Patent Application
20080182927
The instant invention relates to using polyisobutenylsuccinic anhydrides and related compounds for dispersing various particles and nanoparticles. Reaction products of PIBSA with amines or alcohols are used in the metalworking industry to prepare water-in-oil emulsions useful as cutting fluids and in the oil industry in automotive additives as detergents to disperse carbon deposits.
Various dispersing agents are known in the art such as disclosed in US 2003/0032679, US 2004/0209782, WO 87/05924 and U.S. Pat. No. 5,266,081. The disclosure of the previously identified patents and patent applications is hereby incorporated by reference.
These dispersing agents typically employ relatively high levels of these agents in order to achieve stability and, as a result, rheological properties are often adversely affected. There is a need in this art for stable dispersions of nanoparticles and/or microparticles particles of metal oxides and/or particles that have an metal oxide surface that do not have these problems, and to methods for preparing these dispersions.
The instant invention solves problems associated with conventional dispersions by employing polyisobutenylsuccinic anhydrides (PIBSA) and related compounds as a dispersing agent. The instant invention relates to the discovery that PIBSAs are effective, surprisingly even at relatively low levels, as a dispersant for metal oxide particles including nanoparticles in a wide range of liquids. Examples of such liquids comprise at least one member selected from the group consisting of toluene, xylene, mineral spirits, hexanes, and phenoxyisopropanol. Without wishing to be bound by any theory or explanation, it is believed that for many metal oxide surfaces, including at least one of alumina, zinc oxide, ITO, zirconia or titania, the anhydride or diacid group serves as a good anchoring group. It is also believed that in other instances wherein other anchoring groups are more effective (such as mercaptans for noble metal surfaces), it is possible to use the reactive anhydride group to introduce alternate functionality. These PIBSA derivatives may also be used in combination with commercially available dispersant(s) to reduce overall dispersant loading.
One aspect of the instant invention relates to a composition comprising a dispersion of particles in at least one organic liquid. The composition comprises:
Or reactions products of this molecule such as those having structural formulas:
The inventive dispersion can be prepared by any suitable method such as ball mills, stirred bead mills, homogenizers, roll mills, and ultrasonication baths.
While the inventive dispersant can be used for dispersing a wide range of particles, nanoparticles of metal oxides, specifically, those of zinc, zirconium, cerium, titanium, aluminum, indium and tin, and mixtures thereof, are illustrative of nanoparticles having important commercial applications. Nano zirconia, ceria and alumina are useful for scratch resistant coatings and heat transfer fluids. Additionally, aluminum metal nanoparticles that have been passivated with a thin layer of aluminum oxide are useful in the development of energetic materials. Indium tin oxide (ITO) nanoparticles have applications in clear conductive coatings, in heat management layers, and in static charge dissipation. Zinc oxide and titania are useful for UV blocking applications, including sunscreens, textiles and coatings. Other applications of metal oxide particles, nanoparticles and/or nanoparticles that have a metal oxide surface include, for example, magnetic materials, heterogeneous catalysts, toner compositions, and ceramics.
In order to supply nanoparticles and/or microparticles as easy to use dispersion master batches or in fully formulated compositions, it is desirable for the particles to be dispersed in various liquids and polymeric matrices. The quality of the dispersion should be commensurate its intended use. For example, the presence of color is undesirable in many applications such as certain inks and coatings. In addition, the dispersion is typically stable so it does not have to be prepared immediately before use, but can be stored after preparation. Depending upon the application of a formulated composition, the inventive composition can comprise about 0.5 to about −90 wt. % of an ingredient of the formulated composition.
The inventive composition can be added to a wide range of polymeric matrices. This is most readily achieved by adding the inventive composition to a solution or dispersion of the polymer in an organic solvent. Examples of suitable polymers comprise at least one of polyacrylates, polysiloxanes, polyurethanes, polyesters, polyamides, polyvinyl chloride, polyisoprene, polychloroprene, poly(styrene-co-butadiene), polyepoxides, polyalkyds and among other polymers that can used in coatings, inks and adhesives.
The following Examples are provided to illustrate certain aspects of the instant invention and do not limit the scope the claims appended hereto.
The following materials were used to conduct the Examples below.
Example 1 was prepared by placing the sample containing 1.0 mm zirconia beads grinding media in a sonication bath for 6 hrs at 65 C. The solvent was mineral spirits. Example 2 was prepared in the same manner but 0.1 mm zirconia beads were used. The solvent was a high boiling (140-180 C) petroleum ether. The dispersions prepared in Examples 1 and 2 had relatively small particle sizes and exhibited only minor settling after several days.
The dispersions in Examples 3-5 were prepared by mixing the ZnO and dispersant with only enough solvent to yield a high solids (70-75%) paste. The paste was processed on a three-roll mill for five passes with a gap setting of 5 mils and a roll speed of 100 rpm. After milling, the pastes were diluted with the remainder of the solvent to produce the compositions shown in Table 2. The diluted dispersions had a relatively small particle size and exhibited only minor settling after several days.
Reaction products of PIBSA with either Ancamine 1637 Mannich Base or 4-aminosalicylic acid were prepared by refluxing the components shown in Examples 6-8 for four hours and then removing solvent at atmospheric pressure. The reaction products were used without further purification.
Table 4 illustrates the use of the reaction products from Table 3 as dispersants for alumina, zirconia and ceria nanoparticles.
Examples 9-16 were prepared by placing the samples in a sonication bath for 2 hrs at 65 C. The dispersions in Examples 9-13 which were prepared with the PIBSA reaction products were low viscosity fluids which did not exhibit sedimentation over several days. Example 14 shows that neat Ancamine 1637 produced a paste. A comparison of Examples 10 and 15 shows that reducing the dispersant level from 4.8 to 2.4 caused an increase in viscosity. Example 16 shows that a standard commercial dispersant is ineffective in dispersing nano alumina in toluene.
Table 5 compares the efficacy of dispersants to yield a low viscosity dispersion of nano alumina in an epoxy curing agent, PACM (bis-4-aminocylcohexylmethane). Both the reaction product from Ex. 6 and Ancamine 1637 give a lower viscosity than the commercial dispersant Disperbyk 163 and the control without dispersant.
Example 21-25 were prepared by placing the sample containing 0.05 mm zirconia beads grinding media in a sonication bath for 6 hrs at 65 C. The solvent was mineral spirits. The PIBSA was evaluated neat and in the presence of various amines. The dispersions prepared in Examples 21-25 had relatively small particle sizes and exhibited only minor settling after several weeks.
The invention has been described with reference to particular aspects or embodiments, but other embodiments are apparent to persons of skill in the art, and are included within the scope of the claims.
This Application claims the benefit of Provisional Application No. 60/898,555, filed Jan. 31, 2007. The disclosure of this Application is hereby incorporated by reference. The subject matter of the instant invention is related to the following U.S. patent application Ser. Nos. 11/583,439, 11/524,471 and ______, filed on even date herewith an entitled “Hydrophobic Metal And Metal Oxide Particles With Unique Optical Properties”. The disclosure of these patent applications is hereby incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| 60898555 | Jan 2007 | US |
