method

Abstract

A method of covalently bonding a modifier to a polymer microcapsule wall, the wall comprising an entity capable of reacting with an acrylic acid moiety, the method comprising providing a linking compound on the wall, the modifier subsequently being linked to the linking compound, the linking compound having formula (I), wherein n=1-30; R1, R2 and R3 are independently selected from the following moieties: R1 and R3 are H and Me; and X is selected from O and NH; and R2 is selected from CH2, CH2CH(OH)CH2 and CH2.CH2. The thus modified microcapsules exhibit enhanced affinity for substrates such as textiles when used in laundry formulations.

Description

[0001] The present disclosure relates to microcapsules, and more particularly to microcapsules that can be stably dispersed in aqueous liquids. More particularly, the present invention relates to surface modification of capsules to make them more substantive to substrates.

[0002] Microcapsules, capsules with a mean diameter of about 50 nm to several mm, are known and have been used for a period of time as a means of protecting encapsulated active ingredients until they are needed. The scope of encapsulated materials is very wide, such as dyes, cells, drugs, enzymes, pigments, flavoring agents and spices. A specific application is to use microcapsules to deliver spices in laundry applications, with the purpose of protecting spices until the moment they are needed, at which time spices are released from the capsule. Extensive capsule wall materials are known, ranging from gelatin to acrylic resins, polyureas and aminoplasts. Aminoplasts such as melamine-formaldehyde resins have been particularly popular because they form excellent capsules and the material is relatively cheap.

[0003] It is expected that microcapsules can be deposited on substrates so that they will remain there. It is also expected that dispersibility can be provided for microcapsules in aqueous liquids so that they remain dispersed, or at least are easy to redisperse. These are not the natural properties of most microcapsules, and this means that a modifier needs to be provided to the capsule. In this case, the modifier is a material that has affinity for both capsule and substrate, or a material that gives capsule easy dispersibility, and an ideal material can perform these two functions. In the case of providing fragrance on clothes during washing, this means that the modifier must provide affinity (substantivity) for a specific substrate, whether the substrate is natural, such as wool or cotton, or or synthetic, such as acrylic, polyamide or polyester, or a blend of these materials. Typical modifiers are nonionic polysaccharides, such as mannan, dextran, glucomannan, xyloglucan, hydroxyalkyl cellulose, dextran, galactomannan and mixtures thereof.

[0004] The modifier allows the microcapsules to be continuously attached to the substrate. The problem with using a modifier is that the attachment to the capsule is an equilibrium where the modifier molecules enter and exit the capsule.

[0005] It has been proposed to more firmly anchor the modifiers. One approach is to add the modifier to the dispersion of the fragrance when the capsule wall is formed, so that the modifier entangles with the formed wall, thereby anchoring the modifier in place. This is successful in some but not all cases. In addition, some modifiers can interact with some fragrance components in a way that changes the fragrance properties and therefore changes the desired hedonic effect.

[0006] Another suggestion is to covalently bind the modifier to the capsule wall. This has the advantage that the capsule can be formed and then post-modified. This depends on the presence of complementary reactive groups on both the wall and the modifier, but this is not usually the case. One suggested way to overcome this is to use a linking compound, i.e. a compound with functionality for both the capsule wall and the modifier. Examples of this technology can be found in International Publication Nos. WO2006 / 1172902, WO2010 / 1424012 and WO2018 / 149775.

[0007] It has now been discovered that microcapsules can be effectively physically fixed to a substrate by a novel mechanism. Thus, there is provided a method of covalently bonding a modifier to a polymer microcapsule wall, the wall comprising an entity capable of reacting with an acrylic acid moiety, the method comprising providing a linking compound on the wall, the modifier subsequently being linked to the linking compound, the linking compound having the formula I

[0008]

[0009] in

[0010] n = 1-30; R1, R2 and R3 are independently selected from the following parts:

[0011] R1 and R3 are H and Me; and

[0012] X is selected from O and NH; and

[0013] R2 is selected from the group consisting of CH2, CH2CH(OH)CH2 and CH2.CH2.

[0014] In addition, the present disclosure also provides microcapsules prepared by the method as described above.

[0015] In specific embodiments, n is 1-23, 1-20, 1-15, 1-10, and 1-5.

[0016] In a specific embodiment, the linking compound is a compound having an acrylate moiety (CH2=CH.COO-) at one end and a methacrylate entity (CH2=C(CH3).COO-) at the other end, i.e., one of R1 and R3 is H and the other is CH3).

[0017] In another specific embodiment, R1 and R3 are both H, or both CH3, and X is O, and the other parts are as described above.

[0018] In another specific embodiment, the linker compound is a compound of Formula II or Formula III:

[0019]

[0020] The compound of formula II is 3-(acryloyloxy)-2-hydroxypropyl methacrylate.

[0021] The polymer constituting the capsule wall may be any polymer containing entities capable of reacting with acrylic acid moieties, i.e. moieties containing a prop-2-enoyl group CH2=CH-CO-. Entities reactive with acrylic acid moieties are nucleophilic groups such as primary and secondary amines, hydroxyl groups, thio and phosphine (H-PR2) hypophosphite H2P(O)OH and phosphonates of the PO(OH)2 or H-PO(OR)2 type.

[0022] Specific examples of polymers incorporating amine groups are aminoplasts, such as urea- and melamine-formaldehyde resins and polyureas.

[0023] The modifier may be any suitable modifier capable of reacting with the linking compound to form a covalent bond and thereby permanently attached to the capsule surface. Typical examples of modifiers include polysaccharides such as mannan, dextran, glucomannan, xyloglucan, hydroxyalkylcellulose, dextran, galactomannan and mixtures thereof.

[0024] The method of the present invention is carried out by adding the linking compound to the capsule slurry, followed by the addition of the modifying agent, linking agent and initiator.

[0025] The degree of grafting of the modifier, ie the proportion of the added modifier that is attached to the capsules, can be determined by any suitable method, for example by gel permeation chromatography or viscosity measurement. Typical methods for sample preparation for GPC for grafting degree determination are described in the Examples.

[0026] Depending on the nature of the modification, the capsules thus modified are easier to redisperse (if this proves necessary) and have an enhanced affinity for the desired substrate.

[0027] The capsules thus modified have a greater affinity for the substrate, as a greater proportion of the capsules will adhere to the substrate, thereby providing a much enhanced olfactory experience.

[0028] The microcapsules described above can be incorporated into any treatment formulation applied to a substrate. It can be, for example, a laundry formulation, such as a laundry detergent (powder or liquid) or a fabric conditioner or softener. Therefore, the present disclosure also provides such a treatment formulation. The present invention also provides a method for enhancing the affinity of a microcapsule applied to a substrate as a component of a treatment formulation to a substrate, the microcapsules being prepared as described above.

[0029] The present disclosure is further described with reference to the following examples, which describe specific embodiments and are not intended to be limiting in any way.All proportions are by weight.

[0030] Example 1

[0031] Preparation of urea-melamine-formaldehyde capsules A containing fragrances grafted with hydroxypropyl cellulose

[0032] Materials and amounts are for 100 g slurry.

[0033]

[0034] 1. Alternating copolymer of ethylene and maleic anhydride

[0035] 2. Polymethylol-melamine precondensate

[0036] 3. Hydroxypropyl cellulose M CS dispersion

[0037] Prior to capsule preparation, 2.85% hydrolyzed ZeMac was prepared TM Solution of E400 in water. Similarly, a hydroxypropyl cellulose dispersion was prepared in advance the day before by dispersing the hydroxypropyl cellulose in a stirred glycerol / water solution at room temperature.

[0038] The reactor temperature was set to 35°C and then charged with: (10 g), Zemac TM E400 and urea. Adjust pH to 4.6±0.2 with NaOH solution while stirring, adjust stirring rate to obtain desired capsule size (15-20 μm). Add fragrance and continue stirring at 35°C.

[0039] Add some Luracoll TM SD (1.4 g) was added and the temperature was raised to 88°C. This temperature was maintained for 30 minutes, at which time the rest of the Luracoll was added. TM SD (0.6 g) was added and the temperature was maintained.

[0040] 3-(Acryloyloxy)-2-hydroxypropyl-methacrylate and HPC were added while maintaining stirring and temperature. Potassium peroxodisulfate was then added and the temperature was maintained. The rest of the water and ethylene urea were added before cooling the reaction mixture.

[0041] Capsule characterization: solid content 32%, expected 33%; d 50 =18μm; 5 / 21s -1 Viscosity at (25°C) = 3000 / 1500 mPa.s; grafted HPC ≈ 40%.

[0042] The degree of grafting was determined by the following method:

[0043] One volume of capsule slurry (typically 10 mL) was diluted in two volumes of ethanol and the mixture was placed in an ultrasonic bath at 25°C for 30 minutes. The liquid was evaporated, the solid residue was suspended in pentane and sonicated again for 20 minutes. The solid was filtered out and rinsed twice more with pentane. The off-white solid was collected from the filter and dried in air. The calculated amount of the powder (40-50 mg) was suspended in 5.0 ml of DMF, which was prepared as an eluent for gel permeation chromatography (0.1 mol / l of LiBr was dissolved in DMF, and the solution was first filtered with a 0.45 μm pore size filter and then filtered with a 0.2 μm pore size filter). The suspension was stirred at 60°C for 16 hours, filtered with a 0.45 μm pore size syringe filter and injected into a gel permeation chromatography system. It was separated by three columns (Waters Styragel 4, 5 and 6, all 7.8×300 mm), covering a total molecular weight range of 6x10 6 g / mol. The detection system consisted of a Heleos II Dawn8+ multi-angle laser light scattering (MALLS) and a differential refractive index (dRI, Optilab T-Rex) detector (both from Wyatt Technologies), allowing the detection and quantification of residual (ungrafted) surface modifiers. Separation conditions: 0.5 mL / min flow rate, 50 °C, DMF / 0.1 M LiBr as eluent.

[0044] This allowed the recovery of free, ungrafted polymer to be determined and the difference with the total polymer used for grafting yielded the amount of grafted polymer.

[0045] Example 2

[0046] Preparation of urea-melamine-formaldehyde capsules containing fragrance using non-HPC polysaccharides B

[0047] Example 1 was repeated in exactly the same manner, except that 0.5 g of the polysaccharide modified with ammonium functional groups was used instead of HPC.

[0048] Capsule slurry characterization: solid content 32.4%, expected 33.5%; d 50 =7μm; 5 / 21s -1 Viscosity at (25°C) = 4000 / 1900 mPa.s;

[0049] Example 3

[0050] Preparation of urea-melamine-formaldehyde capsules containing fragrance using hydroxypropyl cellulose grafting

[0051] In a closed reactor equipped with a mechanical stirrer, 26 g of hydrolyzed ZeMac TME400 solution (2.9%) and 16g of water were added and stirred at 200RPM for 3 minutes. Stirring was then stopped and the fragrance (33g) was added to the reactor, followed by 0.2g of Dynasylan TM AMEO (3-aminopropyltriethoxysilane). Stirring (700 rpm) and heating were then started, and upon reaching 35° C., the pH was adjusted to 6.0 using aqueous NaOH solution. Stirring was maintained at 35° C. for 1 hour, at which point the pH was adjusted to 4.6 using aqueous formic acid solution. Luracoll SD (1.2 g) and urea (0.8 g) were added to the stirred solution, and heating was increased to reach 90° C. 30 minutes after reaching 90° C., 0.7 g Luracoll was added and heating continued for another 120 minutes.

[0052] 0.1 g of 3-(acryloyloxy)-2-hydroxypropyl methacrylate and 0.55 g of HPC were added to the reactor, followed by potassium persulfate (KPS, 1 g of a 4% aqueous solution) in two portions over the next hour. After another hour, 4 g of an aqueous solution of ethylene urea (30%) was added, followed by about 16 g of water. The slurry was cooled to 25° C. over 1-2 hours.

[0053] Capsule slurry characterization: d 50 =17μm; 5 / 21s -1 Viscosity at (25°C) = 2800 / 1800 mPa.s; % grafted HPC ≈ 60%.

[0054] Example 4

[0055] Preparation of polyurea capsules containing fragrance using hydroxypropyl cellulose grafting D

[0056] Material:

[0057]

[0058] 1. Emulsion stabilizer

[0059] 2. Polyethyleneimine

[0060] 3. Monomeric alicyclic diisocyanates

[0061] 4. Hydrophilic aliphatic polyisocyanate

[0062] 5. Potassium persulfate

[0063] Into a reactor equipped with a mechanical stirrer are introduced: water, Floset DP CAPS371L and Bayhydur XP2547 at 25°C with gentle stirring, at which point the stirring rate is increased to 1300 rpm. The isocyanate Desmodur and the fragrance are added simultaneously to the stirred mixture and stirring is continued for 30 minutes.

[0064] Lupasol TM A solution of G100 in water was added to the stirred mixture and heating was started, gradually increasing the temperature from 25°C to 85°C over 3 hours and maintained at this temperature for another 2 hours.

[0065] 3-(Acryloyloxy)-2-hydroxypropyl-methacrylate was then added, followed by HPC (hydroxypropylcellulose, KPS and AIBN solutions at 30 minute intervals. The temperature and stirring were maintained for a further hour while the ammonia was added. After a brief stirring, the mixture was cooled to 25°C.

[0066] Characterization: Solids 43.2%, expected 42.1%, d 50 : 14.8μm; HPC grafting: 60-70%

[0067] Example 5

[0068] Preparation of resorcinol-melamine-formaldehyde capsules E containing fragrances grafted with hydroxypropyl cellulose

[0069] Material:

[0070]

[0071] In a reactor equipped with a mechanical stirrer, water, resorcinol, Floset TM DP / CAPS 371L and Luracoll TM SD and start stirring at 400 rpm. Once the mixture is homogenized, add the fragrance and increase the stirring rate to 950 rpm. Use formic acid to adjust the pH to 3.5-4.0. Gradually increase the temperature to 75°C and maintain for 1 hour. Adjust the pH again with formic acid and maintain stirring at 75°C for another 1 hour.

[0072] 3-(Acryloyloxy)-2-hydroxypropyl methacrylate and HPC were added to the reactor at 75° C., followed by the addition of KPS over the next hour. Stirring was continued for an additional hour at 75° C. The ethylene urea solution was added and stirring was continued for an additional hour at 75° C., at which point heating was stopped and the mixture was cooled to 25° C.

[0073] Capsule characterization: d 50=10.7 μm; solids content 31.7%, expected 33.3%; % HCP grafted: ~40%.

[0074] Example 6

[0075] Preparation of urea-melamine-formaldehyde capsules F containing fragrance without surface modification

[0076] For comparative purposes, capsule F was synthesized according to the method described in Example 1, but the grafting step was omitted, i.e., no HPC, no 3-(acryloyloxy)-2-hydroxypropyl-methacrylate, and no KPS were added to the reaction system. This is an example of a capsule without surface modification.

[0077] Capsule characterization: solid content 30%, expected 31%; d 50 =17μm; 5 / 21s -1 Viscosity at (25°C) = 1200 / 700 mPa.s.

[0078] Example 7

[0079] Preparation of urea-melamine-formaldehyde capsules containing fragrances modified with xyloglucan by co-entrapment

[0080] For comparative purposes, capsule G was synthesized according to the method of Example 1, but HPC, 3-(acryloyloxy)-2-hydroxypropyl-methacrylate and KPS were omitted. The difference from capsule A was the addition of 0.3 g xyloglucan at 88°C and the addition of Luracoll SD. This is an example of a capsule in which the surface modification is performed by co-embedding the modifying agent in the outer layer of the capsule surface.

[0081] Capsule characterization: solid content 32%, expected 33%; d 50 =17.5μm; 5 / 21s -1 Viscosity at (25°C) = 2800 / 1100 mPa.s.

[0082] Example 8

[0083] Preparation of urea-melamine-formaldehyde capsules containing fragrances modified with hydroxypropyl cellulose by co-encapsulation

[0084] For comparative purposes, capsule H was prepared according to the method of Example 1, but 3-(acryloyloxy)-2-hydroxypropyl-methacrylate and KPS were omitted. HPC (same amount as in Example 1) was added together with Luracoll at 88° C. This is an example of a capsule in which the surface modification is carried out by co-embedding the modifying agent in the outer layer of the capsule surface.

[0085] Capsule characterization: solid content 19%, expected 33%; d 50 =17μm; 5 / 21s -1 Viscosity at (25°C) = 3000 / 1500 mPa.s; grafted HPC ≈ 20%.

[0086] Low solids content measurements indicate that the capsules do not resist drying, that is, the encapsulated flavor leaks out of the capsules when they are dried, either because they rupture mechanically or because of insufficient impermeability of the shell to prevent evaporation of the flavor. Either way, this represents an example of poor flavor encapsulation, probably as a result of the modifier molecules interfering with the encapsulation process.

[0087] Example 9

[0088] Proof of the necessity of the required components for grafting of modifiers

[0089] Example 1 was repeated, omitting one or more of the molecules used in the grafting stage (indicated by "-" for the absence of the molecule and "+" for the presence of the molecule). Thus, number 1 in the table below represents a synthesis in which only HPC was added and the linker and free radical initiator were omitted. Entries 5-7 in the table describe the variation of the free radical initiator and its effect on the grafting. The grafting percentage was determined by the method described in Example 1.

[0090]

[0091] It can be observed that:

[0092] - In Nos. 1-3, almost no HPC was grafted (recovery was almost complete), indicating that the absence of one of the modifier (HPC), linker or initiator resulted in almost no grafting.

[0093] - In No. 4 (same as Example 1), there is 50% grafting, a significant result.

[0094] - In No. 5, the application of AIBN initiator (oil soluble) delivered slightly worse results than No. 4, but still acceptable.

[0095] - In No. 6, the combination of both initiator strips showed no improvement over KPS used alone.

[0096] - In No. 7, the same results as in No. 4 were obtained using 2,2'-azobis-(2-methylpropionamidine)-dihydrochloride initiator.

[0097] Example 10

[0098] Demonstration of the Olfactory Benefits of HPC Grafted on Polyester Substrates (T-shirts)

[0099] Polyester is known to be a difficult substrate for fragrance deposition, especially for the deposition of encapsulated fragrances, which may be attributed to the smooth and hard surface of polyester fibers, which provides very small contact area for fragrance capsules, requiring high adhesion energy between the two objects to achieve high olfactory performance.

[0100] Liquid detergent samples containing capsules A, C, F, G and H as prepared in Examples 1, 3, 6, 7 and 8, respectively, were prepared by dispersing a slurry of these capsules in the same amount (50 g) of liquid detergent base. The level of perfume concentration was the same in all samples. Each wash cycle was performed in a standard European washing machine (front load) with 5 cotton towels and three polyester T-shirts, with additional cotton pieces to complete the machine load to 5 kg.

[0101] When dry, the post-friction aroma enhancement performance was evaluated by recording the level of aroma intensity perceived after gentle rubbing of the substrate to crush the capsules and release the fragrance. The fragrance was evaluated by a panel of 7 expert testers. Capsule G was used as the standard (Capsule G in which the modifier was incorporated by an embedding method recognized in the art). The olfactory evaluation was based on the following scale:

[0102] 1- No difference or worse than standard capsules

[0103] 2- Slightly stronger than standard capsules

[0104] 3 – Significantly stronger than standard capsules

[0105] 4- Much stronger than standard capsules.

[0106] The values ​​are averaged and the result is displayed in Figure 1 As can be seen, the performance of samples where the modifier was covalently grafted (A and C) is significantly higher than that of the other samples. Capsule I with its low performance suggests that the co-encapsulation approach to surface modification is not the way to introduce this particular modifier. Although capsule G can be prepared by co-encapsulation, its performance is still lower than that of A and C, but higher than that of the unmodified capsule F.

[0107] Thus, this example not only demonstrates the benefit of surface modification of capsules for higher olfactory performance (F vs. A, C, and G), but also highlights the advantages of covalent grafting over co-encapsulation strategies, especially when the molecule of interest is not amenable to encapsulation approaches.

[0108]

Claims

1. A method for covalently bonding a modifier to a polymer microcapsule wall, the wall comprising an entity capable of reacting with an acrylic acid moiety, the method comprising providing a linking compound on the wall to which the modifier is subsequently linked, the linking compound having the formula I in n = 1-30; R1, R2 and R3 are independently selected from the following moieties: R1 and R3 are independently selected from H and Me; and X is selected from O and NH; and R2 is selected from the group consisting of CH2, CH2CH(OH)CH2 and CH2.CH2.

2. The method of claim 1, wherein n is selected from 1-23.

3. The method of claim 1, wherein n is selected from 1-20.

4. The method of claim 1, wherein n is selected from 1-15.

5. The method of claim 1, wherein n is selected from 1-10.

6. The method of claim 1, wherein n is selected from 1-5.

7. The method of claim 1, wherein the linking compound is a compound having an acrylate moiety (CH2=CH.COO-) on one end and a methacrylate entity (CH2=C(CH3).COO-) on the other end.

8. The method of claim 1, wherein R1 and R3 are both H or both CH3, and X is O.

9. The method of claim 1, wherein the linking compound is a compound selected from the group consisting of compounds of Formula II and Formula III:

10. The method of claim 9, wherein the linking compound is 3-(acryloyloxy)-2-hydroxypropyl methacrylate.

11. The method of claim 1, wherein the polymer microcapsule wall comprises amine groups.

12. The method of claim 11, wherein the polymer material of the microcapsule wall is selected from the group consisting of aminoplasts and polyureas.

13. The method of claim 12, wherein the aminoplast is selected from the group consisting of urea- and melamine-formaldehyde resins.

14. The method of claim 1, wherein the modifying agent is selected from at least one polysaccharide.

15. The method of claim 14, wherein the polysaccharide is selected from the group consisting of mannan, dextran, glucomannan, xyloglucan, hydroxyalkylcellulose, galactomannan, and mixtures thereof.

16. The method of claim 1, wherein the microcapsules comprise a fragrance.

17. Microcapsules prepared by the method of claim 1.

18. A treatment formulation comprising the microcapsules of claim 17.

19. A treatment formulation according to claim 18, wherein the formulation is a laundry formulation.

20. A method of enhancing the affinity of microcapsules for a substrate to which the microcapsules are applied as part of a treatment formulation, the microcapsules being prepared according to the method of claim 1.

21. The method of claim 20, wherein the treatment formulation is a laundry product and the microcapsules comprise a perfume.

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