Polymer dispersed cellulose nanocrystals

Abstract

The present invention relates to a dispersion of cellulosic nanocrystals (CNCs) that is capable of reflecting/scattering UV radiation. A very specific class of polyesters have found to be effective in making reflective dispersions that can range over a very wide range of radiation, including IR and UV. The resulting dispersion, when applied to the skin or surface, can provide protection from the UV rays of the sun.

Claims

1. A cellulose nanocrystal dispersion comprising: a. 0.1 to 12% wt/wt of cellulose nanocrystals selected from the group consisting of cellulose nanocrystals functionalized with the following; sodium sulfate half ester, carboxylated, imidazolium salts; hexyl imidazolium salts, methyl imidazolium salts, imidazolium salts, imidazolium chloride, phosphonium salts, ammonium salts, cellulose nano-fibers and plant based cellulose, cellulose nano-fibers, and plant based cellulose nanocrystals and mixtures thereof: and b. 88.0-99.9% by weight of a polyester made by the reaction of: 1. Guerbet alcohol having the following structure: ##STR00009## y is an integer ranging from 3-15; x is an integer ranging from 5-17; 2. 1,3 propanediol having the following structure: ##STR00010## 3. a diacid selected from the group consisting of: ##STR00011## and a hydrogenated dimer acid having the following structure: ##STR00012## and mixtures thereof, wherein the resulting dispersion reflects/scatters 240-400 nm light.

2. A cellulose nanocrystal dispersion of claim 1, which comprises between 0.1 to 12% by weight sodium sulfate half ester CNCs with a polyester where in: x is 9, y is 7, and diacid is hydrogenated dimer acid.

3. A cellulose nanocrystal dispersion of claim 1, which comprises between 0.1 to 12% by weight sodium sulfate half ester CNCs with a polyester where in: x is 13, y is 11, and diacid is hydrogenated dimer acid.

4. A cellulose nanocrystal dispersion of claim 1, which comprises between 0.1 to 12% by weight of plant based cellulose nano-crystals with a polyester where in: x is 9, y is 7, and diacid is hydrogenated dimer acid.

5. A cellulose nanocrystal dispersion of claim 1, which comprises between 0.1 to 12% by weight of plant based cellulose nano-crystals with a polyester where in: x is 13, y is 11, and diacid is hydrogenated dimer acid.

6. A process for protecting skin from UV radiation which comprises contacting skin with an effective UV reflecting or scattering dispersion of polymer dispersed cellulose nanocrystals prepared by mixing: a. a cellulose nanocrystal selected from the group consisting of cellulose nanocrystals functionalized with the following: sodium sulfate half ester, carboxylated, imidazolium salts, hexyl imidazolium salts, methyl imidazolium salts, imidizolum chloride, phosphonium salts, ammonium salts, cellulose nano-fibers and plant based cellulose nano-crystals and mixtures thereof; and b. a polyester made by the reaction of: 1. a Guerbet alcohol having the following structure: ##STR00013## wherein: y is an integer ranging from 3-15; x is an integer ranging from 5-17; and mixtures thereof; and 2. a propane diol having the following structure: ##STR00014## 3. a diacid selected from the group consisting of: ##STR00015## and a hydrogenated dimer acid having the following structure: ##STR00016## and mixtures thereof.

7. A process of claim 6, which comprises between 0. 1 to 12.0% by weight of sodium sulfate half ester CNCs with a polyester wherein: x is 9 and y is 7, and diacid is hydrogenated dimer acid.

8. A process of claim 6, which comprises between 0. 1 to 12.0% by weight of sodium sulfate half ester CNCs with a polyester wherein: x is 13 and y is 11, and diacid is hydrogenated dimer acid.

9. A process of claim 6, which comprises between 0.1 to 12.0% by weight of plant based cellulose nano-crystals with a polyester wherein: x is 9 and y is 7, and diacid is hydrogenated dimer acid.

10. A process of claim 6, which comprises between 0.1 to 12.0% by weight of plant based cellulose nano-crystals with a polyester wherein: x is 13 and y is 11, and diacid is hydrogenated dimer acid.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a line graph showing the absorption versus wavelength of examples 8-11. The absorbance is plotted on the y-axis and wavelength in nanometers is plotted on the x-axis.

(2) FIG. 2 is a line graph showing the absorption versus wavelength of examples 26-29. The absorbance is plotted on the y-axis and wavelength in nanometers is plotted on the x-axis.

(3) FIG. 3 is a line graph showing the absorption versus wavelength of examples 30-32 and poly(hydroxystearic acid). The absorbance is plotted on the y-axis and wavelength in nanometers is plotted on the x-axis.

DETAILED DESCRIPTION OF THE DRAWINGS

(4) FIG. 1 shows the absorption spectra of examples 8-11 taken on a Shimatzu UV-VIS instrument. The figure shows a strong absorbance from 280-800 nm for examples 8-11. The figure also shows that the more CNCs in the dispersion, the higher the absorption.

(5) FIG. 2 shows the absorption versus wavelength of examples 26-29 taken on a Shimatzu UV-VIS instrument. The figure shows a strong absorbance from 280-800 nm with the strongest absorption occurring at 306 nm. FIG. 2 also shows that the absorption increases as the amount of CNCs is increased.

(6) FIG. 3 shows the absorption versus wavelength of examples 30-32 taken on a Shimatzu UV-VIS instrument. The figure shows a strong absorbance from 280-800 nm with the strongest absorption occurring at 306 nm. Also shown in the figure is a comparison of the dispersions of the current invention and the most commonly used dispersion agent in the personal care market, poly(hydroxy stearic acid). As seen in the figure, the dispersion of the current invention surprisingly and unexpectedly has a absorption from 280 nm to 800 nm, meanwhile the absorption of the dispersion in poly(hydroxy stearic acid) show an absorption at 250 nm, but a zero absorption from 280 nm to 500 nm.