Treatment composition with delivery particles made from acid-treated chitosan
A treatment composition that includes a treatment adjunct and a population of core/shell delivery particles, where the shell is made from an acid-treated chitosan and a cross-linking agent, where the acid-treated chitosan results from treating chitosan with a weak acid, or even a mixture of a strong acid and a weak acid. Related methods of making and using such compositions.
1 . A treatment composition comprising a treatment adjunct and a population of delivery particles,
wherein the delivery particles comprise a core and shell surrounding the core,
wherein the core comprises a benefit agent,
wherein the benefit agent comprises a fragrance material,
wherein the shell consists of a polymeric material that is a reaction product of an acid-treated chitosan and at least one cross-linking agent,
wherein the acid-treated chitosan results from treating chitosan with a mixture of a first acid and a second acid,
the first acid is a strong acid,
the second acid is a weak acid,
wherein the first acid and the second acid are present in a normality ratio of from about 35:65 to about 65:35,
wherein the chitosan is treated with the mixture at a pH of 6.5 or less, and at a temperature of at least 25° C.,
wherein the at least one cross-linking agent is polyisocyanate, and
wherein the treatment adjunct comprises a conditioning active.
2 . The treatment composition according to claim 1 , wherein the first acid is selected from the group consisting of hydrochloric acid, perchloric acid, nitric acid, sulfuric acid, and a mixture thereof.
3 . The treatment composition according to claim 1 , wherein the second acid is selected from the group consisting of formic acid, acetic acid, ascorbic acid, glutamic acid, lactic acid, maleic acid, malic acid, succinic acid, citric acid, acrylic acid, oxalic acid, tartaric acid, and a mixture thereof.
4 . The treatment composition according to claim 1 ,
wherein the first acid has a first pKa of less than 1, and
the second acid has a first pKa of from about 1 to about 5.5.
5 . The treatment composition according to claim 1 , wherein the chitosan is characterized by a weight average molecular weight of from about 100 kDa to about 600 kDa.
6 . The treatment composition according to claim 1 , wherein the reaction product is formed in a reaction, wherein the weight ratio of the chitosan present in the reaction to the cross-linker present in the reaction is from about 1:10 to about 1:0.1.
7 . The treatment composition according to claim 1 , wherein the fragrance material comprises perfume raw materials characterized by a logP of from about 2.5 to about 4.5.
8 . The treatment composition according to claim 1 , wherein the core further comprises a partitioning modifier.
9 . The treatment composition according to claim 1 , wherein the delivery particles are characterized by a volume-weighted median particle size from about 1 to about 100 microns.
10 . The treatment composition according to claim 1 , wherein the delivery particles are obtainable from a process comprising the steps of:
forming a water phase by treating the chitosan with the mixture of the first acid and the second acid,
wherein the chitosan is treated at a pH of 6.5 or less, and at a temperature of at least 25° C., for at least one hour, thereby forming an acid-treated chitosan;
forming an oil phase, the forming step comprising dissolving together the benefit agent and the at least one cross-linking agent;
forming an emulsion by mixing the oil phase into an excess of the water phase, thereby forming droplets of the oil phase dispersed in the water phase, and optionally adjusting the pH of the emulsion to be in a range from pH 2 to pH 6;
curing the emulsion at a temperature of at least 40° C. for a time sufficient to form a shell at an interface of the droplets with the water phase,
the shell consisting of the reaction product of the at least one cross-linking agent and the acid-treated chitosan, and
the shell surrounding the core comprising the droplets of the oil phase.
11 . The treatment composition according to claim 1 , wherein the delivery particles are cationic and characterized by a zeta potential of at least 15 mV at a pH of 4.5.
12 . The treatment composition according to claim 1 , wherein the shells of the delivery particles degrade at least 60% in 60 days when tested according to test method OECD 301B.
13 . The treatment composition according to claim 1 , wherein the treatment adjunct further cmprises surfactants, deposition aids, rheology modifiers or structurants, bleach systems, stabilizers, builders, chelating agents, dye transfer inhibiting agents, dispersants, enzymes, enzyme stabilizers, catalytic metal complexes, polymeric dispersing agents, clay and soil removal/anti-redeposition agents, brighteners, suds suppressors, silicones, hueing agents, aesthetic dyes, neat perfume, additional perfume delivery systems, structure elasticizing agents, carriers, hydrotropes, processing aids, anti-agglomeration agents, coatings, formaldehyde scavengers, pigments, or mixtures thereof.
14 . The treatment composition according to claim 1 , wherein the treatment adjunct further comprises anionic surfactant, a cationic conditioning agent, or a mixture thereof.