Compositions: coating or plastic – Materials or ingredients – Pigment – filler – or aggregate compositions – e.g. – stone,...
Reexamination Certificate
2001-05-15
2003-06-03
Marcheschi, Michael (Department: 1755)
Compositions: coating or plastic
Materials or ingredients
Pigment, filler, or aggregate compositions, e.g., stone,...
C106S465000
Reexamination Certificate
active
06572694
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates to surface coatings. In particular, the invention in its simplest form relates to a composition comprising a color pigment and a pigment spacer. Further, the present invention relates generally to the field of composite pigments, and relates more specifically to composite pigments comprising an inorganic pigment and calcium carbonate as a pigment extending composition.
2. Prior Art
Calcium carbonate (CaCO
3
) has been used for hundreds of years in combination with colored pigments both as a finish on houses, such as whitewash, and by artists, who would bind pigments into freshly applied lime, known as fresco. Quite possibly, marble dust was mixed with pigment to achieve special color effects in oil-based artist paints and watercolors. There is very little documentation on this, as an artist's technology was closely guarded, rarely written down, and only passed on to his or her apprentice of sufficient skill and intention to become artists in their own right. This system maintained the secrecy of the technology and has largely been lost. Industry today largely still follows this apprenticeship system, with each company closely guarding their formulations to maintain market advantage.
Inks are both simple and complex. Inks are simple because the amount of pigment from one brand to another must deliver the same performance (the number of pages printed per unit of ink). Assuming equivalent cost, the brand of ink that produces the greatest number of printed pages will be preferred. Inks are complex because they have certain properties that must be controlled, as the transfer physics of ink must allow the ink to spread thinly, evenly, and without fault. Each company has their combinations of binders that allow modifications of the various properties of inks to compensate for changes in the raw materials used, as well as allowing changes to the properties of the inks for special applications (such as printing on plastics, uneven surfaces, difficult to apply surfaces, for example). However, the amount of pigment in a unit of ink will not change to produce the same number of printed pages.
Paints are significantly different from inks in so far as the final properties of paints are more variable. House or architectural paints must cover opaquely in as few coats as possible with the appropriate surface finish (gloss, matte, exterior, interior, solvent resistance, sun resistance, weather resistance, dirt resistance, scuff resistance, washability, chalking, for example). To formulate paint, one needs first a sufficient amount of pigment to give satisfactory opacity with a minimum number of applications. Each type of paint will have a range of formulation possibilities and will have to deliver the performance expected by the market place. An exterior paint for metal surfaces, such as tanks and containers, will have to protect the metal as well as give a durable shiny coating. In this case, pure pigments with as few fillers as possible will have to be used, as room must be left in the formulation to use a greater amount of gloss binder and rust inhibitors, surface cleaners, catalyzers, driers, and solvents, for example. Interior flat finish house paint can have much greater latitude in formulation. In this case, the flat or matte finish can be achieved by using less glossy binders, or by leaving particles on the surface of the paint that will scatter light (dry hide) or by using high surface area materials such as fumed silicas to scatter the light, diatomaceous skeletal powders to present sharp projections on the surface to scatter the light, or by carefully balancing the binders, pigments, and fillers to give a surface that appears flat but has scuff resistance and good washability, for example.
Both inks and paints have a range of formulation possibilities, and a great departure from the balanced characteristics of each system will not be tolerated by the industry or the consumer. As a consequence, the many thousands of formulators who have great experience in maintaining a viable coating system will not remove a major portion of one of the components of their formula and will not replace any major component with an even larger amount of other material, such as transparent fillers. Further, formulators are hesitant to explore changing the ratios of materials outside of the accepted range of performances for those materials. As a result, those skilled in the art would not expect a major boost in performance of the colored pigments by reducing the pigment loading by 25% and adding a transparent material twice the weight of the pigment removed. Thus, those skilled in the art would not have explored filler materials such as CaCO
3
looking for a sudden and counterintuitive boost in pigment performance.
As recently as the 1960's and 1970's much effort was directed towards boosting the performance of TiO
2
to give greater efficiencies. Microencapsulation was explored and the spacing of the TiO
2
was deemed critical to boosting performance. The gain at most was one or two percent. No one of skill in the art was looking for 35% gains in performance, as this was counterintuitive.
The demand and supply for titanium dioxide, which is a major and the most expensive component of titanium dioxide pigments, has continuously grown over the last 40 years and industry analysts project that the demand will increase between 3 and 4 percent per year through 2005. While the demand for titanium dioxide is growing, the supply of titanium dioxide may not be able to keep up with the growing demand because the supply may remain limited due to limitations in the operating capacity.
As a consequence of the supply and demand divergence, the price of titanium dioxide and titanium dioxide pigments is likely to elevate over the next years. Despite major plans by the titanium dioxide (TiO
2
) producers to increase production, such increases may not be immediate or affect the supply immediately. The producers to justify adding newer TiO
2
capacity and to compensate for the price increase in the raw material costs could seek price hikes. These price hikes will make the most expensive part of titanium dioxide pigments even more expensive.
Because of potentially rising price of titanium dioxide and the limited supply of titanium dioxide, there is a need for pigment technology that can use less of the expensive titanium dioxide in the pigment without sacrificing significant amount of pigment quality. However, the optical activity of a pigment composition is affected by the dispersion of a pigment within a pigment composition. Thus, flocculation of pigment will reduce the optical intensity of the ink.
The prior art discloses technology that attempts to use less of the expensive component.
U.S. Pat. No. 2,877,130 to Caron et al. discloses a paint-base material that is devoid of hiding powers in the absence of an active pigment. Caron '130 discloses a paint-base composition, which can comprise between 22 to 56% of a final pigmented paint composition that can include an extender such as calcium carbonate, which can vary from 12 to 40%. In the examples disclosing final paint formulas, Caron '130 includes formulas containing less than 17% calcium carbonate of the total pigment composition. Although Caron '130 discloses a calcium carbonate range, it only discloses a paint-base (rather than a paint) and the disclosed final paint formulas contain less than 17% calcium carbonate.
U.S. Pat. No. 4,826,535 to Godly discloses tempera paint or a water-based composition that can be removed during normal washing. The composition disclosed in Godly '535 includes a carbon dioxide liberating substance, which upon contact with water produces carbon dioxide, which will remove the paint from clothing. Godly '535 claims a paint composition, which comprises an extender (such as calcium carbonate) in the amount between 10 and 30% by weight. Within this extender range in Godly '535, diatomaceous silica is present in an amount ran
Collen IP
Colton Laurence P.
Marcheschi Michael
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