Process

Abstract

A method of providing a modifier on the surface of an active-containing core-shell aminoplast microcapsule, including the covalent attachment of the modifier to the capsule shell surface by means of a coupling compound capable of covalent bonding to both shell and modifier by means of epoxy groups on the coupling compound. The method is especially useful for enhancing the substantiveness to fabrics of fragrance microcapsules added to laundry products.

Claims

1. A method of providing a modifier on the surface of an active-containing core-shell aminoplast microcapsule, comprising the covalent attachment of the modifier to the capsule shell surface by means of a coupling compound capable of covalent bonding to both shell and modifier by means of epoxy groups on the coupling compound.

2. The method according to claim 1, in which the shell is of melamine-formaldehyde resin.

3. The method according to claim 1, in which the modifier is selected from a polysaccharide and an enzyme.

4. The method according to claim 3, in which the enzyme is a lipase.

5. The method according to claim 1, in which the coupling compound is poly(ethylene glycol) diglycidyl ether having an M.sub.n of from 300-10,000.

6. The method according to claim 1, in which the coupling compound is glycidyl methacrylate.

7. The method according to claim 6, in which the epoxy group of the glycidyl methacrylate is first reacted with the aminoplast of the shell, and free-radical addition polymerisation is then initiated with other glycidyl methacrylate molecules, to provide a plurality of epoxy groups.

8. The method according to claim 1, in which the coupling compound is first attached covalently to the shell, and subsequently is covalently attached to the modifier.

9. The method according to claim 1, in which the coupling compound is first attached covalently to the modifier, and subsequently is covalently attached to the shell.

10. The method according to claim 3 in which the modifier is selected from polysaccharide and enzyme and the coupling compound from poly(ethylene glycol) diglycidyl ether and glycidyl methacrylate.

11. The method according to claim 1 in which the modifier is selected from polysaccharide and enzyme and the coupling compound from poly(ethylene glycol) diglycidyl ether and glycidyl methacrylate.

12. A modified core-shell aminoplast microcapsule containing an active core and comprising on the shell surface a modifier, the modifier being covalently bonded to the shell by means of a coupling compound that is covalently bonded to both shell and modifier by means of epoxy groups on the coupling compound.

13. The microcapsule according to claim 12, in which the modifier is selected from polysaccharide and enzyme and the coupling compound from poly(ethylene glycol) diglycidyl ether and glycidyl methacrylate.

14. The microcapsule according to claim 12, in which the active core is fragrance.

15. A laundry product adapted to provide encapsulated fragrance on a washed article, comprising a laundry product base and fragrance-containing microcapsules according to claim 14.

16. The method according to claim 5, in which the coupling compound is poly(ethylene glycol) diglycidyl ether having an M.sub.n of from 500-6,000.

Description

EXAMPLE 1: POLYSACCHARIDE GRAFTING USING POLY(ETHYLENE GLYCOL) DIGLYCIDYL ETHER (PEGDE) IN AN AQUEOUS MEDIUM

[0019] Synthesis Procedure:

[0020] In a first stage, PEGDE is grafted on to capsules by contacting 2 g of washed melamine-formaldehyde capsules containing a perfume with 7 g PEGDE in a 100 ml flask under magnetic stirring during two hours at 25 C. A solution of a polysaccharide (3 g dextrane) in 100 ml aqueous buffer solution (20 mM glycne/NaOH) at pH 11 was added to the flask. The mixture was stirred at 70 C. for three hours to complete the reaction. To isolate the capsules, the mixture was cooled down, the capsules filtered and rinsed with copious amounts of water in order to remove the non-reacted traces of reagents.

[0021] For the purpose of characterisation, the perfume was removed from the capsules by rinsing with acetone, and the capsules lyophilised using standard procedures.

[0022] ATR-FTIR data confirmed presence of all components that were used in the reactions: 1100 1/cm [COC (grafted PEGDE)], 1010 1/cm [COC (dextrane)], 1000 1/cm [COC (xyloglucane)].

EXAMPLE 2: POLYSACCHARIDE GRAFTING USING POLY(GLYCIDYL) METHACRYLATE (GMA)

[0023] Synthesis procedure in two steps.

[0024] 1. Grafting of Poly(Glycidyl) Methacrylate

[0025] 2 g of purified capsules containing a perfume was suspended in 13 ml DMF (dimethyl formamide) in a 100 ml flask under magnetic stirring. 7 g of GMA was added to this suspension, which was subsequently de-oxygenated by gentle nitrogen bubbling during 15 minutes. The flask was hermetically sealed and heated at 70 C. for four hours in order to perform the addition of the amino groups to the epoxide functionality of GMA.

[0026] 60 mg of AIBN (azobisisobutyronitrile) in 1 ml degased DMF was added to initiate radical polymerisation, which was conducted for the next 90 minutes at 70 C. The suspension was cooled and filtered in order to retain the functionalised capsules. They were rinsed on the filter using copious amounts of water to remove residues of reagents and solvent. For the purpose of characterisation, the perfume was removed from the capsules by rinsing with acetone, and the capsules lyophilised using standard procedures.

[0027] 2. Grafting of Dextrane onto GMA-Functionalised Microcapsules

[0028] The capsules synthesised in the first step were suspended in 13 ml DMSO (dimethylsulfoxide) containing 3 g of dextrane and 0.3 g of 4-(N,N-dimethylamino)pyridine (DMAP), in a 100 ml flask under magnetic stirring. The suspension was stirred at 70 C. for five hours. Upon cooling down, the mixture was filtered and the capsules rinsed with copious amounts of water. For the purpose of characterisation, the perfume was removed from the capsules by rinsing with acetone, and the capsules lyophilised using standard procedures.

[0029] Characterisation

[0030] (GMA-Functionalisation). [0031] Macroscopic observations: capsules became very hydrophobic and agglomerated strongly in an aqueous milieu; spherical morphology of the capsules preserved. [0032] Gravimetry: the weight of the product was significantly larger than that of the starting capsules, even by 1000%, depending on the amount of GMA used. [0033] TGA: characteristic behaviour of poly-GMA-degradation with its typical peaks observed [0034] ATR-FTIR: 3000 cm.sup.1 (CH.sub.2 of GMA), 1750 cm.sup.1 (CO of GMA), 1150 cm.sup.1 (CO of GMA) [0035] RAMAN-IR: spectrum typical of poly-GMA; at 1250 1/cm band typical for the epoxy group observed [0036] Solid state NMR (.sup.13C), (ppm): 44 (C.sup.epoxy), 48 (C.sup.epoxy), 70 (CH.sub.2.sup.GMA), 177 (CO.sup.GMA). [0037] XPS: total coverage of the melamine shell by poly-GMA confirmed also by the full masking of the N-atoms on the surface (not observed), and by the increase of the C- and O-proportions and the detection of CO bonds on the surface, as is typical for bulk poly-GMA.

[0038] (Dextrane Grafting onto GMA-Functionalised Capsules). [0039] Macrospocpic observations: capsules hydrophilic, well dispersable in water. [0040] ATR-FTIR: 1010 cm.sup.1 (CO of dextrane) [0041] RAMAN IR: disappearance of the epoxy band at 1250 1/cm [0042] Solid state NMR (.sup.13C), (ppm): 55-80 (broad peak of the carbon atoms of dextrane); disappearance of the epoxy signals at 44 and 48. [0043] XPS: total coverage of the melamine shell by poly-GMA and dextrane confirmed also by the full masking of the N-atoms on the surface (not observed), and by the increase of the C- and O-proportions on the surface. In addition, the detection of supplementary CO and CC bonds on the surface indicates that dextrane was grafted. [0044] Grafting of marked dextrane (by an alkyne or by a fluorescent marker fluoresceine isothiocyanate) confirmed by the detection of the marker groups (the alkyne by RAMAN IR and the fluorescent marker by fluorescence microscopy).

EXAMPLE 3: DEPOSITION OF THE CAPSULES FUNCTIONALISED BY DEXTRANE

[0045] Synthesis Procedure

[0046] In order to evaluate the number of capsules retained by a substrate (cotton was used), the capsules were functionalised by covalently grafting fluoresceine isothiocyanate (FITC) directly on to one sample of capsules and by grafting a fluoresceine isothiocyanate-modified dextrane on to another sample of capsules by means of the procedures described in Example 2.

[0047] The deposition was performed by contacting separate substrates, each a square piece of cotton (11 cm), with a magnetically-stirred suspension of 2 g of the two capsule samples in 30 ml water at 30 C. for 90 minutes. The substrate was subsequently rinsed with water at 30 C. in the same amount of water during 15 minutes. The deposition was evaluated using optical fluorescence microscopy and the result is shown in FIG. 1. FIG. 1a shows the results of the capsules without dextrane and FIG. 1b the capsules with dextrane. It is clear that the number of deposited capsules is much larger in the case of the dextrane-modified material than that with the unmodified capsules.

EXAMPLE 4: GRAFTING OF METHACRYLATE-FUNCTIONALISED POLYSACCHARIDE

[0048] Synthesis procedure in two steps.

[0049] 1. Functionalisation of the Polysaccharide by Methacrylate

[0050] To a solution of 3 g of polysaccharide dextrane in 20 ml DMSO at 25 C. under magnetic stirring, 200 mg of solid DMAP was added and the solution stirred for 15 minutes. To this mixture, 2 g of GMA was added and the stirring continued at 70 C. during 8 hours. The product was precipitated from the mixture by slow addition of a cold 1:1 acetone/isopropanol solution (200 ml) under vigorous stirring. The solid was isolated by filtration. For purification, the solid was re-dissolved in 100 ml DMSO and precipitated with the cold mixture of acetone/isopropanol three times, at the end of which the final product was collected as solid and preserved under protection from light at 4 C.

[0051] 2. Grafting on to Capsules

[0052] 2 g of washed capsules containing a perfume was suspended in a solution of the material prepared above in DMF (100 ml) under magnetic stirring at 25 C. in a 200 ml flask. To this suspension, 7 g of GMA was added and the solution degassed by a gentle nitrogen bubbling during 15 minutes. The flask was sealed and the suspension stirred at 70 C. for four hours. Subsequently, 60 mg AIBN was added as solution in 1 ml DMF and the stirring at 70 C. continued another 90 minutes. The reaction mixture was cooled, the solid product isolated by filtration and purified by washing with copious amounts of DMSO. The capsules were lyophilised according to standard procedures for the characterisation.

[0053] Characterisation

[0054] G-1 (GMA-Functionalised Dextrane) [0055] ATR-FTIR: 1720 1/cm (COO.sup.ester of acrylate) [0056] NMR (.sup.1H), (ppm): methacrylate peaks at 5-7 (RCHCH.sub.2) [0057] NMR (.sup.13C), (ppm): methacrylate peaks 18 (CH.sub.3), 129 (C(sp.sup.2)), 136 (C.sup.quart), 167 (C.sup.ester).

[0058] G (capsules) [0059] ATR-FTIR: 1010 cm.sup.1 (COC of dextrane), 1150 cm.sup.1 (CO of GMA)), 1750 cm.sup.1 (CO du GMA), 3000 cm.sup.1 (CH2- of GMA). [0060] XPS: total coverage of the melamine shell by GMA and dextrane confirmed also by the full masking of the N-atoms on the surface (not observed), and by the increase of the C- and O-proportions on the surface. In addition, the detection of supplementary CO, CO, and CC bonds on the surface indicates that both, GMA and dextrane, were grafted.

EXAMPLE 5: GRAFTING OF AN ENZYME (LIPASE) ON TO A CAPSULE SURFACE

[0061] Synthesis Procedure

[0062] 2 g of capsules, modified by surface grafting of GMA (procedure from example 2, step 1), was suspended under magnetic stirring in 13 ml of a buffer solution (20 mM sodium phosphate, pH 7) containing 0.1 g of sodium dodecyl sulphate (SDS). To this suspension, 20 g of a lipase solution was added (Palatase from Sigma-Aldrich at c>20 000 unit/gram) and the mixture was stirred at 37 C. for 24 hours. The modified capsules were isolated by filtration and rinsed with a copious amount of water. The final product was re-suspended in demineralised water and stored in the dark at 4 C.

[0063] The main function of the lipase is the hydrolysis of the lipids into fatty acids and glycerine. This reaction is widely used to evaluate the lipase activity after the immobilisation of the protein. In order to evaluate the activity of the lipase immobilised on the microcapsules, the capsules were suspended (at c=0.025 mass % of solid) in a gelatine-stabilised aqueous solution of olive oil (50% oil) and left without stirring at 35 C. for 24 hours. The results are shown in FIG. 2. FIG. 2a shows that the initial olive oil emulsion (left, clear and yellow) became a white, cloudy, two-phase system (right). NMR analyses of the liquids (FIG. 2b) showed that the white, cloudy liquid was an aqueous glycerine solution.

[0064] Acid-base titration of the white solid (fatty acids) confirmed its acid content in the solid 28 mmol/l, whereas only 2 mmol/l of acids was present in the starting olive oil.

[0065] A control experiment was prepared, where non-modified capsules (containing lipase that was not covalently bonded) were treated with the lipase solution described above. When contacted with the olive oil, these capsules did not show any hydrolytic activity whatsoever, showing that the lipase either does not remain adsorbed on the surface of the microcapsules, or that it is inactive if it did remain adsorbed.

[0066] In a similar experiment, an olive oil-stained cotton tissue was contacted with a suspension of the lipase-functionalised capsules (7 mass %) in demineralised water at 37 C. for 24 hours. No other agents (surfactants, bases or similar) were added to this suspension. The tissue was then rinsed. As can be seen from FIG. 3, the olive oil stain (left) had disappeared.