Microencapsulation Techniques, methods and applications in Textiles

1. Finishing using
Microcapsules

2. Microcapsules - Definition
It is the process by which individual particles
or droplets of solid or liquid material (the
core) are surrounded or coated with a
continuous film of polymeric material (the
shell) to produce capsules in the micrometer
to millimetre range, known as microcapsules.

3. Microcapsules - Morphology
Depends mainly on the core material and the deposition process of
the shell.
Mononuclear (core-shell)
microcapsules contain the
shell around the core.
Polynuclear capsules have
many cores enclosed
within the shell.
Matrix encapsulation in which
the core material is distributed
homogeneously into the shell material.
In addition, microcapsules can also be mononuclear with multiple
shells, or they may form clusters of microcapsules.

4. Microcapsules – Coating
Coating materials for the Shell- properties requirements
•Stabilization of core material.
•Inert toward active ingredients.
•Controlled release under specific conditions.
•Film-forming, pliable, tasteless, stable.
•Non-hygroscopic, no high viscosity, economical.
•Soluble in an aqueous media or solvent, or melting
•The coating can be flexible, brittle, hard, thin etc.

5. Microcapsules – Coating
Coating materials:
•Gums: Gum arabic, sodium alginate, carageenan.
•Carbohydrates: Starch, dextran, sucrose
•Celluloses: Carboxymethylcellulose, methycellulose.
•Lipids: Bees wax, stearicacid, phospholipids.
•Proteins: Gelatin, albumin.

6. Microcapsules - Benefits
1- microorganism and enzyme immobilization:
- Enzymes have been encapsulated in cheeses to accelerate ripening and
flavor development.
- The enzymes are protected from low pH and high ionic strength in the
cheese.
• The encapsulation of microorganisms has been used to improve stability
of starter cultures
2- Protection against UV, heat, oxidation, acids, bases (e.g.colorants and
vitamins).
e.g. Vitamin A / monosodium glutamate, appearance (white) protection
(water, T, ligth)
3- Improved shelf life due to preventing degradative reactions (dehydration,
oxidation).
4- Masking of taste or odours.

7. Microcapsules - Benefits
5- Improved processing, texture and less wastage of ingredients.
• Control of hygroscopy
• enhance flowability and dispersibility
• dust free powder
• enhance solubility
6- Handling liquids as solids
7- Delivering Nutritious foods for children which provides them with much
needed vitamins and minerals during the growing age.
Microencapsulation could deliver the much needed ingredients in
children friendly and tasty way.
8- Enhance visual aspect and marketing concept.
9- Carbonless copy paper - A coating of microencapsulated colorless ink is
applied to the top sheet of paper, and a developer is applied to the
subsequent sheet. When pressure is applied by writing, the capsules
break and the ink reacts with the developer to produce the dark color of
the copy.

8. Microcapsules - Benefits
10- Textile industry makes use of microencapsulated materials to enhance
the properties of finished goods. One application increasingly utilized is
the incorporation of microencapsulated phase change materials (PCMs).
Phase change materials absorb and release heat in response to changes
in environmental temperatures. When temperatures rise, the phase
change material melts, absorbing excess heat, and feels cool.
Conversely, as temperatures fall, the PCM releases heat as it solidifies,
and feels warm.
This property of microencapsulated phase change materials can be
harnessed to increase the comfort level for users of sports equipment,
clothing, building materials, etc.

9. Microcapsules - Benefits
11- Pesticides are encapsulated to be released over time, allowing farmers
to apply the pesticides less amounts than requiring very highly
concentrated and toxic initial applications followed by repeated
applications to combat the loss of efficacy due to leaching,
evaporation, and degradation.
12- Ingredients in foods are encapsulated for several reasons
• Most flavorings are volatile; therefore encapsulation of
these components extends the shelf-life of these products
• Some ingredients are encapsulated to mask taste, such as nutrients
added to fortify a product without compromising the product's
intended taste.
• Alternatively, flavors are sometimes encapsulated to last longer, as in
chewing gum.

10. Microcapsules - Benefits
13- Controlled and targetted release of active ingredients.
• Many varieties of both oral and injected pharmaceutical
formulations are microencapsulated to release over longer periods
of time or at certain locations in the body.
• Aspirin, for example, can cause peptic ulcers and bleeding if doses
are introduced all at once. Therefore aspirin tablets are often
produced by compressing quantities of microcapsules that will
gradually release the aspirin through their shells, decreasing risk of
stomach damage.
14- Microencapsulation allows mixing of incompatible compounds.

11. .
Microcapsules - Technologies

12. Microcapsules - Processes with their relative particle size ranges
Physico - Chemical Processes Physico - mechanical Processes
Coacervation (2 - 1200 um) Spray-drying (5 - 5000 um)
Polymer-polymer incompatibility Fluidized- bed technology (20-
(0.5-1000 um) 1500 um)
Solvent evaporation (0.5-1000
Pan coating (600 - 5000 um)
um)
Encapsulation by supercritical fluid Spinning disc (5 - 1500 um)
Encapsulation by Polyelectrolyte Co-extrusion (250-2500
multilayer (0.02-20 um) um)
Hydrogel microsphere Chemical Processes
Interfacial polymerization (0.5-
Phase Inversion (0.5—5.0 um)
1000 um)
In situ polymerization (0.5-
Hot Melt (1—1000 um)
1100 um)

13. Microcapsules - Technologies
Coacervation Polymer-polymer Solvent
incompatibility Evaporation
(phase separation)

14. Microcapsules - Technologies
Rapid Expansion of Supercritical Fluids Hydrogel microspheres

15. Microcapsules - Technologies
Spray-Drying & spray-congealing

16. Microcapsules - Technologies
Fluidized-Bed Technology

17. Microcapsules - Technologies
Pan coating

18. Microcapsules - Technologies
Co-Extrusion

19. Microcapsules - Technologies
Spinning Disk

20. Applications in Textiles
In microencapsulation in general the number of commercial applications in
the textile industry continues to grow.
Microencapsulation processes as a means of imparting finishes and
properties on textiles for
• Developed textiles with new properties.
• New innovations and applications in Medical and Technical Textiles.
• Application in the area of cost-effectiveness required.
• Application where the technologies are not sufficient or not possible in
imparting some finishes.
• Increasing the durability of finishes.
Few Textile applications more interested in the area of
• Durable fragrances to textiles
• Skin softeners and other potential applications include,
• Insect repellents,
• Dyes,
• Vitamins,
• Antimicrobials,
• Phase change materials and in
• Specific medical applications, antibiotics, hormones and other drugs.

21. Applications in Textiles – Phase Change Material
The Technology was utilised in the early 1980s by the US - NASA with
the aim of managing the thermal barrier properties of garments, in
particular for use in space suits.
They encapsulated phase-change materials (PCMs) (e.g. nonadecane)
with the hope of reducing the impact of extreme variations in
temperature encountered by astronauts during their missions in space.
The potential was recognised where they can applied.
Outlast has exploited the technology in textile fibres and fabric coatings
and PCM capsules are now applied to all manner of materials.

22. Applications in Textiles – Phase Change Material
Applications in
Outdoor wear - (vests, thermals, snowsuits and trousers) and
In-house - {blankets, duvets, mattresses and pillowcases).
As well as being designed to combat cold, textiles containing PCMs also helps to
combat overheating, so overall the effect can be described as thermoregulation.
The microcapsules have walls less than 1 nm thick and are typically 20-40 nm in
diameter, with a PCM loading of 80-85%.
The small capsule size provides a relatively large surface area for heat transfer. Thus
the rate at which the PCM reacts to an external temperature changes is very rapid.
Accordis - UK, developed the technology of in-fibre incorporation of the Outlast
microcapsules, loading the fibre with 5-10% of microcapsules.
The process utilises late injection technology that was also used to produce the
antimicrobial fibre.
In this way the PCM is permanently locked within the fibre; there is no change
necessary in subsequent fibre processing (spinning, knitting, dyeing, etc.) and the fibre
exhibits its normal properties of drape, softness and strength.

23. Applications in Textiles – Fragrance Finishes
Fragrances to textiles has been carried out for many years in the form of fabric
conditioners in the wash and during tumble-dry-ing; all are designed to impart a fresh
aroma to the textile.
But the effect is relatively short-lived.
Numerous attempts have been made at adding fragrances directly to fibre and fabrics
but all fail to survive one or two wash cycles.
Only through microencapsulation are fra-grances able to remain on a garment during a
significant part of its lifetime.
Microencapsulation of essential oil flavours has led to many novelty applications,
particularly for children's garments, but it has also allowed exposure at home and in the
work place to the beneficial effects.
The majority of the work has been in microencapsulated 'scratch and sniff T-shirts and
in women's hosiery.
The nature of the microcap-sules is claimed that the durability can be (typically 8-20
cycles), depending on the active agent encapsulated, and the hosiery up to ten washes.
The capsules also survive drying in conventional tumble-dryers.

24. Applications in Textiles – Fragrance Finishes
Initial Applications:
Drawer liners, paper hand-kerchiefs, gift wrapping, stationary, greeting
cards, advertising brochures, books, cartons and labels.
Now, the basic technology of encapsulating fragrances in gelatin or
synthetic capsules, which protects the contents from evaporation,
oxidization and contamination.
The capsules range in size from 1 to 20 nm.
The technology allows a textile manufacturer to add a fragrance, vitamin,
moisturizer or even an insect repellent to all types of textile substrates.
Depending on application weights and the wash cycle used, up to 30
washes can be achieved without complete loss of fragrance.
In practice, the smaller the capsules the greater the covering of the
product and the longer the fragrance will last, as it takes longer for the
capsules to be ruptured by physical pressure.
Larger capsules release more fragrance when ruptured.

25. Applications in Textiles – Fragrance Finishes
The aqueous disper-sions of encapsulates, which can be applied by pad,
exhaustion or hydroextraction techniques to a wide variety of textile
substrates.
Durability to washing and handle (or feel) may be further im-proved by
incorporating suitable formaldehyde-free binders and softeners.
Microcapsules using melamine-formaldehyde systems containing
fra-grant oil, When attached to cotton these capsules were able to
survive over 15 wash cycles.
Microcapsules containing perfumes or cosmetic moisturisers that can be
padded, coated or sprayed onto a textile and held in place using an
acrylic or polyurethane binder.
Paper-like products have been produced con-taining microencapsulated
essential oils such as lavender, sage and rosemary for odour control
applications in shoe liners and insoles.

26. Applications in Textiles – Fragrance Finishes
For screen-printed application the encapsulates are simply mixed with
water-based, solvent-free inks or binders.
The capsule printing must be the last pass under a screen to avoid
damage to the walls by further screens.
Once printed, the fabric is then cured as with standard textile inks to
achieve a good bond to the fibres.
Usually a softener is also required, as unsoftened fabric containing
microcapsules can sometimes appear to be stiffened.
The capsules are colourless and can be applied over coloured fabric or
printed patterns without any adverse visible effects.
The fragrant effect can last for a year and a half. Gloves and socks are
also available that have fragrance-release properties and some
antibacterial effects, which the manufacturers claim to last for up to 25
wash cycles.

27. Applications in Textiles – Colour Changing
Poly chromic and thermo chromic microcapsules
Colour-changing technology has been generally applied to novelty
application such as stress testers, forehead thermometers and battery
testers.
New applications are now beginning to be seen in textiles, such as product
labelling, and medical and security applications.
In addition there is continued interest in novelty textiles for purposes such as
swimwear and T-shirts.
Two major types of colour-changing systems:
Thermochromatic: Alter colour in response to temperature, and
Photochromatic : Alter colour in response to UV light.
Both forms of colour-change material are produced in an encapsulated form
as microencapsulation helps to protect these sensitive chemicals from the
exter-nal environment.

28. Applications in Textiles – Colour Changing
Poly chromic and thermo chromic microcapsules
Today, manufacturers are able to make dyes that change colour at
specific temperatures for a given application.
e.g. colour changes can be initiated from the heat generated in response
to human contact.
Physiochemical and chemical processes such as Coacervation and
interfacial polymerization have been used to microencapsulate
photochromic and thermochromic systems.
To obtain satisfactory shelf life and durability on textiles, interfacial
polymerization techniques are nearly always adopted, which is the same
techniques used to produce textile fibres and films such as polyester,
nylon and polyurethane.
The most widely used system for microencapsulation of thermochromic
and photochromic inks involves urea or melamine-formaldehyde
systems.

29. Applications in Textiles – Flame Retardant
Fire retardants have been applied to many textile products.
But in certain cases they can affect the overall handle, reducing softness
and adversely affecting drape.
Microencapsulation has been used to overcome these problems for
example in fabrics used in military applications such as tentage.
Others have incorporated the microencapsulated fire retardants during
spinning of a polyester fibre for blending with cotton.

30. Applications in Textiles – Counterfeiting
In high added value textiles, and in branded and designer goods there is
great pressure to protect from illegal copying within the market-place.
Microencapsulation can be used to help with this problem by offering a
covert yet dis-tinctive marking system.
This system for combating textile counterfeiting utilizes microcapsules
containing a colour former or an activator applied to, for example, a
thread or a label.
The microcapsules adhere to the tex-tile and, depending on the type of
chemical within the capsules can be detected at a later date to check
authenticity.
Detection may be achieved directly using UV light or more likely by
using a solvent to break open the capsules, releasing the contents and
allowing a colour to develop.

31. Applications in Textiles – Liposomes
In recent years liposomes have been examined as a way of delivering dyes
to textiles in a cost- effective and environmentally sensitive way.
The liposomes used (for example, commercially available PC liposomes
from Transtechnics SL) were cost-effective, and no specific equipment or
skills were required to handle them within the dye house.
The results were excellent with pure wool and wool blends, and as the
temperature of dyeing could be reduced there was less fibre damage.
In their studies dye bath exhaustion was shown to greater than 90% at the
low temperature (80 °C) used resulting in significant saving in energy costs.
The impact of the dyeing process on the environment was also much
reduced with chemi-cal oxygen demand (COD) being reduced by about
1000 units.

32. Applications in Textiles – General
Encapsulated glycerol stearate and silk protein moisturizers for
application on bandages and support hosiery.
The material maintains comfort and skin quality through extensive
medical treatment where textiles are in direct contact with the skin.
Polypropylene nonwoven material for application as a cleaning/wiping
cloth containing microencapsulated octane, tung oil and paraffin oil as
cleaning solvents.
The cloths feel good in the hand and have very good cleaning properties.
The application of insecticides to textiles to combat dust mites and
insects such a mosquitoes, etc.,
Microencapsulation has been considered as a mechanism of retaining the
effect for significant periods without exposing the user to excessive
dosages of hazardous chemicals.
The use of alternative insecticidal compounds such as those found in
many essential oils and other plant extracts has made the production of
longlasting acaricide bed sheets possible.