Compositions: coating or plastic – Materials or ingredients – Pigment – filler – or aggregate compositions – e.g. – stone,...
Reexamination Certificate
2000-06-02
2003-08-19
Anthony, Joseph D. (Department: 1714)
Compositions: coating or plastic
Materials or ingredients
Pigment, filler, or aggregate compositions, e.g., stone,...
C106S447000, C106S476000, C516S032000, C516S033000, C252S182230
Reexamination Certificate
active
06607591
ABSTRACT:
1. Field of the Invention
This invention relates to new and useful nonaqueous liquid pigment dispersions which are easy to handle and produce thorough and effective colorations within target media, particularly as compared to standard solid pigments or high-viscosity liquid pigment dispersions. More specifically, the present invention relates to liquid pigment dispersions possessing viscosities of at most 5,000 centipoise at standard temperature and pressure. Such a low viscosity is obtained through the addition of relatively low amounts of aprotic viscosity modifiers possessing dipole moments of between about 1.0 and 5.0, or, alternatively, a flash point of between about −20° C. and 180° C., such as, most preferably, cyclic carbonates. The resultant low-viscosity pigment compositions thus can be incorporated into any standard coloring method utilizing pigments (such as, for example, for polyurethanes, polyolefins, and the like) without the problems associated with traditionally utilized solid or thickened, high viscosity pigment materials. The method of coloring such target media is also encompassed within this invention.
2. Background of the Prior Art
Polyurethane products, such as foams, resins, and the like, have traditionally been colored by pigments, polymeric colorants, and dyes. Generally, these colorations are performed in situ during foam, resin, etc., formation. For instance, polymeric colorants (i.e., polyoxyalkylenated colorants), such as those described in U.S. Pat. No. 4,284,279 to Cross et al., have been introduced within polyol compositions during slabstock foam production. The “colored” polyol then reacts with an isocyanate composition, in the presence of a catalyst possibly, to form the desired colored foam. Pigments have also been added in the past, most notably in solid, paste, or powder form, to a polyol stream to form the same type of colored foam products. Such compounds are readily available and inexpensive; however, they also exhibit or create problems during handling, mixing (with other pigments to create different shades, for example), and actual incorporation within target media. Furthermore, pigments, being solid in nature, tend to from clumps of solids within target media that leads to aesthetically displeasing consequences or clogging of machinery or instrumentation (such as pumps, valves, injectors, and the like). Additionally, spills are likely (since the powder or solid form of such pigments do not transport easily due to atmospheric conditions and possible air disturbances), and clothes or hand staining by difficult-to-handle pigment compounds is very likely to occur through the utilization of such solid coloring agents. As such, there is a need to improve upon these handling deficiencies of standard solid and powder pigments compounds. Polymeric colorants, being liquid in nature, have proven easier to use in such processes due to facilitation of handling, particularly at industrial levels. Low viscosity dispersions of pigments with low color availability have been developed within this industry as an attempt to alleviate such handling problems (and thus permit utilization of polymeric colorant-like liquid compositions). However, such low viscosity dispersions are not storage stable and have precipitation problems that produce uneven colorations within the final polyurethane product and thus make such dispersions unsuitable for large-scale industrial use as well. Traditionally, a trade-off has been present with pigments: the higher the viscosity of the pigment solution, the better the storage stability; the lower the viscosity, the worse the storage stability. As such, there is a recognized need to provide an improved pigment dispersion that possesses long-term storage stability as well as good colorability of the target polyurethane composition. Furthermore, such dispersions should exhibit the shade general degree of color depth within the target article substrate as a standard pigment provides. To date, there have existed no such needed advancements in this art.
OBJECTS OF THE INVENTION
It is therefore an object of this invention to provide a substantially uniform, low viscosity liquid pigment dispersion for ease of handling in large industrial applications. A further object is to provide a liquid pigment dispersion for utilization within a colored foam production process. A further objective of this invention is to provide a storage-stable pigment dispersion that retains the same general color value as the non-dispersed pigment.
SUMMARY OF THE INVENTION
Accordingly, this invention is directed to a nonaqueous liquid dispersion comprising at least one pigment and at least one aprotic viscosity modifying compound exhibiting a dipole moment of between about 1.0 and 5.0 or alternatively, a flash point of between about −20° C. and 180° C. Also encompassed within this invention is a method of producing a colored polyurethane comprising the steps of
(a) providing a polyol composition;
(b) introducing a nonaqueous liquid dispersion comprising at least one pigment and at least one aprotic viscosity modifying compound exhibiting a dipole moment of at least 1.0. into said polyol composition to form a colored polyol composition; and
(c) mixing said colored polyol composition with an isocyanate to form a polyurethane.
The term “nonaqueous” denotes a composition into which no water has been specfically introduced. Due to the possibility of atmospheric water being introduced through exposure to a relatively humid environment, this term does not rule out the potential for any water to be present through such a manner. The term “liquid dispersion” is intended to encompass any composition which is present in a fluid state (i.e., possessing a viscosity of below about 10,000 centipoise at standard temperature and pressure). The term “aprotic” is well known within the chemical arts and simply means that no protons can be accepted or donated by the specific compound. As such, it is imperative that certain moieties not be present on the intended viscosity modifying compound. Such unwanted moieties include, without limitation, acid groups, hydroxyls, amines, and the like.. However, as noted above, this list is not definitive; any aprotic compound possessing the required dipole moment or flash point is included in this definition.
The dipole moment requirement for the viscosity modifying compound is necessary to provide the desired performance characteristics for the inventive nonaqueous pigment-containing dispersion. It has been found, surprisingly, that the selection of a relatively low dipole moment viscosity modifying compound provides the desired drastic lowering of overall viscosity while simultaneously separating individual pigment particles within solution, and preventing reagglomeration of the same particles. Furthermore, due to the low dipole moment, the corresponding flash point of the viscosity modifying compound is also relatively low in order to permit removal of such a compound upon introduction within a coloring method utilizing relatively low processing temperatures, if desired. Alternatively, such compounds may also react within the target media as well. As such, since the aprotic compound must exhibit a low flash point, and dipole moments have not been recorded for all compounds which may function in this capacity within the inventive dispersions, the viscosity modifying compound may alternatively be defined in relation to its aprotic nature and its flash point. Thus, a flash point of between about −20° C. and 180° C. is necessary; preferably such a level is between 0° C. and 165° C.; more preferably from 80° C. to about 160° C.; most preferably between about 95° C. and 145° C. Such an aprotic compound thus does not affect any production methods (such as, as merely one example, polyurethane coloring through initial introduction within a polyol composition followed by admixing with an isocyanate; at low heat exposures, the viscosity modifying compound will evaporate from the final composition with relative ease). It is also pre
Ragsdale Mark E.
Stephens Eric B.
Xia Jusong
Anthony Joseph D.
Milliken & Company
Moyer Terry T.
Parks William S.
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