Bleaching and dyeing; fluid treatment and chemical modification – Nontextile – dyeing process or product – including inorganic... – Inorganic substrate
Patent
1997-11-06
1998-12-29
Einsmann, Margaret
Bleaching and dyeing; fluid treatment and chemical modification
Nontextile, dyeing process or product, including inorganic...
Inorganic substrate
8527, 8685, 8686, 534696, 534700, 534713, 534721, 534723, C09B 4516, C25D 1124
Patent
active
058534318
DESCRIPTION:
BRIEF SUMMARY
This invention is concerned with chromium 1:2 complexes, their method of manufacture and their use in dyeing anodized aluminium substrates.
Oxidized aluminium or aluminium alloys are favored by architects for facades on exterior structures due to the distinctive aesthetic appearance resulting from their surface structure. Colouration of oxidized aluminium or aluminium alloy poses a continual problem as dyes which are employed in said colouration are subjected to harsh weather conditions and in particular, exposure to direct sunlight often for long periods.
A compound having the below mentioned formula is a known dyestuff which has been utilized as a dye for aluminium. However, this compound has a tendency to fade when used in applications where long exposure to direct sunlight is involved, making it less suitable for colouration of external architectural structures. ##STR3## There remains a need to provide suitably light-stable dyestuffs which display a reduced tendency to fade when exposed to direct sunlight for prolonged periods of time.
Surprisingly we have now found that certain 1:2 chromium complexes having structures similar to that described above, but which differ at least in respect of the nitro-group arranged in para-position to the azo-group, display substantially improved light fastness.
According to the invention there is provided a compound according to the formula (I) ##STR4## wherein R.sub.1 is H or SO.sub.3 M R.sub.2 is ##STR5## M is hydrogen or a non-chromophoric cation and X.sup.+ is hydrogen or a non-chromophoric cation.
The cation may be selected from alkali metal cation, especially Li.sup.+, Na.sup.+ and K.sup.+, the ammonium cation, a mono-, di-, tri- or tetra-(C.sub.1-4 alkyl)-ammonium cation or a mono-, di- or tri-(C.sub.2-3 -alkanol)-ammonium cation.
When R.sub.2 is a naphthalenic moiety it is preferably ##STR6##
In a preferred aspect of the invention, there is provided a compound according to the formula ##STR7## wherein M and X.sup.+ are as hereinabove described.
The invention further provides a process of forming the compounds of the formula (I) comprising reacting a 1:1 chromium complex of a compound of the formula (II) with a metal-free compound of the formula (III) or reacting a metal-free compound of formula (II) with a 1:1 chromium complex of a compound of the formula (III). ##STR8##
The metallised form of compounds (II) and (II) may be obtained by reacting the corresponding chromium-free compound with a chromium-donating compound, typically chromium-III-hydroxide or a chromium-III-salt, for example chromium-III-sulphate, chromium-III-acetate, chromium-III-chloride, chromium-III-formate and chromium alums.
An alternative synthesis of the compounds of formula (I) involves the reaction of an appropriate mixture of the chromium-free compounds (II) and (III) with a slight excess of the chromium-donating compound referred to above.
The formation of the compounds according to the formula (I) may be carried out in an organic solvent miscible with water, for example, formamide, glycerin or ethylene glycol, in water or in a mixture of said solvents and water. The reaction is preferably carried out at a pH of greater than 4, i.e. slightly acidic, neutral or alkaline conditions and at a temperature of between 60.degree. to 140.degree. C.
Isolation of the compounds of formula (I) may be carried out in conventional manner, preferably by salting out and filtration. Solutions of the compound in organic solvents are diluted with water. From the aqueous solution the compound may be precipitated by cooling, possibly with addition of salts. Subsequently, the precipitated compound may be separated by filtration followed by drying and, if desired, grinding to a powder. A solution of the compound may be purified, in particular desalinated, by membrane filtration. The desalinated solution may be used as such or--if desired--be dried, e.g. spray-dried.
Depending on the reaction and isolation conditions the compounds according to the invention are obtained in free-acid form or preferably in salt f
REFERENCES:
patent: 3211512 (1965-10-01), Berger
patent: 4416816 (1983-11-01), Grossmann
patent: 5401832 (1995-03-01), Koerte
Clariant Finance (BVI) Limited
Einsmann Margaret
Jackson Susan S.
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