PO(OM)
3−m
wherein Rf is the same or different and represents linear or branched C
3
to C
21
perfluoroalkyl group or perfluoroxyalkyl group, n is 1 to 12, m is 1 to 3, M represents hydrogen, alkali metal, ammonium group or substituted ammonium group, and R represents hydrogen or C
1
to C
3
alkyl group.
2. The highly orientated flaky pigment according to item 1 above, characterized in that the metal component in the hydrated metal oxide comprises one or more metals selected from aluminium, zinc, calcium, magnesium, zirconium and cerium, and the amount thereof in terms of metal oxide is 0.1 to 20% by weight relative to the flaky pearl pigment.
3. The highly orientated flaky pigment according to item 1 or 2 above, characterized in that the amount of the phosphates having perfluoroalkyl groups represented by the general formula (A) or (B) shown above or salts thereof is 0.1 to 20% by weight relative to the flaky pearl pigment.
4. A highly orientated flaky pigment characterized in that the highly orientated flaky pigment according to any one of item 1 to 3 is surface-treated further with a polymer selected from cellulose compounds and poly(meth)acrylate compounds.
5. A process for producing a highly orientated flaky pigment, characterized in that a flaky pigment is suspended in water, the pH of the suspension is adjusted to no less than the neutralization hydrolysis point of a metal salt, then an aqueous solution of one or more metal salts selected from aluminium, zinc, calcium, magnesium, zirconium and cerium is added to the suspension while keeping its pH constant with an aqueous alkali solution, and after addition, its pH is adjusted to no more than the pH at the neutralization hydrolysis point of the metals, an aqueous solution of phosphates having perfluoroalkyl groups represented by the general formula (A) or (B) shown in above or salts thereof is added to the resulting suspension under stirring, and after the addition, its suspension is filtered, washed with water and dried.
6. Inks, paints, plastics or cosmetics containing the highly orientated flaky pigment according to any one of items
Li Bangyin
Nitta Katsuhisa
Cain Edward J.
Merck Patent Gesellschaft mit beschraenkter Haftung
Millen White Zelano & Branigan P.C.
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