WO2005005712A2

WO2005005712A2 - Compound and method of applying additives to fabrics, microcapsule, and method for preparing said compound

Info

Publication number: WO2005005712A2
Application number: PCT/IB2004/051156
Authority: WO
Inventors: Amar A. Mavinkurve; Sima Asvadi; Eduard J. Hultermans; Paul A. J. Ackermans; Rifat A. M. Hikmet; Wilma Van Es-Spiekman; Johannes W. Hofstraat
Original assignee: Koninklijke Philips Electronics N.V.
Priority date: 2003-07-14
Filing date: 2004-07-07
Publication date: 2005-01-20
Also published as: WO2005005712A3

Abstract

The invention relates to a compound for applying additives to fabrics, comprising a carrier liquid,a binder and microcapsules dispersed in said carrier, each microcapsule comprising: a core provided with at least one additive and a coating encapsulating said core at least partially. The invention also relates to a fabric provided with such microcapsules. Additionally, the invention relates to a method of preparing such microcapsules. Furthermore, the invention relates to a method of applying additives to fabrics by using such a compound.

Description

Compound and method of applying additives to fabrics, microcapsule, and method for preparing said compound

The invention relates to a compound for applying additives to fabrics, comprising a carrier liquid, and microcapsules dispersed in said carrier liquid, each microcapsule comprising a core and a coating encapsulating said core at least partially, wherein each microcapsule is provided with at least one additive. The invention also relates to a fabric provided with such microcapsules. Additionally, the invention relates to a method of preparing such microcapsules. Furthermore, the invention relates to a method of applying additives to fabrics by using of such a compound.

Compounds according to the preamble are known from the prior art. The known microcapsules, also known as core-shell particles, can be provided with an additive, such as a fragrance. Fragrances or perfumes commonly form an important aspect of fabric laundry processes. The known compound provided with the perfume can be applied to the fabric, e.g. during ironing, washing or drying. As perfume is commonly relatively highly volatile, it is often desired to slow down the evaporation rate and to prolong the effect of the perfume, i.e. to give a pleasant sensation for a long time when inhaled by persons. A way to control and to slow down the evaporation process is by forcing the fragrance to diffuse through a solid or liquid medium. In order to do this, it is necessary to incorporate the fragrance into a solid medium. Core-shell particles are normally ideally suited for this purpose. The American patent US 6,024,943 discloses solid microcapsules provided with fragrance, wherein each microcapsule is made of a solid organic polymer core, with a solid further polymer encapsulating said core. By using such a core-shell structure for the microcapsule, a retention or controlled release of perfume can be achieved. The known microcapsule has several drawbacks. A major drawback of the known microcapsule is that these microcapsules commonly interact relatively badly with fabrics, resulting in a relatively weak binding of the microcapsules to the fabric. This means that the microcapsule will detach itself from the fabric relatively easily, as a result of which solely a limited quantity of the additives originally applied will be released near to or in the fabric. It is an object of the invention to provide an improved compound for applying additives to fabrics, with which an improved binding of microcapsules to a fabric can be established. The object of the invention can be achieved by a compound according to the preamble, characterized in that said compound also comprises at least one binder agent dispersed in said carrier liquid for binding the microcapsule to the fabric. By using one or more binder agents dispersed in the carrier liquid (initially as separate particles), an improved interaction of the microcapsules with the fabric can be established after application of the microcapsules to the fabric. After application of the compound to the fabric the particles of the binder agent will usually form a matrix in which the microcapsules as fillers will be encapsulated relatively firmly. Therefore, (at least) all microcapsules applied to the fabric will remain at the fabric and will release the additive adjacent or in the fabric. This implies that the binding of the additives to a fabric and the compound according to the invention will be increased compared with the binding of the additives incorporated in the microcapsules known of the prior art. Thus, the microcapsules of the compound according to the invention will commonly last longer on the fabric, resulting in an improved binding of the compound. A general advantage of the core-shell microcapsules is that both the core and the shell can be separately optimized for their purpose. In the microcapsules of the compound according to the invention, this optimalization could be, for example, to improve the carrying capacity of additives of the core and to enlarge the interaction capacity of the coating or shell with respect to the binding agent. It is noted that the binder agent also controls the release of additive, whereby a controlled release of additives can be achieved as well as an improved binding of the microcapsules to the fabric. The thickness of the coating can be tuned to control the rate of release of the additive, since the diffusion time commonly scales as the square of thickness of the coating. In a preferred embodiment, said binder agent comprises at least one fusible polymer. A polymer is commonly advantageous as it can commonly be prepared in a relatively cheap and simple way. Suitable polymers for the binding of the microcapsules to the fabric are, for example: polyurethanes, polybutadienes, and acrylate copolymers (for example of butyl acrylate and acrylic acid, preferably in a ratio of 80: 20). Preferably, the additive is formed by a fragrance. However, the compound may also be used to apply other kind of functional additives to fabrics such as, for example, anti-bacterial and anti-fungal substances and coloring agents. In a preferred embodiment, the core is provided with one of these additives. In another preferred embodiment, however, the core is preferably provided with multiple additives. Examples of these additives were mentioned above. In a preferred embodiment, the coating is provided with at least one additive.

In this way an additional substance is added to the microcapsule. This additional substance, for example (another) perfume, or a coloring agent, will be released (substantially) faster than the additives held by the core. In another preferred embodiment, the carrier liquid is substantially formed by an aqueous medium because of environmental and health considerations. Preferably, health aspects should also be taken into account in the choice of the size of the microcapsules. The microcapsules may be prepared, for example, such that they fuse when the carrier liquid has evaporated. This approach would combine two advantages: firstly the microcapsules are optimally suited to adhere to the fabric (via the binder agent), and secondly any health risk related to inhalation of microcapsules is eliminated or at least strongly reduced. The core is preferably substantially hydrophobic and may be formed, for example, by polystyrene or a copolymer of styrene and butadiene. In another preferred embodiment, the coating is substantially hydrophilic. The coating or shell may be made up, for example, of polymethylmethacrylate (polyMMA) or of a hydrophilic water-swellable polymer, like polyacrylic acid (PAA) and polyvinyl alcohol (PVA). The water-swellable polymer will swell when subjected to moisture during wear, e.g. due to sweating, resulting in an increased rate of diffusion of the additive molecules from the microcapsules. However, it is also imaginable to apply a swellable polymer in the core because the coating can be fully optimized with respect to the interaction with the binder agent in that case. In yet another preferred embodiment, the microcapsules are substantially spherical. Substantially spherical microcapsules are commonly easy to prepare, for example during an emulsion polymerization. However, it is also conceivable to generate microcapsules with other shapes. In another preferred embodiment, the compound is (substantially) removable by washing. If a fusible elastomer - which is removable by washing - is applied as a binder agent, the compound as a whole, including the additive and microcapsules, will usually be washed out. An example of a fusible elastomer which is removable by washing consists substantially of a copolymer of butyl acrylate and acrylic acid, preferably in the ratio of 80:20. However, it is also conceivable to apply a more durable active ingredient which is not, or at least hardly, removable by washing. The invention also relates to a fabric provided with such a compound. Preferably, the binder agent forms a matrix encapsulating the microcapsules at least partially. Additionally, the invention relates to a method of preparing such microcapsules, comprising the steps of: 1) creating polymeric cores in a liquid medium, 2) creating a polymeric coating around at least a proportion of said cores in said liquid medium, 3) adding at least one additive to said liquid medium, 4) permitting the additive to infuse into at least a proportion of said cores, and 5) adding a binder agent dispersion to the formed microcapsules dispersion. The creation of the core-shell particles according to this method commonly occurs via emulsion polymerization. The additives may be mixed with the core- shell emulsion. The (organic) molecules of the additive will infuse into the formed microcapsules. In this situation, one will have a relatively high degree of freedom as regards to the choice of the additive. The liquid medium is then preferably formed by an aqueous medium. It may be necessary to add an additional amount of additive to the aqueous medium to restrict the (contra)diffusion of additive molecules from the formed microcapsule structures. The additional amount may equalize or exceed the saturation limit of the additive in the aqueous medium, but it is noted that the saturation limit of an organic additive in water is relatively low. The binder agent emulsion can be mixed with the formed core-shell emulsion if there is a sufficient mixing compatibility with respect to ionic properties of the two emulsions. In another preferred embodiment, steps 3) and 4) are carried out before step 2) is carried out. In this case the functional additives, e.g. the fragrance molecules, may be incorporated into the core during the polymerization. If the nature of the additive is organic, then the additive may be combined with the monomer during the polymerization, thereby forming the cores provided with the additive. This pre-mix process is only possible if the additive does not significantly interfere with the polymerization process. Furthermore, the invention relates to a method of applying additives to fabrics by use of such a compound, comprising the steps of: applying the compound to the fabric, permitting the carrier liquid to evaporate at least partially, and permitting the binder agent to attach itself to the fabric. The first two steps can be carried out synchronously. During the last step, the binder agent of the compound will adhere to the fibers of the fabric in a firm, stable and durable way, thereby encapsulating the microcapsules relatively solidly. To improve the binding of the microcapsules to the fabric via the binding agent, the local temperature of the compound is preferably increased after the application of the compound to the fabric. This increased temperature may be achieved, for example, by ironing of the fabric. By increasing the temperature of the fabric and of the microcapsules, the particles of the binding agent will commonly become more sticky and will often fuse together, resulting in an improved matrix as a binding intermediary between the microcapsules on the one hand and the fabric on the other. This matrix commonly encapsulates the microcapsules including the additives at least partially, as a result of which the additive molecules will have to diffuse through to matrix in order to leave both the microcapsules and the mutually fused binding agent particles. Consequently, a controlled or programmed release of the additive in the fabric will be achieved. The invention may be further illustrated by way of the following non- limitative example. Example An aqueous emulsion is prepared by mixing equal quantities of a 40% aqueous emulsion of Permutex RU-4049® and a 10% latex of Estapor® [175 - 225 nrn core-shell particles based on poly(styrene-co-butadiene)], and dilution with water until a solids content of 5% by weight is obtained. This emulsion is applied to a piece of fabric by spraying or by soaking the piece of fabric in the emulsion until a total pick-up of 100% is obtained with respect to the conditioned fabric weight. After drying of the treated fabric until the additional weight (with respect to the conditioned fabric weight) is about 15%, the fabric is ironed dry. Although most of the core-shell particles are to be found below the surface of the coating, it can be observed with a SEM (Scanning Electron Micrography) device that some of the particles which lie at the surface portion of the fabric are strongly and firmly bound to the fusible polymer matrix owing to the film-forming ability of the latter. It must be clear that the invention is by no means limited to the embodiments described afore. Within the framework of the claims as enclosed, a variety of other embodiments are possible which will be obvious for a person skilled in the art.

Claims

CLAIMS:

1. Compound for applying additives to fabrics, comprising: a carrier liquid, and microcapsules dispersed in said carrier liquid, each microcapsule comprising: - a core, and - a coating encapsulating said core at least partially, wherein each microcapsule is provided with at least one additive, characterized in that said compound also comprises at least one binder agent dispersed in said carrier liquid for binding the microcapsule to the fabric.

2. Compound according to claim 1, characterized in that said binder agent is provided with at least one fusible polymer.

3. Compound according to claim 1 or 2, characterized in that the additive is formed by a fragrance.

4. Compound according to any one of the foregoing claims, characterized in that the core is provided with at least one additive.

5. Compound according to any one of the foregoing claims, characterized in that the coating is provided with at least one additive.

6. Compound according to any one of the foregoing claims, characterized in that the carrier liquid is substantially formed by an aqueous medium.

7. Compound according to any one of the foregoing claims, characterized in that the core is substantially hydrophobic.

8. Compound according to any one of the foregoing claims, characterized in that the coating is substantially hydrophilic.

9. Compound according to any one of the foregoing claims, characterized in that the microcapsules are substantially spherical.

10. Compound according to any one of the foregoing claims, characterized in that the binder agent is provided with at least one additive.

11. Compound according to any one of the foregoing claims, characterized in that the compound is substantially washable.

12. Fabric provided with a compound according to one of the claims 1 to 11.

13. Fabric according to claim 12, characterized in that the binder agent forms a matrix encapsulating the microcapsules at least partially.

14. Method of preparing a compound according to any one of the claims 1 to 11, comprising the steps of: 1. creating polymeric cores in a liquid medium, 2. creating a polymeric coating around at least a proportion of said cores in said liquid medium, 3. adding at least one additive to said liquid medium, 4. permitting the additive to infuse into at least a proportion of said cores, and 5. adding a binder agent dispersion to the formed microcapsules dispersion.

15. Method according to claim 14, characterized in that steps 3) and 4) are carried out before step 2) is carried out.

16. Method of applying additives to fabrics by use of a compound according to any one of the claims 1 to 11, comprising the steps of: - applying the compound to the fabric, permitting the carrier liquid to evaporate at least partially, and permitting the binder agent to attach itself to the fabric.

17. Method according to claim 16, characterized in that the local temperature of the compound is increased after the application of the compound to the fabric.