Method for producing shaped functional cellulose articles with targeted release of active ingredients

Abstract

Methods for producing cellulose articles having controlled release of active ingredient include dispersing pulp in aqueous direct solvent for cellulose to form a slurry. Organically modified or ion-exchange-activated phyllosilicate is homogenized in a direct solvent for cellulose with exfoliation by shearing, then mixed with the slurried pulp. A mixture of active ingredient and a lipophilic matrix material or a water-in-oil (“W/O”) emulsion containing active ingredient is stabilized with thickener, converted into a gel-like paste, and mixed with the slurried pulp. Water is stripped from the mixture until all cellulose is dissolved, the mixture is formed into shaped articles, and dried. Exemplary active ingredients include cosmetic active ingredients, fat-soluble vitamins or apolar plant extracts. Domains of active ingredient and matrix material or emulsion containing active ingredient are present as fine divisions within the inventive articles. Exemplary shaped articles include functional fibers in knitted, woven and nonwoven fabrics; paper; foils and membranes.

Claims

1. A method of producing shaped cellulosic articles featuring controlled release of an active ingredient, said method comprising the stages: a) dispersing pulp in an aqueous direct solvent for cellulose to form a cellulose furnish, b) adding, in a separate step of the method, a nanoscale sheet-silicate, optionally organomodified, or preactivated by ion exchange with potassium, calcium or aluminium ions that has been homogenized with an aqueous direct solvent for cellulose and exfoliated fully or partially by the size of the intercalated compounds, the amount of intercalated water, as well as by defined adjusting the length of time and the rate of shearing, to the cellulose furnish and mixed therewith, c) adding, in a further separate step of the method, a composition of an active ingredient and a lipophilic matrix material which contains the active ingredient or an active-containing water-in-oil emulsion stabilized by organic or inorganic thickeners and converted into a gel-like paste, this paste likewise being added to the cellulose furnish and mixed at temperatures up to 130° C. therewith under agitation, d) adding water after the mixing in step c) to completely dissolve the cellulose and form a spinning solution, and e) shaping the resultant spinning solution by a solution-spinning process into shaped articles, aftertreating, optionally spin finishing and drying.

2. The method as claimed in claim 1, wherein the direct solvent tor cellulose is an aqueous N-methylmorpholine N-oxide solution, a water-containing ionic liquid, which may further contain organic solvents, or a solution of dimethylacetamide (DMAc) and lithium chloride.

3. The method as claimed in claim 1, wherein the organomodified sheet-silicates are synthetic sheet-silicates modified by ammonium cations having at least one long-chain unbranched alkyl and/or alkenyl moiety of 14 or more carbon atoms, wherein the alkyl or alkenyl moiety may be substituted.

4. The method as claimed in claim 1, wherein the organo-modified sheet-silicate(s) is present in the shaped cellulosic articles in a proportion of from 0.5 to 20 wt %, based on the weight of cellulose.

5. The method as claimed in claim 1, wherein the active ingredient is selected from the group of solid or liquid lipophilic actives.

6. The method as claimed in claim 1, wherein the lipophilic matrix material for the active ingredient is a hydrocarbon having more than 8 carbon atoms.

7. The method as claimed in claim 1, wherein the inorganic thickeners are nanoparticles of fumed silica, metal oxide ceramic and/or metal.

8. The method as claimed in claim 1, wherein the organic thickeners are aliphatic-aromatic block copolymers.

9. The method as claimed in claim 1, wherein the composition of active ingredient and lipophilic material is present in concentrations of 0.1 to 200 g per kilogram of cellulose.

10. The method as claimed in claim 9, wherein the water-in-oil emulsion comprises, dispersed in an oily phase, a hydrophilic phase, each mixed with apolar hydrocarbons, fatty alcohols, fatty acids and fatty acid esters having more than 8 carbon atoms and natural or synthetic emulsifiers, wherein the concentrations of the aqueous components is from 0.1 to 200 g per kilogram of liquid phase.

11. The method as claimed in claim 1, wherein the release of the active ingredients is controlled by the degree of exfoliation of the sheet-silicates, by the chemical structure and the concentration of the cations in the sheet-silicate, by the temperature daring the preswelling of the organomodified sheet-silicate and/or during the production of the paste of active ingredient and lipophilic material for the active ingredient, by the viscosity of the dispersant used therein, by the water content therein, by the nature of the lipophilic matrix material arid also the intensity and duration of the mixing/shearing of the organomodified sheet-silicates.

12. The method as claimed in claim 1, wherein the inorganic nanoparticles are present in a proportion of 0.1 to 10 wt %, based on the total weight of the mixture of active ingredient and lipophilic material for the active ingredient.

13. The method as claimed in claim 1, wherein the spinning solution has a shear thinning exponent n in the range from 0.0 to −1.2.

14. A shaped cellulosic article having finely dispersed therein domains of compositions of active ingredients and lipophilic matrix materials for the active ingredients or active-containing water-in-oil emulsions, obtained by a method as claimed in claim 1, wherein the organomodified sheet-silicates are modified by ammonium or phosphonium cations having at least one straight-chain hydrocarbon moiety of 14 or more carbon atoms.

15. The shaped cellulosic article as claimed in claim 14, wherein said shaped cellulosic article is incorporated into textile applications and is reloadable with highly volatile, thermally and/or chemically sensitive active ingredients.

16. The shaped cellulosic articles as claimed in claim 14 as functional fiber in blend yams with polyester fibers, polyamide fibers, polypropylene fibers, viscose fibers, cotton fibers or wool, in textile knits and wovens, in nonwoven and nonwoven composites, in paper and paper composites, and also in foils and membranes.

17. The method as claimed in claim 3, wherein the alkyl and/or alkenyl moiety has 14 to 20 carbon atoms and may be substituted with one or more hydroxyl or carboxyl groups.

18. The method as claimed in claim 4, wherein the shaped cellulosic articles are functionalized cellulosic fibers, and the organo-modified sheet-silicate(s) is present in a proportion of from 5 to 15 wt %, based on the weight of cellulose.

19. The method as claimed in claim 5, wherein the active ingredient is an active cosmetic ingredients selected from evening primrose oil, St John's wort oil, jojoba oil, avocado oil, fat-soluble vitamins and provitamins, W/O emulsions or apolar or aqueous plant extracts.

20. The method as claimed in claim 19, wherein the fat-soluble vitamins and provitamins are vitamin A, retinol, vitamin D or vitamin E.

21. The method as claimed in claim 6, wherein the hydrocarbon has 8 to 22 carbon atoms and is a (C8-C22)fatty alcohol, a (C8-C22)fatty acid and/or a fatty acid ester having 8 to 22 carbon atoms in the fatty acid portion.

22. The method as claimed in claim 10, wherein the hydrophilic phase is an aqueous preparation of active cosmetic ingredients or aqueous extracts of plant ingredients.

23. The method as claimed in claim 13, wherein the shear thinning exponent n is in the range from −0.1 to −1.0.

24. The shaped cellulosic article as claimed in claim 14, wherein the organo-modified sheet-silicates are modified by ammonium or phosphonium cations having at least one straight-chain hydrocarbon moiety of 14 to 20 carbon atoms.

Description

EXAMPLES

[0051] The examples which follow illustrate the invention. They set forth possible embodiments of the method according to the invention without any claim to exclusiveness. Percentages are by mass unless otherwise stated.

Example 1

[0052] 2.265 kg of cotton linters pulp (DP; 618) and 114 g of propyl gallate are mixed with 21.000 kg of a 60% aqueous NMMO solution and the mixture is sent to a stirred tank. Under agitation by stirring at 50 min.sup.−1 the furnish is stripped of about 5 l of water in a vacuum of 40 mbar and at a temperature of 50° C. Concurrently, by Ultra Turrax shearing for 30 min at 25 000 min.sup.−1, 2.242 kg of an 80% aqueous NMMO solution and 364.5 g of sheet-silicate (montmorillonite modified with methyl-tallow-bis(2-hydroxyethyl)ammonium—cations naturally present in montmorillonite have been exchanged for these ammonium cations=Cloisite® 30 B Nanoclay from Southern Clay) are dispersed and added to the furnish. The furnish batch is further stirred at 50 min.sup.−1, 100° C. in a vacuum of 20 mbar until a highly viscous mass is formed. The highly viscous mass then has added to it a dispersion of 135 g of evening primrose oil, 545 g of n-octadecane and 91.1 g of fumed silica (Aerosil® R 106), the dispersion having been fabricated separately under severe UltraTurrax shearing, and the entire mixture is further stirred at 100° C. and 20 mbar until homogeneous distribution has been achieved for ail components. The shear thinning exponent was determined as −0.86 (curve d) in FIG. 1). After the final spinning dope has been transferred, a dry-wet spinning process (120 μm die orifices, 20 mm air gap) is used to fabricate staple fibers having a fineness of 2.2 dtex and 60 mm cut length.

[0053] 1500 g of the staple fibers thus fabricated are blended with 3500 g of cotton fibers, the blend is passed through a laboratory card, cross-lapped and needled into a web having a basis weight of 150 g/m.sup.2.

[0054] To measure the transfer of active ingredient out of the textile fabric onto a technical model of skin, at 25° C. and 60% humidity due to mechanical stress, a rub abrasion tester was used to carry out an actual-wear simulation test in line with DIN EN ISO 105-X12 2002-12. The transferred amount of active ingredient was subsequently detected using HPLC-MS following exhaustive extraction of the skin with toluene. The mean value of 5 replications was 0.073 mg/100 g of evening primrose oil.

[0055] The high negative shear thinning exponent found for the spinning solution after having been established by a long shearing time and a high shear rate thus correlates with a very slow release of the incorporated evening primrose oil.

Example 2

[0056] A furnish prepared as described in Example 1 had added to it in an otherwise unchanged procedure a dispersion of 135 g of evening primrose oil, 545 g of n-dodecane and 91.1 g of fumed silica (Aerosil® R 106). The mixture, whose shear thinning exponent n was =−0.56 (curve b) in FIG. 1), is thereafter further treated and shaped similarly to Example 1. The staple fibers obtained were used to produce a web of the same composition and the same basis weight as in

Example 1

[0057] A mean value of 0.754 mg/100 g of evening primrose oil was determined on measuring the transfer of active ingredient.

[0058] Changing the active ingredient matrix composition leads to a lower negative shear thinning exponent being determined and a faster rate of active ingredient release being attained.

Example 3

[0059] A furnish prepared as described in Example 1 had added to it a concurrently fabricated dispersion of 2.242 kg of an 80% aqueous NMMO solution and 364.5 g of sheet-silicate (Cloisite® 30 B) after UltraTurrax dispersion for nearly 10 minutes, and further processed similarly to Example 1. The shear thinning exponent of the solution was −0.67 (curve c) in FIG. 1).

[0060] A mean value of 0.522 mg/100 g of evening primrose oil was determined on measuring the transfer of active ingredient.

[0061] The distinctly shortened shearing time as compared with Example 1 leads to a reduction in the absolute value of the shear thinning exponent which can be determined and causes a significant increase in the released amount of active ingredient as compared with Example 1.

Example 4

[0062] The furnish prepared as described in Example 1 had added to it in am otherwise unchanged procedure a dispersion of 13 5 g of α-tocopherol, 545 g of palm kernel oil and 91.1 g of fumed silica. The mixture, whose shear thinning exponent was −0.13, is thereafter further treated and shaped similarly to Example 1. The staple fibers obtained were used to produce a web of the same composition and the same basis weight as in Example 1.

[0063] A mean value of 1.290 mg/100 g of α-tocopherol was determined on measuring the transfer of active ingredient.

[0064] Compared with the examples already described, a change in the composition of the active ingredient matrix with otherwise comparable parameters again causes a distinct increase in the release rate.

Example 5

[0065] The furnish prepared as described in Example 1 had added to it in an otherwise unchanged procedure a dispersion of 135 g of W/O emulsion (urea, cocoa butter, wool wax alcohol), 545 g of n-octadecane and 91.1 g of fumed silica (HDE® N 20). The shear chinning exponent was determined as −0.04 (curve a) in FIG. 1). The mixture is thereafter further treated and shaped similarly to Example 1. The staple fibers obtained were used to fabricate a yarn in 30% of functional fibers and 70% of cotton, which was further processed into a fine circular knit piece.

[0066] A mean value of 2.680 mg/100 g of urea was determined on measuring the transfer of active ingredient.

[0067] W/O emulsions exhibit a very sensitive effect on the shear thinning exponent of the active ingredient matrix composition with otherwise comparable treatment parameters, the lowest shear thinning exponents and comparatively high rates of release.