Crosslinked polysaccharides and methods of production thereof
View Patent ↗A substantially boron-free method for making a cationic guar comprises reacting particles of polysaccharide with a derivatizing agent to produce derivatized polysaccharide particles, washing the derivatized polysaccharide particles, and contacting, prior to or after the washing step, the particles with a glyoxal compound in order to crosslink the derivatized polysaccharide particles. Also disclosed are methods for making crosslinked derivatized polysaccharides, comprising (a) contacting particles of a polysaccharide with a titanium compound in an aqueous medium having an alkaline pH under conditions appropriate to intra-particulately crosslink the particles; (b) reacting, prior to or after the step of contacting the particles of polysaccharide with the titanium compound, the particles of polysaccharide with a derivatizing agent under conditions appropriate to produce derivatized polysaccharide particles; (c) washing the titanium crosslinked and derivatized particles; (d) contacting, concurrently with or after the step of washing the titanium crosslinked and derivatized particles, such particles with an aqueous medium having an acidic pH under conditions appropriate to substantially de-crosslink the particles; and (e) contacting, concurrently with or after step (d), the de-crosslinked particles with a glyoxal compound under conditions appropriate to intra-particulately crosslink the particles. The crosslinked cationic guar of the present invention is especially useful in home and personal care formulations, especially formulations comprising silicone since it improves silicone deposition.
1. A method for producing crosslinked derivatized polysaccharides, comprising:
(a) contacting particles of a polysaccharide with a titanium compound in an aqueous medium having an alkaline pH under conditions appropriate to intra-particulately crosslink the particles;
(b) reacting, prior to or after the step of contacting the particles of polysaccharide with the titanium compound, the particles of polysaccharide with a derivatizing agent under conditions appropriate to produce derivatized polysaccharide particles;
(c) washing the titanium crosslinked and derivatized particles;
(d) contacting, concurrently with or after the step of washing the titanium crosslinked and derivatized particles, such particles with an aqueous medium having an acidic pH under conditions appropriate to substantially de-crosslink the particles; and
(e) contacting, concurrently with or after step (d), the de-crosslinked particles with a glyoxal compound under conditions appropriate to intra-particulately crosslink the particles.
2. The method of claim 1 wherein the titanium compound is selected from the group consisting of titanium salts, titanium chelates and titanium esters.
3. The method of 1 wherein the titanium compound is selected from the group consisting of titanium tetrachloride, titanium tetrabromide, tetra amino titanate, titanium acetylacetonate, triethanolamine titanate, titanium lactate, n-butyl polytitanate, titanium tetrapropanolate, octyleneglycol titanate, tetra-n-butyl titanate, tetra-2-ethylhexyl titillate, tetra-isopropyl titanate, diisopropyl di-triethanolamino titanate, titanium ortho ester, titanium (IV) chloride and mixtures thereof.
4. The method of claim 1 wherein contacting the titanium crosslinked and derivatized particles with an aqueous medium in step (d), contacting the de-crosslinked particles with a glyoxal compound in step (e) or both is performed through a spraying process.
5. The method of claim 1 wherein about 0.01 to about 30 parts by weight of the glyoxal compound per 100 parts by weight of the derivatized polysaccharide particles is utilized to intra-particulately crosslink the particles.
6. The method of claim 5 wherein about 0.1 to about 30 parts by weight of the glyoxal compound per 100 parts by weight of the derivatized polysaccharide particles is utilized to intra-particulately crosslink the particles.
7. The method of claim 1 wherein the contacting of particles of polysaccharide with the titanium compound in step (a) occurs after the reacting of the particles of polysaccharide with the derivatizing agent in step (b).
8. The method of claim 1 wherein the aqueous medium having an acidic pH comprises a Bronsted acid.
9. The method of claim 8 wherein the Bronsted acid is citric acid.
10. The method of claim 1 wherein the derivatized polysaccharide particle is a derivatized guar particle.
11. The method of claim 10 wherein the derivatized guar particle is selected from the group consisting of hydroxypropyl guar, carboxymethyl guar, hydroxyethyl guar, carboxymethylhydroxypropyl guar, hydroxybutyl guar, cationic guar, hydrophobically modified guar, hydrophobically modified carboxymethyl guar, hydrophobically modified hydroxyethyl guar, hydrophobically modified hydroxypropyl guar, hydrophobically modified carboxymethylhydroxypropyl guar, hydrophobically modified hydroxybutyl guar, and hydrophobically modified cationic guar.
12. The method of claim 1 further comprising:
(f) washing the glyoxal crosslinked and derivatized particles concurrently with or after step (e).
13. The method of claim 1 wherein the step of contacting particles of a polysaccharide with a titanium compound is conducted in an aqueous medium having a pH greater than 10 under conditions appropriate to intra-particulately crosslink the particles.
14. The method of claim 13 wherein the step (e) comprises contacting the de-crosslinked particles with a glyoxal compound in an aqueous medium having a pH less than 7 under conditions appropriate to intra-particulately crosslink the particles.
15. The method of claim 13 wherein contacting the titanium crosslinked and derivatized particles with an aqueous medium in step (d), contacting the de-crosslinked particles with a glyoxal compound in step (e) or both is performed through spraying.