Microencapsulation Technology (1): Definition of Microcapsulation

Microencapsulation can be defined as follows:

A compound called internal phase (IP) is “entrapped “ in a small sphere of 1 to
1500 microns average diameter size. The shell wall of the microcapsule can be
modified to allow the release of the compound as desired.

Our microencapsulation technology offers following advantages:
- Isolation of active ingredient
Isolation of a compound via microencapsulation process, brings to decrease
intrinsic toxicity, primary irritancy, potential smell…. Our technology allows mixing of
incompatible compounds.
- Protection of internal phase
Sensitive compounds can be isolated from outside, and be protected from oxygen,
moisture, chemicals, UV… This advantage is particularly appreciated to carry
sensitive ingredients such a PUFA, vitamins
- Controlled releasing system
Microencapsulation allows progressive releasing system of internal phase, offering
long lasting effects of active ingredients while increasing efficiency and decreasing
toxicity (pesticides, insect repellents).
- Presentation under solid or liquid form
Slurry of microcapsules is equivalent to a stable W/O emulsion, free of surfactants
and co-solvents. Under dry form, microcapsules presents a liquid compound under
stable powder.
- Visual effect
Big sizes coloured capsules (0.5 micron to 2mm) offers visual and attractive effects
in cosmetic and detergent formulations. Our macrocapsules may also contain
active ingredients such perfumes, vitamins, essential oils.

Microencapsulation Technology (2): Our Microcapsulation Tech

Our bio-tech experts started to research and develop the microcapsulation
successfully in the mid-period of the nineties of last century. It can be used in
manufacturing medicines and pesticides, also other fields, such as manufacturing
the active ingredient(s) of cosmetics, essences, textile and drugs for human coated
in microcapsules. The coating of the microcapsule is made from edible materials,
instead of polyamides. The technology of the microcapsule size between 100 to
900 nanometers is the most advanced. However, the grain size of our microcapsule
is between 400 and 500 nanometers, only about 2 to 5 μm. As is known to all, the
smaller its grain size, the more difficult it is manufactured, and the more advanced
the technology requires. Now our microcapsule technology is in the leading
position in China.

The characteristics are as follows:
1. Our technicians use the nonpoisonous and edible materials as the coatings of
microcapsules, which are able to be biodegradable, not to pollute the environment.

2. Especially, we can, by people, adjust and control the speed and time of
releasing the active ingredient in microcapsules. For example, we can control in 10
days to release out of the ingredient for vegetables with leaves; for cotton, in 25 to
90 days, and for forest pest control, in 250 days or more.

3. Microcapsule technology makes the active ingredient be encapsulated with.
Thus the microcapsule separates the ingredient from sunlight, oxygen, acids and
alkalis. The active ingredient volatilizes and degrades slowly through the
semipermeable holes on the microcapsule's shell and its effective duration can be
prolonged to 20 to 30 days, even longer. It can be said that it's unique, both higher
in effects of pest control and lower in costs.

4. The active ingredient after microencapsulation uses water as a deflocculant.
Water can't catch fire and is no toxicity. It is very safe.

5. The effect of pest control raises 5% to 20%. The reason is that after
microencapsulation, the active ingredient is relatively concentrates in the
microcapsules, and its concentration is far higher than one of water emulsion after
dispersion of emulsifiable solution or much higher than one of all the pesticides
taking water as a solvent. Once the bodies of insects touch and break the
microcapsules with high-enriched concentration, the liquid will penetrate their
epidermis into the bodies to make them be poisoned to death. For example, the
effect of Matrine microapsule CS is four times as high as Matrine AQUA without
microencapsulation. Thus, its dosage used per hectare is reduced and its spraying
times are decreased. Therefore, the customers save their production costs.

6. The particle size of the microcapsule is very small, only nanometer grade or μm
grade. But the microcapsule is strong in adhesive force so as to be able to stand
being beaten by wind and rain.

7. Low toxicity. Tested by big white mouse, the toxicity via mouth after
microencapsulation is generally only one twentieth to thirtieth before
microencapsulation, even much lower. It’s safer to human and domestic animals.

8. No chemicals
1) The core used is the edible materials.
2) All of the ingredients to control pests are alkaloids extracted from Chinese herbs.
3) The emulsifier is an edible sucrose ester.
4) Its medium is water.
5) Its antifreezer is ethandiol.
The product contains no sythetic chemical pesticides, such as esters of organo
phosphorous compounds, synthetic methrin and carboxylamine esters, etc.

Microencapsulation Technology (3): Fascinating Process

MICROENCAPSULATION is a fascinating process in which tiny droplets or particles
are wrapped with a protective coating yielding CAPSULES for countless
applications. In simple terms a capsule is a miniature container that protects its
contents from evaporation, oxidation and contamination until its release is triggered.

The size is always tailored to suit the end product and the relevant processes
involved in order to assure survival in hostile manufacturing conditions.

An area of one square centimetre (cm2) would contain one million capsules if
placed side by side in a standard coated paper application. This allows multiple
releases in the same area until finally all capsules are broken.

The most common applications are the coating of paper and board resulting in a
wide variety of end products such as; disposable handkerchiefs, drawer liners,
giftware, stationery, greeting cards, advertising, brochures, books, cartons and
labels etc.

The development of new methods and the ever increasing range of new polymeric
materials suitable for many different techniques in encapsulation are constantly
providing new applications.

This is resulting in new product opportunities driven by customer demand or
sometimes discovered as "spin-offs" resulting in a multitude of different projects.

Performance
Long term studies show that coated surfaces can remain intact for decades, the
oldest and still working example was printed in 1958! This enables savings in the
packaging costs, since no airtight wrapping is required.

Microencapsulation is the only cost effective and long lasting method in storing
volatile substances over a long period of time.
In advertising or in launching new products, encapsulation becomes a very
powerful tool by being invisible and coming to life at the slightest touch.
The rather impressive shelf life performance provides a key benefit organising
production of print runs which usually have to be planned some time ahead before
the actual article is inserted into a magazine for instance.

Microencapsulation Technology (4):
CONTROLLED RELEASE TECHNOLOGY AND
MICROENCAPSULATION CONSULTING

Controlled release technology is invaluable as a scientific tool for improving
performance and safety of chemicals. Active materials are encapsulated to form
barriers so that the active substance can be delivered at an optimum time and rate.
Usually specially designed polymers are used to make these barriers. Sometimes
adsorption inorganic compounds and complexes are used. Pharmaceutical
manufacturers use this technology as a method of measured, slow release of
drugs. Patent life can be extended by differentiating their products from previous
formulations. These aims can be achieved by:
1) Designing the barrier surrounding the active chemical to change its permeability
for the extracting fluid (water from the soil, acid from the stomach, etc.) without
extreme pain. The barrier material swells or slowly dissolves the extracting fluid.
2) Selection of an inorganic material which will adsorb the active material within its
layered or porous structure, thus again providing a less painful procedure for
extracting a fluid.
3) Designing a chemical which will complex the active material and release it at a
controlled rate under the right environmental conditions.
4) Controlling the chemistry of the active material to release only under certain
environmental conditions (pH or moisture content of the soil, pH of the stomach or
intestines).
Micro-encapsulation is an important sub-category of controlled release technology.
Active materials are encapsulated in micron sized capsules of barrier polymers.
These materials are designed to control the rate of release. The term "micro
encapsulation" is often confused for the much more inclusive "controlled release."  
Pharmaceutical Applications: The rate of delivery of a bioactive substance to a
target organism or reaction site is often critical. Key advantages to the use of this
technology are prolonged activity, fewer doses, fewer side effects and reduced
toxicity.  Too much of a medicinal ingested or injected all at once in order to have a
maintenance concentration can mean wasted material or toxic side effects. By
decreasing the dose rate to avoid these problems better efficacy results. A major
objective of the controlled release scientist is to determine the best speed of
release to obtain optimal performance. The success of theophylline as a bronco
dilator is due to its prolonged, carefully determined controlled release rate.
Agricultural Applications: Catastrophic damage has occurred as a result of
improper dosing of pesticides and fertilizers.  Controlled release formulations were
developed containing semipermeable barriers. These barriers allow the pesticides
or fertilizers to be leached out over an extended period of time reducing the
number of applications, improving crop yields and improving safety. Methyl
parathion (Trade name Penn-Cap M), a highly toxic insecticide, has been made
100 times safer without loss of efficacy by micro encapsulation.
Controlled Release Technology - What science does it involve? The application
may require release in different ways: a) constant release with time, b) release rate
diminishing with time and c) "burst release", where all of the active material is
released suddenly at a certain time, such as after the drug has passed through the
stomach into the intestines. Designing the barrier makes use of the solubilizing
rates, swelling rates, or permeability of the barrier polymer. The parameters in turn
may depend on the pH, moisture and temperature of the environment or the
chemical properties of the encapsulating polymer as well as its size, shape and
thickness.
Where to find the experts/consultants? The customizing of release rates is not a
skill taught in an university. It is learned by prolonged laboratory experience. Since
polymer science provides the most versatile barriers, the controlled release
scientist must have a good understanding of the biology and chemistry involved.
Consultants and employees who are skilled in controlled release are in great
demand due to the rapidly increasing number of new bioactive agents such as
proteins and peptides. TSHM has several experts who have contributed to this
science.

Microencapsulation Technology (5):
Microencapsulation Raises Profile of Pesticides

Health, safety, and environmental concerns are driving the use of
microencapsulation technology as a formulation option in pesticide markets,
reveals new research

The European Review of Plant Protection Products may well be playing a part in
increased use of microencapsulation technology in the pesticide sector, with the
market value of all products using the technology likely to double in the next five
years.
Gordon McManus, research analyst with Frost and Sullivan explains: "It might be
argued that as the European Review of Plant Protection Products actually starts to
pick up pace, with a realistic time frame for its completion in sight, the technology is
being used purely to defend some products and ensure their continued use on the
market.
However there are undoubtedly a number of other factors at play in its increased
use."
"Several new products using Capsule Suspension (CS) formulations have been
introduced in recent years and most of the market leaders have plans to introduce
more.
Advances in the technology, particularly on a large industrial scale, are resulting in
better quality encapsulations for lower cost, which is raising the profile of the
technology in the industry.
In addition, companies are reformulating products to protect them from generic
competition.
Patent extension is a possibility and if the whole market can be converted to using
the new formulations, it makes it harder for generic competitors to effectively
penetrate the market, with what might be seen as an out of date formulation."
For insecticides the most common problem in human toxicity and
microencapsulation can reduce the contact of active ingredients with humans -
particularly in applicator exposure tests.
For herbicides, environmental problems are more common and microencapsulation
can help reduce this effect by, for example, reducing run-off rates.
The improvements made in microencapsulation techniques - particularly in scaling
up to production levels means it is being accepted as a solution to the current
legislative issues.
Syngenta is undoubtedly the company showing most innovation in this field, with a
new 'quick release' CS formulation, which reduces toxicity to the applicator and the
environment, whilst providing the rapid knock-down effect of an EC formulation.
This is the first report to give an overview of the microencapsulation industry
throughout Europe with market share and competitor analysis.
Within the report there is a dedicated chapter which analyses the potential for each
application area in terms of relative market attractiveness, degree of competition
and relative market accessibility (eg an assessment of the barriers to entry) and
makes strategic recommendations for market participants.
The report is segmented into the following application areas: agrochemicals,
cosmetics ingredients, food ingredients, printing and paper applications,
adhesives, and textiles.

Microencapsulation Technology (6): Bibliography

Microencapsulation is the envelopment of small solid particles, liquid droplets, or
gas bubbles with a coating. The particles encapsulated are called the core, active
agent, active, internal phase, nucleus, payload, or fill. The coating surrounding the
core can consist of an organic polymer, hydrocolloid, sugar, wax, fat, metal, or
inorganic oxide.
The size of microencapsulated particles is of special importance. The size
generally ranges between 1 and 1000 micrometers. This finite size lends the
microcapsule to numerous applications in the pharmaceutical, agrochemical,
graphic arts and other industries.

Microcapsules have various possible structures, with the structure depending on
the desired application and encapsulation process. Three of the main capsule
structures are 1) embedded particles (or core) in the shell of the capsule, 2) a
continuous shell surrounding the core, and 3) multiple shells surrounding the core.
Capsules are characterized by the particle size, distribution, geometry, release
mechanism, storage stability, and other parameters. Thus, the materials chosen for
both the core and the surrounding shell play an important role in determining the
type of capsules obtained.

Manufacturing costs for capsules vary based on the coating material, solvent
system, equipment and labor required for encapsulation. Therefore, it is worthwhile
to thoroughly investigate the parameters which will have an impact on your
encapsulation.

Select Publications:

Thies, C. "Microencapsulation." Encyclopedia of Polymer Science and Engineering.
2nd ed. 1987, pp. 724-745.

Thies, C. "Microencapsulation: Mini Answer to Major Problems." Today's Chemist at
Work 3(10), 1994, pp. 40-45.

Benoit, J. -P., and Thies, C. "Microsphere Morphology." Microencapsulation:
Methods and Industrial Applications. Marcel Dekker: New York, 1996, pp. 133 - 154.

Thies, C. "A Survey of Microencapsulation Processes." Microencapsulation:
Methods and Industrial Applications. Marcel Dekker: New York, 1996, pp. 1 - 20.

Courteille, F., Benoit, J. -P., and Thies, C. "The Morphology of Progesterone-
loaded Polystyrene Microspheres." J. Controlled Release 30, 1994, pp. 17 - 26.

Neau, S. H., Goskonda, S. R., Upadrashta, S. M., Thies, C., Tripp, S. I.
"Encapsulation of a Volatile Oil by Ionic Gelation of Alginate." Am. J.
Pharmaceutical Education 57, 1993, pp. 126-129.

Svoboda, G. D., Zhou, J., Cheng, P. S., Asif, M., Distelrath, D. L., Thies, C.
"Theoretical Analysis of Microcapsule Mass Transport Behavior." J. Controlled
Release 20, 1992, pp. 195-200.

Thies, C. "Formation of Degradable Drug-loaded Microparticles by In-liquid
Drying." Microcapsules and Nanoparticles in Medicine and Pharmacy. CRC Press:
Boca Raton, 1992, Chap. 3.
Microcapsulation Technology
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