Prepaints and methods of preparing paints from the prepaints

Details Prepaints and methods of preparing paints from the prepaints Prepaints and methods of preparing paints from the prepaints

2001-02-16

2003-03-11

Sanders, Kriellion A. (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...

C524S430000, C524S432000, C524S247000, C524S284000, C524S417000, C524S445000, C524S493000

Reexamination Certificate

active

06531537

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to sets of prepaints methods of formulating paint lines using its sets of prepaints, useful paints, including as architectural coatings, industrial coatings, graphic art coatings, elastomeric coatings and non-cementitious, aggregate finish coatings, from sets of prepaint compositions.
2. Description of Related Art
For decades, professional painters/contractors and do-it-yourself consumers have been able to purchase paints that are tinted at the point-of-sale rather than at the manufacturing facility. This postponement of product differentiation permits the buyer to specify the desired color of the paint from a wide variety of choices rather than a limited number of colors once produced by the paint manufacturer.
While not practiced commercially, it is also theoretically known in the paint industry to postpone product differentiation of the paint components themselves as long as possible in the paint manufacturing process. See, for example, Carola Grundfelt-Forsius' paper in
Faerg Lack Scand
43(2), pages 5-6 (1997) which describes the use of intermediaries or components, i. e., mixtures of several of the paint raw material ingredients, that are mixed together with the tinting pastes to yield different types of paints. Grundfelt-Forsius provides an example of such a system employing a polyurethane binder for a solution polymer system.
The methods of postponement of product differentiation offers the buyer the flexibility of selecting the desired final paints, whether it be the color of the paint or the type of paint while at the same time permitting the paint manufacturer or seller (retail or wholesale or distributor) to minimize inventories of raw materials, intermediates and final products as well as stock outages.
Despite these benefits, paint manufacturers have only been able to successfully employ the postponement in product differentiation to paint systems based on solution polymers. Paint manufacturers have not been successful in postponing product differentiation of paint components in latex polymer-based paint systems. Since the majority of paints used today are based on latex polymers, there is a need for a practical method for postponing product differentiation in a latex polymer-based paint system.
It is considerably more difficult to formulate a stable paint when using latex emulsion polymers rather than solution polymers because of latex instability. Emulsion polymers are very sensitive to the solvents and surface active agents commonly found in paint formulations, such as surfactants, dispersants, rheology modifiers, and co-solvents. Solution polymers are by definition soluble in the solvent they are supplied in, and there is no thermodynamic driving force causing the polymer molecules to agglomerate or become unstable. In contrast, latex polymers contain the polymeric material in particles that are insoluble in water. These particles require considerable surface modifications to render them stable when supplied in an aqueous medium. If the surface modification is inadequate, the latex particles attach to one another forming a coagulated mass which then separates out of the latex paint. Paint formulating with a latex system is very difficult because the surface active materials in the formulation disrupt the delicate balance of surface forces that stabilize the latex particles in a water medium.
The difference between latex polymer systems (also referred to herein as “emulsion”) and solution polymer systems is further explained in Temple C. Patton's book entitled
Paint Flow and Pigment Dispersion
(New York: John Wiley and Sons, Inc., 1979, pages 192-193). Here the author describes the drying processes for the two systems. The main difference lies in the time required for each polymer to reach an irreversible state. Latex polymers reach this state much faster than solution polymers and thus make paints based on latex polymers more difficult to stabilize than paints based on solution polymers. In discussing “solvent-type coatings”, (which contain solution polymers) the author writes “ . . . the liquid vehicle flows rather than deforms around the pigment particles on drying. This flow assists the compaction process as the film shrinks because of loss of volatile solvent. Although the vehicle becomes more viscous as solvent evaporates, flow persists through most of the drying cycle.” As the author paints out, the solution polymer is able to flow though most of the drying cycle as the solvent evaporates. This is not time for polymer emulsion. The same author notes: “ . . . there is a preliminary flow of the latex suspension. This takes place before the time when the latex particles are first forced to come into intimate contact because of initial water loss. However, after this relatively short but very important initial flow, pigment compaction to achieve a high critical pigment volume concentration (CPVC) is achieved mainly by plastic deformation and coalescence of the latex particles.” Coalescence is the irreversible contact between latex particles. Such irreversible contact can occur in a liquid paint based on latex polymers, but not in a liquid paint based on solution polymers. Thus, paints based on latex polymers are more difficult to formulate.
There is a great need to develop a set of prepaints and a method of formulating paints based on latex polymers using sets of prepaints.
Paint formulating involves the process of selecting and admixing appropriate paint ingredients in the correct proportions to provide a paint with specific processing and handling properties, as well as a final dry paint film with the desired properties. The major ingredients of latex paint formulations are a binder, an opacifying pigment, optional pigment extenders, and water. Common optional additives include defoamers, coalescents, plasticizers, thickeners, non-thickening rheology modifiers, opacifying agents, driers, anti-skinning agents, surfactants, mildewcides, biocides and dispersants. After the latex paint is formulated and applied to a surface, the paint dries by evaporation of the water, with or without the application of heat, and the binder forms a film containing therein the pigment and the pigment extender particles, if any.
Formulating paints is complex—it is not simply a matter of mixing a few paint ingredients in different ratios. Rather, it involves the selection and mixing of different paint ingredients in different ratios depending on the type of paint desired. This requires paint manufacturers to store many different paint ingredients and change paint ingredients during manufacture depending on the specific paint type being prepared.
Furthermore, it requires those in the supply chain, especially the paint retailers, to carry a large inventory of paints in the warehouse and on the store shelves in order to offer a range of paints, such as various sheen levels, tint bases, paints for exterior use, paints for interior use, and paints of varying quality. It would be desirable to make paints, either at a relatively large-scale industrial plant or at a relatively smaller-scale, point-of-sale or point-of-use location using a limited number of paint ingredients to prepare all of these different paint formulations, thus, minimizing the number and type of paint ingredients needed to make a range of paints.
SUMMARY OF THE INVENTION
A “paint line”, as used herein, includes at least two different paints which offer dried film properties which differ materially from each other in at least one observable property such as sheen, outdoor durability or color depth. A paint line may include, for example, three paints the dried films of which have different sheen levels, two paints the dried films of which have suitable interior or exterior performance, or four paints the dried films of which offer different quality or performance levels such as may be evidenced, for example, by different levels of scrub resistance.
A paint line could, more particularly, include four different paints, the dried fi

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