Compositions: coating or plastic – Materials or ingredients – Pigment – filler – or aggregate compositions – e.g. – stone,...
Reexamination Certificate
1999-02-12
2001-05-22
Green, Anthony (Department: 1755)
Compositions: coating or plastic
Materials or ingredients
Pigment, filler, or aggregate compositions, e.g., stone,...
C106S404000, C106S504000, C524S440000, C524S441000
Reexamination Certificate
active
06235104
ABSTRACT:
The invention relates to milling and dispersion medium for producing metallic pigments.
INTRODUCTION
Aluminium pigments are widely used in coating compositions particularly in paint industries to impart a metallic lustre. There are two different types of aluminium flake pigments known as leafing and nonleafing flake pigments. In leafing pigments, the aluminium flakes become arranged in a generally flat orientation at the surface of the coating to produce a mirror-like metallic finish. In the case of nonleafing aluminium flakes, the flakes are generally randomly oriented in the coating composition.
Regardless of their nature, aluminium pigments are conventionally manufactured by milling granular or spherical aluminium particles or shredded forms of aluminium foils in the presence of a desired fatty acid in a mineral spirit medium containing aliphatic and aromatic hydrocarbons. The fatty acids are hereinafter referred as lubricant. A small quantity of a suitable lubricant and a milling or grinding medium consisting of a carrier liquid, which is conventionally known as mineral spirit, is added to the aluminium particles during milling. The slurry thus formed is filtered to remove unwanted coarse particles. The paste is generally re-blended with mineral spirit to obtain a desired concentration of the aluminium metal pigment in the paste.
By the choice of milling lubricants either a ‘leafing’ type or ‘nonleafing’ pigment may be produced.
In all conventional methods of manufacture, the carrier liquids used contain volatile organic material, having small to medium range aliphatic and complex aromatic molecules. These are undesirable environmentally as a portion of these can be released to atmosphere which cause the initiation of the formation of various toxic radicals through complex photochemical processes.
The release of volatile organic material into the atmosphere from processes for producing metallic pigments is a serious problem and this invention addresses this problem.
STATEMENTS OF INVENTION
According to one aspect the invention provides the use of trans-esterified alkyl esters of vegetable oils in the manufacture and/or formulation of metallic pigment compositions.
In another aspect the invention provides a metallic pigment composition comprising a metallic pigment and an inert medium including trans-esterified alkyl esters of vegetable oils.
In a further aspect the invention provides a method of manufacturing a metallic pigment composition comprising the step of contacting metallic particles with an inert medium comprising trans-esterified alkyl esters of vegetable oils.
In one case the metallic particles are contacted with the inert medium by milling the metal in the presence of the inert medium.
Alternatively or additionally the metallic particles are contacted by blending the metallic particles with the inert medium to form a metallic paste.
The metallic particles may also be contacted by blending a metallic paste with the inert medium.
The invention also provides a coating composition in the form of a paint or ink including a metallic pigment composition of the invention.
The invention further provides a plastics composition, especially a metallised plastics composition including a metallic pigment composition of the invention.
In a preferred embodiment of the various aspects of the invention the alkyl contains from 1 to 4 carbon atoms. Most preferably the trans-esterified alkyl esters are methyl esters.
In a preferred embodiment the vegetable oil has a high content of saturated or unsaturated fatty acids. Typically the vegetable oil is selected from one or more of soybean oil, cottonseed oil, linseed oil, rapeseed oil and sunflower oil.
DETAILED DESCRIPTION
The purpose of milling and/or blending metal pigment in trans-esterified alkyl, especially methyl esters or vegetable oils, viz. soy bean oil, cotton seed oil, linseed oil, and the like, is to produce metal pigments in a non-toxic environment. Surprisingly, we have also found the added advantage that the metallic pigments produced are of improved quality and appearance. The pigments so produced showed the general tendency of improved brightness with a unique non-leafing type of pigments of highly leafing characteristics. This arises because the use of the inert medium changes the wetting properties of the metal flakes and the substrate so as to favour the orientation of the flake particles despite being a non-leafing type of material as determined by any conventional method of measurement method.
The trans-esterified alkyl, especially methyl esters derived from vegetable oils comprise mono, di, and/or tri-glycerides of fatty acids of a mixture of both saturated and unsaturated hydrocarbons. The chain length generally ranges between C
8
-C
22
, and they are mostly rich in mono and or unsaturated hydrocarbons. The inert medium used in the invention is commercially available and known as Biodiesel or Envirodiesel (Twin Rivers Technologies & Ag Products, USA).
These materials are biodegradable and of low viscosity, low volatility and of high flash point which make them safer to use as a replacement for the conventional milling medium.
The invention also provides the manufacture of aluminium pastes in which the inert medium is used for blending pastes by replacing mineral spirits to obtain products suitable for inks and plastics industries. Pigments produced according to the present invention are much more brilliant and metallic in lustre and exhibit superior colour purity. Polychromatic pain films prepared according to conventional formulations, when pigmented with aluminium paste produced according to this invention, when compared to similar films pigmented with aluminium pigment produced by conventional processes, were superior in gloss, brilliance, colour purity and exhibited higher reflectance as compared by qualitative visual means.
In a method of manufacturing a metallic pigment of the invention aluminium granules or coarse spheres are subjected to a wet comminution operation in a grinding circuit in which the metallic particles are maintained within the inert medium. The liquid bearing the comminuted particles is generally withdrawn from the comminuting operation and sieved to remove the oversize particles. The fraction containing coarser particles is returned to the grinding circuit. The fraction containing particles of desired size is removed from the circuit and subjected to filtration and blending to obtain an aluminium paste of desired metal concentration, which is normally 65 wt % of the total mass.
REFERENCES:
patent: 5122188 (1992-06-01), Erhan et al.
patent: 5221340 (1993-06-01), Nagase et al.
patent: 5556454 (1996-09-01), Bender
patent: 0232219 (1987-08-01), None
patent: 0402998 (1990-12-01), None
patent: 0455370 (1991-11-01), None
patent: WO90/03419 (1990-04-01), None
patent: WO95/14520 (1995-06-01), None
Patent Abstract for JP-60035064 A (Feb. 1985).
Barry Thomas Aquinas
Chattopadhyay Arun Kumar
Dahlia Ireland Limited
Green Anthony
Jacobson Price Holman & Stern PLLC
LandOfFree
Production of pigments does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Production of pigments, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Production of pigments will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2533270