Stable Nonaqueous Microparticle Dispersions Prepared From Aminoplast Resins

This example illustrates the preparation of a polyester melamine crosslinked microparticle dispersion.

A solution was prepared by mixing the following ingredients:

The above mixture was added to 1,496 grams of ISOPAR K (boiling range 177.degree. C. to 197.degree. C., commercially available from Exxon) and 2,550 grams of heptane (boiling range 94.degree. C. to 98.degree. C.). The total mixture was stirred vigorously to produce a mixture which was passed through a MICROFLUIDIZER.RTM. M 110 emulsifier at a pressure of 7,900 psi to produce an opaque, bluish-white emulsion. The emulsion was stirred at 75.degree. C. to 100.degree. C. for 10 hours under a stream of nitrogen while collecting distillate. Vacuum was applied for six hours at 85.degree. C to remove solvent and achieve a final total solids content of 63 percent.

This Example illustrates the preparation of a glycoluril-polyol nonaqueous microparticle dispersion.

A solution was prepared by stirring together the following ingredients:

The solution was added to a stirring mixture of Isopar K (aliphatic solvent from Exxon having boiling point range of 177.degree. C. to 197.degree. C.) and 3750g heptane (boiling point range of 94.degree. C. to 98.degree. C.). The resulting mixture was passed through a MICROFLUIDIZER.RTM. M 110 emulsifier to produce a stable, bluish-white emulsion which was then heated at 70.degree. C. to 80.degree. C. for five hours under a nitrogen sparge. Of 1387 ml of distillate collected, 481 ml separated into a lower layer. The emulsion was further condensed by vacuum distillation at 50.degree. C to a total solids content of 51.8 percent. The Brookfield viscosity of the final emulsion was 124 centipoise at 50 rpm using a number 3 spindle. The dispersion exhibited an increase in viscosity upon standing undisturbed for several days however upon application of high shear the viscosity decreased.

This Example illustrates the preparation of a benzoguanamine polyol nonaqueous microparticle dispersion.

A solution was prepared by mixing the following ingredients:

The above solution was added while stirring to 250g of ISOPAR G (aliphatic solvent with a boiling range of 156.degree. C. to 176.degree. C., available from Exxon) and 500g heptane (boiling range of 94.degree. C. to 98.degree. C.) and then passed through a MICROFLUIDIZER.RTM. M 110 emulsifier at 9900 psi. The resulting emulsion was then heated at 60.degree. C. for three hours and at 80.degree. C. for an additional three hours under a nitrogen sparge that removed the alcohols being liberated. The emulsion was vacuum stripped to a final total solids content of 62.5 percent. The Brookfield viscosity at 50 rpm using a number 3 spindle was 138 centipoise. The mean particle size, as measured on a Coulter N4 particle size analyzer was 341 nanometers (0.341 micron) with a standard deviation of 88 nanometers (0.088 micron).

This example illustrates the preparation of a nonaqueous microparticle dispersion of the self-condensation polymeric product of a urea-formaldehyde condensate.

A solution of the following ingredients was prepared:

The above solution was added while stirring to 350g ISOPAR G (aliphatic solvent with a boiling range of 156.degree. C. to 176.degree. C., available from Exxon) and 700g heptane (boiling range 94.degree. C. to 98.degree. C.) and then passed through a MICROFLUIDIZER.RTM. M-110 emulsifier at 8100 psi. The resulting emulsion was heated at 80.degree. C. to 90.degree. C. for 9 hours under a stream of nitrogen. The total amount of distillate collected was 450 ml with 104 ml in the bottom layer. The final total solids content was 48.9 percent and the Brookfield viscosity using a number 1 spindle at 50 rpm was 22.4 centipoise. The mean particle size, as measured on a Coulter N4 particle size analyzer, was 331 nanometers (0.331 micron) with a standard deviation of 86 nanometers (0.086 micron).