Compositions: coating or plastic – Materials or ingredients – Pigment – filler – or aggregate compositions – e.g. – stone,...
Patent
1998-10-26
2000-12-05
Bell, Mark L.
Compositions: coating or plastic
Materials or ingredients
Pigment, filler, or aggregate compositions, e.g., stone,...
106400, 106415, 106425, 106436, 106456, C09C 100, C09C 104, C09C 122, C09C 124, C09C 136
Patent
active
061561150
DESCRIPTION:
BRIEF SUMMARY
The invention relates to multilayer interference pigments consisting of alternating layers of a material of low refractive index and of a metal or of a material of high refractive index, the central layer being formed from a transparent or semitransparent material of low refractive index.
BACKGROUND OF THE INVENTION
Multilayer pigments having alternating layers of a material of high refractive index and a material of low refractive index are known. They comprise predominantly metal oxides. However, the material of high refractive index can also be replaced by a semitransparent metal layer. The metal oxide layers are produced either by a wet method, by precipitating the metal oxide hydrates from a metal salt solution onto a substrate material, or by vapour deposition or sputtering in a vacuum. For instance, U.S. Pat. No. 4,434,010 describes a multilayer interference pigment consisting of a central layer of a reflective material (aluminium) and alternating layers of two transparent, dielectric materials of high and low refractive index, for example titanium dioxide and silicon dioxide, either side of the central aluminium layer. In a further embodiment of the pigment the layers following the central aluminium layer are formed by magnesium fluoride and chromium. This pigment is employed for the printing of securities.
JP H7-759 (A) describes a multilayer interference pigment with a metallic lustre. It consists of a substrate which is coated with alternating layers of titanium dioxide and silicon dioxide. The substrate is formed from platelets of aluminium, gold or silver, or from platelets of mica and glass which are coated with metals. This pigment has a high hiding power. For applications where high transparency of the pigmented material is required, for example for agricultural films, the pigment is unsuitable. Furthermore, it has the disadvantage that the typical depth effect of interference pigments is not produced, since the high level of reflection of the light at the metal layer which forms the core means that pigment particles lying deeper within the application medium are able to make only a very small contribution to the optical appearance. The interference effect is therefore limited to the layers located on the metal layer.
SUMMARY OF THE INVENTION
The object of the invention is to provide substantially transparent interference pigment having strong interference colours and a close angular dependency of the interference colours. Furthermore, the object of the invention is to provide pigments having special spectral characteristics in the visible range and in the infrared range.
This object is achieved according to the invention by a multilayer interference pigment consisting of a central layer of a transparent or semitransparent material of low refractive index and alternating layers of a metal or of a material of high refractive index and of a material of low refractive index on either side of the central layer.
This object is also achieved, according to the invention, by a process for preparing the novel pigment by a substrate, low refractive index and of a metal or of a material of high refractive index onto the release layer, the central layer applied being a layer of a transparent or semitransparent material of low refractive index, release layer, and washing and drying the resulting platelet-shaped interference pigment, 300.degree. C., and
The invention also provides for the use of the novel pigments for pigmenting paints, printing inks, plastics and cosmetics and for producing films.
The material of high refractive index is a metal oxide or mixtures of metal oxides with or without absorbing properties, for example TiO.sub.2, ZrO.sub.2, Fe.sub.2 O.sub.3, Fe.sub.3 O.sub.4, Cr.sub.2 O.sub.3 or ZnO, or a compound of high refractive index, for example iron titanates, iron oxide hydrates or titanium suboxides or mixtures and/or mixed phases of these compounds with one another or with other metal oxides.
The metal is preferably aluminium, chromium, nickel, a chromium-nickel alloy or silver.
REFERENCES:
patent: 5278694 (1994-01-01), Wheatly et al.
patent: 5281480 (1994-01-01), Phillips et al.
patent: 5332618 (1994-07-01), Austin
patent: 5569535 (1996-10-01), Phillips et al.
English Abstract of EP 0 753 545.
Bauer Gerd
Friz Martin
Kuntz Matthias
Pfaff Gerhard
Schank Christina
Bell Mark L.
DiVerdi Michael J.
Merck Patent Gesellschaft mit beschrankter Haftung
LandOfFree
Multilayer interference pigment with transparent central layer does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Multilayer interference pigment with transparent central layer, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Multilayer interference pigment with transparent central layer will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-957550