Microencapsulated Colorants for Technical Textile Application

Keywords

Microencapsulated dyes and pigments, liposomes, in-situ polymerization, interfacial polymerization, coacervation, molecular complexation, textiles, fragrance, phase-change materials.

Introduction

Microencapsulation can be used to deliver everything from improved nutrition to extended shelf life. In fact, it’s one of the greatest opportunities to expand a brand’s potential. A wide range of chemical-based microencapsulation technologies have been applied widely within the textile industry, concentrating on specific applications within the dyeing and printing sectors.

The textile roots of microencapsulation technology were introduced as were the wide range of applications in food and other business sectors. In general, the number of commercial applications in the textile industry continues to grow particularly in the textile industries of Western Europe, Japan, and North America.

Microencapsulation is a process in which tiny particles or droplets are surrounded by a coating to give small capsules with many useful properties. The material inside the microcapsule is referred to as the core, internal phase, or fill, whereas the wall is sometimes called a shell, coating, or membrane.

Most microcapsules have diameters of a few micrometers. Manufacturing costs are based on coating material, solvent, equipment, and labor. Coating-material prices vary greatly, and as a rule, the cheapest acceptable material is used. Coatings that can be applied without solvent or water are preferred. Environmental and safety regulations greatly increase the cost of processes that use volatile organic solvents.

Characteristics

The following are the characteristics of a microcapsule:

Size and Size Distribution

Low size increases the mechanical strength as also ease of application.

Loading Fraction

This is the weight ratio of core to wall of the microcapsule, the higher is this ratio the better is the production efficiency but poorer would be the stability.

Release Properties

Rate of release from microcapsules depends largely on the structure of the polymer wall preparations. Wall characteristics play a big role in determining the release rate. As the crystallinity and cross-link density of the wall increases, the release rate reduces substantially.

Thermal stability

The microcapsule during its formation and application should be stable at higher temperatures.

Applications in Textiles

Industry has encouraged the use microencapsulation processes as a means of imparting finishes and properties to fabrics which were not possible or cost-effective using other technology. Textile manufacturers are demonstrating increasing interest in the application of durable fragrances to textiles as well as skin softeners; other potential applications include insect repellents, dyes, antimicrobials, phase change materials.

Microencapsulation in Medical Application

Microencapsulation has also found use in aromatherapy. A technology to microencapsulate functional oils like vitamins and Aloe Vera plant extract and use in textile finishing. It gives energetic balance to the human body and makes the fabric soft and comfortable. Technology of microencapsulating liposomes on the textile substrate yields controlled and targeted release of anti-cancer and anti-fungal drugs.

Microencapsulation of Antimicrobial Agents

Anti-microbial agents are incorporated with the textile material to prevent the transmission of pathogenic microorganisms from development of odor. Yeast cells containing biocide or insecticide have been applied to cotton, cotton wool and wool fabric. Mothproof agents have also been encapsulated in yeast and applied to wool fabric.

Microencapsulation of Fragrance

Our sense of smell is the strongest and does not rest even when we sleep. Using the sense of smell by building a fragrance into a textile or garment can stimulate a powerful and emotive sense. Fragrances can range from fine fragrances, florals, fruits, and malodor counteractants to aromatherapy.

Skincare Active Ingredients for Fabrics

Adding skin benefits to a textile is achievable by applying encapsulated moisturizers, essential oils, certain vitamins and even insect repellent. The use of encapsulated cosmetic oils is especially recommended to add skin benefits to hosiery, nightwear, and sportswear. Aleo Vera has been known for centuries as a medical plant whose properties contain a wide range of healing benefits and in cosmetic preparations. The use of Aloe Vera in cosmetics is especially recommended because of its positive effects on skin.

Insect Repellents

Menthoglycol is a natural insect repellent active ingredient, derived from lemon eucalyptus, which is a natural and renewable source. Fabrics treated three months previous with microencapsulated menthol glycol completely repelled foraging mosquitoes in nature, in exposure conducted over a four-hour period. The outcome of this test certainly suggests that micro encapsulation may greatly extend the effective lifespan of the mentholglycol insect repellent.

Microencapsulation: The Future

The ideal feature for most textile applications using microcapsules would be a system that is easy to apply, does not affect the existing textile properties and has a shelf-life on a garment that allows normal fabric-care processes to take place. Capsules can survive 25-30 wash cycles. Microencapsulation may deliver these long-term goals.

The desire for a healthier and more productive lifestyle will continue to generate a market for textiles that promotes “well-being”. Textiles that interact with the consumer, reducing stress, promoting comfort and relaxation, are possible through active delivery from microcapsules. In the last decade the textile industries have concentrated on developing performance fabrics with added value for sports and outdoor application, as well as novel medical textiles.

Conclusion

Microencapsulation applications in textiles are as wide as the imagination of textile designers and manufacturers. Early success for some companies in producing microencapsulated finishes for textiles have come about from collaboration and adaptation of technology from other industrial sectors.