Microcapsules on textiles

Figure 7.2 Microcapsules on textile (a) before and (b) after rubbing.

Boh B., Staresinic M., and Sumiga B., October 5-8, 2011. Synthesis and applications of scented microcapsules in textile products. XIX International Conference on Bioencapsulation, Amboisc, Fiance. 

In using this new approach, conventional corona treatment is combined with injection in a reactive medium of microcapsules in aerosol form. Chemical nanotreatment or coating occurs when the aerosol condenses on the substrate at low temperature, resulting in a durable effect (most likely due to the formation of covalent bonds). An improved antistatic behavior is also obtained on textile substrates. Application is possible on both natural and synthetic fibers, as well as on thermosensitive hydrophobic substrates such as polypropylene and polyethylene. 

As formerly mentioned, complex coacervation is one of the most employed methods in the preparation of microcapsules aimed at application on textiles. However, use of toxic reagents for a cross-linked coacervate shell (such as glutaraldehyde) is a big limitation in even greater exploitation of a complex coacervation approach. Research on more environmentally friendly coacervate shell should be continued and expanded. 

Different methods of embedding microcapsules into textiles have often been compared using the same microcapsule-based formulation. A group of researchers studied benefits and drawbacks of impregnation technique and screen printing on... 

The technology for encapsulating microcapsules for textile applications dates back to the early 1980s, and the work of Nelson (2001) of NASA. Microcapsules usually have walls of less than 2 pm in thickness and 20 to 40 pm in diameter, as shown in Fig. 9.12. The microcapsules can be reduced by depositing a thin polymer coating onto small solid particles or on dispersions of solids in liquids. 

Based on the high number of preserved, intact microcapsules in the case of the washed thermochromic textile, the colouristic parameters alone could not be used to evaluate the functionality of the thermochromic textile, while the SEM micrographs suggest the presence of a sufficient number of preserved microcapsules to retain the thermochromic property (Figure 2.23). 

The absorption band at 1737-1744 cm c d be ascribed to the carbonyl vibration of camphor or bomyl acetate from mimoenc rsulated Rosemary oil. From Fig. 6 it is possible to see that the intensity of ftiis band increases when textile material encapsulated with Rosemary oil is heated on 150 (spectrum c). We can conclude that temperature of ISO is too high for file treatment of EC microcapsules and some of the... 

Interesting preparation methods for microcapsules adapted for textile appHca-tions include phase separation (coacervation, in-situ polymerization, Hposomes) and spinning (rotating) disc processes. A detailed discussion on microencapsulation techniques can be found in Chapter 1. 

Outlast controls the production of PCM-based microcapsules for incorporation into textiles and other materials, and the company frequently licenses other companies to produce and seU the microcapsules. Commercial examples include the Lurapret PCMs produced by BASF [8]. These are water-based products that create an optimum temperature balance in textiles. The new treatment offers a high degree of temperature regulation, resulting in a very consistent level of thermal comfort. The material ensures that the wearer feels equally comfortable in conditions of either extreme heat or cold. They function by absorbing excess body heat on physical exertion and returning the stored heat to the body when the temperature falls. 

The best way to obtain most benefit from textiles treated with microcapsules is, of course, to wash them by hand. This minimizes the loss of actives during washing and maximizes their effect on the skin when the item is worn. 

Microcapsules with deodorization properties can be used on clothing, socks, curtains, and automotive textiles to eliminate smoke and other malodors, thereby creating pleasant surroundings. Textile coatings can also be infused with fragrances, which may intake unpleasant odors, while imparting pleasant ones, with potential applications for marketing. 

The large surface area of microcapsules allows for the formation of a uniform and continuous coating on the surface of the fabric as well as in between the fibers (Liu et al., 2013). The reasons for microcapsules playing an important role in the controlled release of active agents could be found in the uniformity and reproducibility in release (Singh et al., 2010). The following sections will focus on microcapsule formation and their embedding into textile stmctures. 

Particular attention should be given during the preparation of the textile substrate for more efficient embedding of microcapsules. The pretreatments of textiles include chemical modification driving the material to be in a more functionalized state for bonding with other entities. These modifications could be based on treatment in aqueous media to improve the accessibility of fibers toward chemical reaction (Salaiin et al., 2012) or even using plasma technology for creation of reactive sites (Chatteijee et al., 2014). 

Chatteijee, S., Salaiin, F., Campagne, C., 2014. Development of multilayer microcapsules by a phase coacervation method based on ionic interactions for textile applications. Pharmaceutics 6, 281—297. 

Li, L., Liu, S., Hua, T., Au, M.W., Wong, K.S., 2012. Characteristics of weaving parameters in microcapsule fabrics and their influence on loading capability. Textile Research Journal, http //dx.doi.org/10.1177/0040517512454184. Pubhshed online before print August 14, 2012. 

Interesting effects can be produced in textiles by using photochromic colorants. Because of stability problems in processing, these are often either incorporated into a polymer matrix inside textile fibres [76] or microcapsules containing the photochromic material are coated onto textile surfaces [77]. While products, such as T-shirts which change colour in sunlight, are available on the market, at present the development of this area is limited due to difficulties in obtaining cost-efficient, durable products [58]. 

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