Rheological Additives for Crop Protection - Elementis Specialties
Rheological Additives for Crop Protection - Elementis Specialties
Rheological Additives for Crop Protection - Elementis Specialties
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<strong>Rheological</strong> <strong>Additives</strong><br />
<strong>for</strong> <strong>Crop</strong> <strong>Protection</strong>
Contents<br />
BENTONE<br />
BENTONE<br />
BENTONE ®<br />
BENTONE BENTONE GEL<br />
THIXCIN THIXCIN<br />
® R<br />
R<br />
GEL ®<br />
are are tradenames<br />
tradenames of<br />
of<br />
ELEMENTIS ELEMENTIS SPECIALTIES<br />
SPECIALTIES<br />
Introduction Introduction<br />
3<br />
<strong>Crop</strong> <strong>Crop</strong> <strong>Protection</strong> <strong>Protection</strong> Agents and Rheology<br />
Rheology<br />
ELEMENTIS ELEMENTIS SPECIALTIES <strong>Rheological</strong> <strong>Additives</strong> <strong>Additives</strong><br />
6<br />
Aqueous-Phase Aqueous-Phase Thickeners Thickeners<br />
6<br />
BENTONE BENTONE<br />
® Hydrophilic Hydrophilic Clays Clays<br />
6<br />
Non-Aqueous-Phase Non-Aqueous-Phase Thickeners Thickeners<br />
8<br />
BENTONE BENTONE<br />
® Organophilic Organophilic Clays Clays<br />
8<br />
THIXCIN THIXCIN<br />
® <strong>Rheological</strong><br />
<strong>Rheological</strong><strong>Additives</strong><br />
<strong>Rheological</strong> <strong>Additives</strong> 9<br />
Product Product Application and and Selection Selection<br />
10<br />
Properties Properties and and Applications Applications Table Table<br />
11<br />
Incorporation<br />
Incorporation Incorporation Guidelines Guidelines<br />
12 12<br />
4
Successful <strong>Crop</strong> protection <strong>for</strong>mulations rely significantly on having the right<br />
rheological properties. And choosing the best rheological additive is a key factor<br />
in helping you create the best system.<br />
ELEMENTIS <strong>Specialties</strong> provides you, the <strong>for</strong>mulator, with valuable and proven<br />
tools to do the job. Product stability and application characteristics, whether in<br />
aqueous or non-aqueous <strong>for</strong>mulations, are greatly enhanced by using<br />
ELEMENTIS <strong>Specialties</strong> rheological additives. Thickeners based on clays and<br />
polymers <strong>for</strong> the basis of the comprehensive ELEMENTIS <strong>Specialties</strong> pallette of<br />
additives.<br />
Introduction
<strong>Crop</strong> <strong>Protection</strong> Agents and Rheology<br />
4<br />
Fig 1<br />
The rheological properties required of<br />
crop protection <strong>for</strong>mulations vary<br />
according to the intended use of the<br />
product.<br />
Rheology is the study of flow. Flow<br />
behaviour is measured in terms of its<br />
viscosity. Viscosity is the resistance to<br />
flow and defined as:<br />
Viscosity =<br />
Shear Stress<br />
Shear Rate<br />
Shear stress is the <strong>for</strong>ce per unit area<br />
applied and shear rate is the resulting<br />
velocity gradient. <strong>Crop</strong> protection agents<br />
experience shear rates varying from<br />
0.001s -1 , from gravitational <strong>for</strong>ces, to<br />
over 20,000s -1 , when sprayed. The way<br />
the viscosity changes at varying shear<br />
rates greatly influences the overall<br />
product stability and per<strong>for</strong>mance. A<br />
material which maintains a constant<br />
viscosity, regardless of shear rate, has<br />
Newtonian flow (Fig 1). Dilatant flow<br />
(Fig 1) is a <strong>for</strong>m where viscosity<br />
increases with shear, sometimes<br />
encountered in highly pigmented/filled<br />
systems. Pseudoplastic flow (Fig 1),<br />
also known as shear-thinning behaviour,<br />
and typical of many commercial<br />
systems, is when viscosity decreases<br />
with increasing shear rate.<br />
Flow may require a specific stress to be<br />
initiated. This particular stress value is<br />
known as the yield point. A system<br />
having both shear-thinning and a yield<br />
point can be described as having plastic<br />
flow.
The rate of recovery of a system when<br />
stress is removed is also very important.<br />
When a shear-thinning system shows<br />
delayed viscosity recovery, it is<br />
described as thixotropic (Fig 2).<br />
Shear-thinning flow is useful in modifying<br />
product per<strong>for</strong>mance during application<br />
(Fig 3). But, <strong>for</strong> suspension control, low<br />
shear rate viscosity is all-important.<br />
Suspension is best achieved by<br />
developing a sufficiently high yield point<br />
to withstand gravitational <strong>for</strong>ces.<br />
Viscosity can be temperature-<br />
dependent. Correct choice of rheological<br />
additive allows you to create the ideal<br />
flow characteristics (Fig 1) and also<br />
achieve thermostable rheology.<br />
Fig 3<br />
<strong>Crop</strong> <strong>Protection</strong> Agents and Rheology<br />
Fig 2<br />
5
ELEMENTIS SPECIALTIES <strong>Rheological</strong> <strong>Additives</strong><br />
Aqueous-Phase<br />
Aqueous-Phase<br />
Thickeners<br />
Thickeners<br />
6<br />
ELEMENTIS <strong>Specialties</strong> rheological<br />
additives can be broardly divided into<br />
thickeners <strong>for</strong> aqueous and non-aqueous<br />
systems. Clay and polymer based<br />
additives provide the desired flow control<br />
to water, oils or solvents to stabilise<br />
<strong>for</strong>mulations.<br />
BENTONE BENTONE ® Hydrophilic<br />
Hydrophilic Hydrophilic Clays<br />
Clays<br />
BENTONE ® MA, EW and LT additives<br />
are produces from hectorite clay.<br />
Hectorite is a natural material and is the<br />
preferred clay <strong>for</strong> aqueous systems. It<br />
offers high swelling and suspension<br />
efficiency. Hectorite has a low iron<br />
content - important in the presence of<br />
iron-sensitive actives. Its inorganic<br />
nature provides thermostable flow<br />
control.<br />
BENTONE ® MA and EW additives <strong>for</strong>m<br />
gels by producing an open,<br />
3-dimensional network of the individual<br />
clay platelets as shown in Figure 5.<br />
BENTONE ® LT <strong>for</strong>ms a similar network,<br />
but it is strengthened by the presence of<br />
a special cellulose, greatly enhancing<br />
stability and thickening characteristics.<br />
BENTONE ® LT is specially modified to<br />
be stable over a broader range, pH 3-11,<br />
and is the least sensitive to electrolytes.<br />
The range of ELEMENTIS <strong>Specialties</strong><br />
products meeting EPA requirements can<br />
be requested from our regulatory<br />
department.<br />
Non-ionic surfactants, if they are highly<br />
ethoxylated, can adsorb onto the clay<br />
surface. This rarely causes problems<br />
either in flow control or activity of the<br />
<strong>for</strong>mulation.<br />
Anionic surfactants can act as dispersing<br />
agents and weaken the gel structure.<br />
Alternatives that eliminate or minimise<br />
any problems can normally be found.<br />
However, cationic surfactants interact<br />
strongly and should be avoided.<br />
BENTONE® hydrophilic clays are used<br />
alone or in combination with other<br />
thickeners. Their use with xanthan gum<br />
and other polysaccharides is particularly<br />
effective in controlling suspension.
Fig 4<br />
ELEMENTIS SPECIALTIES Rheology <strong>Additives</strong><br />
Open Open flocculated flocculated gel gel network<br />
Incorporation<br />
Incorporation<br />
Hydrophilic Hydrophilic Hydrophilic Clays<br />
Clays<br />
Wetting Wetting - - Medium- to to high-shear mixing<br />
mixing<br />
- - Add clay clay to to water be<strong>for</strong>e be<strong>for</strong>e be<strong>for</strong>e addition addition of of other ingredients<br />
ingredients<br />
ingredients<br />
- - Disperse at at moderate pH<br />
Shear Shear - - Low shear shear shear (15 (>15 ms<br />
ms -1 )<br />
.. ..= .. = = Shorter mixing mixing mixing time time time (10 (10 - - - 15 15 mins mins) mins<br />
Time Time - - 10 Minutes hydration hydration be<strong>for</strong>e be<strong>for</strong>e adding adding other other ingredients<br />
ingredients<br />
ingredients<br />
Heat<br />
Heat<br />
- - - Water at at up to to 60°C (140°F) reduces the the hydration<br />
hydration<br />
time, but is is not not a necessity<br />
necessity<br />
It It is important important to to have only only clean clean water water present present at at the dispersion dispersion stage. stage.<br />
stage.<br />
Surfactants Surfactants or electrolytes electrolytes should should should not not be added added added until until dispersion dispersion is is complete<br />
complete<br />
7
ELEMENTIS SPECIALTIES <strong>Rheological</strong> <strong>Additives</strong><br />
N N oo o o nn n n - - A A qq q q uu u u ee e e oo o o uu u u s s -<br />
-<br />
Phase Phase Thickeners<br />
Thickeners<br />
Fig 5<br />
8<br />
Vegetable oils and solvents need<br />
different approaches to achieve<br />
suspension and flow control. The choice<br />
BENTONE ® Organophilic Organophilic Clays<br />
Clays<br />
Clay (hectorite or bentonite) is reacted<br />
with quaternary ammonium compounds<br />
to produce organophilic clays. The<br />
choice of clay and quaternary<br />
ammonium compound determines the<br />
degree of dispersibility and, more<br />
importantly, the organoclay activity. For<br />
example, BENTONE ® 34 and<br />
BENTONE ® 38 additives are designed<br />
<strong>for</strong> gelling medium- low polarity organic<br />
liquids. Whereas BENTONE ® 27<br />
additive is suitable <strong>for</strong> higher polarities.<br />
is between organoclay or polymer based<br />
thickeners.<br />
The advantages gained from using<br />
BENTONE ® organoclays are:<br />
- Thermostable viscosity control<br />
- Thixotropy<br />
- Suspension control of actives<br />
- Emulsion stabilisation<br />
The presence of surfactants should be<br />
avoided at the dispersion stage. Correct<br />
incorporation (Fig 6) requires the use of<br />
high-shear dispersion equipment and the<br />
addition of a chemical activator.<br />
However, easy-dispersing BENTONE<br />
SD ® rheological additives, which do not<br />
require activation, are also available.
ELEMENTIS SPECIALTIES <strong>Rheological</strong> <strong>Additives</strong><br />
THIXCIN ® <strong>Rheological</strong> <strong>Rheological</strong> <strong>Additives</strong><br />
<strong>Additives</strong><br />
THIXCIN ® E and THIXCIN ® R additives<br />
are castor oil derivatives. Compared to<br />
organoclays they impart a more<br />
thixotropic flow to aliphatic materials and<br />
are useful in high viscosity systems to<br />
prevent running. Additionally they can<br />
Fig 6<br />
act as binders in granulated and<br />
pelletised systems.<br />
THIXCIN® additives are incorporated<br />
(Fig 6) using high-shear equipment and<br />
working within specific temperature<br />
ranges.<br />
Recommended<br />
Recommended Recommended processing processing temperature temperature ranges ranges ranges in in solvent-borne<br />
solvent-borne<br />
systems systems using high-speed high-speed dispersion dispersion equipment equipment:<br />
equipment<br />
Product Product Aliphatic Aliphatic Aromatic Aromatic Oxygenated<br />
Oxygenated<br />
THIXCIN THIXCIN<br />
® E<br />
THIXCIN THIXCIN<br />
® R<br />
35°C 35°C to to 55°C<br />
Not<br />
Not<br />
(95°F (95°F to to 140°F)<br />
recommended<br />
recommended<br />
35°C 35°C to to 55°C<br />
Not<br />
Not<br />
(95°F (95°F to to 140°F)<br />
recommended<br />
recommended<br />
Activation Activation of of of powder -type -type organic organic rheological<br />
rheological rheological additives additives<br />
additives<br />
Not<br />
Not<br />
recommended<br />
recommended<br />
Not<br />
Not<br />
recommended<br />
recommended<br />
9
Product Application and Selection<br />
10<br />
<strong>Crop</strong> protection <strong>for</strong>mulations of various<br />
types can benefint from ELEMENTIS<br />
<strong>Specialties</strong> additives. The advantages of<br />
flow control are not confined to<br />
suspension alone. In addition the<br />
hectorite clay surface provides a highly<br />
adsorbent substrate <strong>for</strong> dry-based<br />
<strong>for</strong>mulations.<br />
Choice of additive may also be<br />
determined by the market the crop<br />
protection agent is to be sold in, <strong>for</strong><br />
example countries adopting the EPA<br />
Products<br />
Products<br />
<strong>Additives</strong> <strong>Additives</strong> <strong>Additives</strong> <strong>for</strong> Water<br />
BENTONE BENTONE BENTONE<br />
® MA<br />
BENTONE BENTONE<br />
® EW<br />
EW<br />
BENTONE BENTONE<br />
® LT<br />
LT<br />
<strong>Additives</strong> <strong>Additives</strong> <strong>Additives</strong> <strong>for</strong><br />
Solvents Solvents/Oil<br />
Solvents<br />
Oil<br />
BENTONE BENTONE<br />
® 34<br />
BENTONE BENTONE<br />
® 38<br />
THIXCIN THIXCIN<br />
® E<br />
THIXCIN THIXCIN<br />
® R<br />
Section Section Section (c)<br />
Section Section Section (d)<br />
Section Section (e)<br />
rulings. Many ELEMENTIS <strong>Specialties</strong><br />
additives comply with certain EPA<br />
requirements.<br />
However, non-EPA markets can utilise<br />
the larger range of ELEMENTIS<br />
<strong>Specialties</strong> additives. Details of which<br />
can be obtained from ELEMENTIS<br />
<strong>Specialties</strong>.<br />
The following products comply with EPA<br />
requirements as inert ingredients exempt<br />
from the requirements of a tolerance<br />
under 40 CFR 180.1001 (c), (d) or (e):<br />
Exempt Exempt from from tolerance tolerance requirement<br />
requirement<br />
EPA EPA EPA 40 40 CFR 180.1001<br />
180.1001<br />
(c) (d) (e)<br />
Pesticide Pesticide <strong>for</strong>mulations <strong>for</strong>mulations applied applied to<br />
to<br />
growing growing crops crops or or to to raw agriculture<br />
agriculture<br />
commodities commodities after after harvest harvest<br />
Pesticide Pesticide <strong>for</strong>mulations <strong>for</strong>mulations applied applied to<br />
to<br />
growing growing crops crops only<br />
only<br />
Pesticide Pesticide Pesticide <strong>for</strong>mulations <strong>for</strong>mulations applied applied to<br />
to<br />
animals<br />
animals
ELEMENTIS<br />
ELEMENTIS<strong>Specialties</strong><br />
<strong>Specialties</strong> <strong>Specialties</strong><strong>Additives</strong> <strong>Additives</strong><br />
Properties<br />
Properties<br />
Aqueous-Phase<br />
Aqueous-Phase<br />
Thickeners Thickeners<br />
Non-Aqueous-Phase<br />
Non-Aqueous-Phase<br />
Thickeners<br />
Thickeners<br />
imparted<br />
imparted by<br />
by ELEMENTIS<br />
ELEMENTIS <strong>Specialties</strong><br />
<strong>Specialties</strong> products<br />
products<br />
Highly Recommended<br />
Recommended<br />
BENTONE ® MA<br />
BENTONE ® EW<br />
BENTONE ® LT<br />
BENTONE ® 27<br />
BENTONE ® 34<br />
BENTONE ® 38<br />
THIXCIN ® E<br />
THIXCIN ® R<br />
Properties and Applications Table<br />
Solutions<br />
Suspensions<br />
Suspensions<br />
Aqueous<br />
Non-Aqueous<br />
Suspo-Emulsions<br />
Applications<br />
Applications<br />
Suspension Suspension<br />
X X X X X<br />
Thickening Thickening<br />
X X X X X X X X<br />
Flow FlowControl<br />
Control Control<br />
X X X X X X X X<br />
Emulsion Emulsion Stability Stability<br />
X X<br />
Thermal Thermal Stability X X X X X X<br />
Increased IncreasedResiduality<br />
Increased Residuality X X X X X X X<br />
Drift Drift Control X X X X X X X<br />
Adsorbent AdsorbentSubstrate<br />
Adsorbent Substrate X X<br />
Crystal CrystalGrowth<br />
Crystal CrystalGrowth<br />
GrowthInhibition<br />
Growth Inhibition X X X X<br />
Emulsions<br />
Emulsifiable Concentrates<br />
Ultra Low Volume (ULV's)<br />
Wettable Granules/Powders<br />
Granules/Dusts<br />
11
Product Application and Selection<br />
Shear Development<br />
Generic Type<br />
12<br />
Low Low Medium Medium - High Medium - High Very High<br />
Paddle Propeller Planetary Rotor/Stator Impeller Homogeniser<br />
BENTONE ® MA, BENTONE ® EW and BENTONE ® LT additives - powders needing high-energy mixing<br />
Conditions<br />
Order of addition<br />
Special Factors<br />
BENTONE ® 27, BENTONE ® 34 and BENTONE ® 38 additives - powders needing high-energy mixing<br />
Conditions<br />
Order of addition<br />
Special Factors<br />
Suitable only <strong>for</strong> BENTONE ® EW<br />
additive. Use highest speeds<br />
(>3000 rpm)<br />
Clean water and rheological additive only.<br />
Suitable <strong>for</strong> BENTONE ® MA, BENTONE ® EW and<br />
BENTONE ® LT additives.<br />
Use highest speeds and carefully observe optimum<br />
mixer/vessel configuration<br />
Avoid addition of surfactants or electrolytes until dispersion completed.<br />
BENTONE ® EW < 5%<br />
pH of water neutral. Sift clay in<br />
gradually. Add defoamers, if<br />
needed, only after dispersion<br />
completed.<br />
BENTONE ® MA < 10%<br />
BENTONE ® EW < 5%<br />
BENTONE ® LT < 4%<br />
pH of water neutral.<br />
Sift clay in gradually.<br />
Unsuitable - insufficient shear. Suitable <strong>for</strong> BENTONE ® 27, BENTONE ® 34 and<br />
BENTONE ® 38 additives.<br />
N/A<br />
Use highest speeds and carefully observe optimum<br />
mixer/vessel configuration<br />
Oil or solvent alone.<br />
Add organoclay and disperse.<br />
Add polar activator and continue dispersing.<br />
N/A Ensure full wetting achieved be<strong>for</strong>e activation.<br />
Use optimum level of polar activator.<br />
Avoid the presence of surfactants until after activation.<br />
Suitable <strong>for</strong><br />
BENTONE ® MA,<br />
BENTONE ® EW<br />
and BENTONE ®<br />
LT additives.<br />
Recommended<br />
<strong>for</strong> BENTONE ®<br />
27, and<br />
BENTONE ® 38<br />
additives.
Be<strong>for</strong>e using any of our products please consult our Safety Data Sheets.<br />
The in<strong>for</strong>mation in this publication is, to the best of our knowledge, true and accurate, but since the conditions of use are beyond our<br />
control, no warranty is given or to be implied in respect of such in<strong>for</strong>mation. In every case, caution must be exercised to avoid<br />
violation or infringement of statutory obligations and any rights belonging to a third party. We are, at all time, willing to study customers’<br />
specific outlets involving Our products in order to enable their most effective use.<br />
© Copyright 2009, <strong>Elementis</strong> <strong>Specialties</strong>, Inc. All rights reserved.<br />
Copying and/or downloading of this document or in<strong>for</strong>mation therein <strong>for</strong> republication is not allowed unless prior written agreement is<br />
obtained from <strong>Elementis</strong> <strong>Specialties</strong>, Inc.<br />
® Registered trademark of <strong>Elementis</strong> <strong>Specialties</strong>, Inc.<br />
For more details please contact:<br />
AMERICAS <strong>Elementis</strong> <strong>Specialties</strong><br />
P.O. Box 700<br />
Hightstown<br />
New Jersey 08520<br />
USA<br />
Tel: +1.609.443 2500<br />
Fax: +1.609.443 2446<br />
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50933 Cologne<br />
Germany<br />
Tel: +49.221.485.2900<br />
Fax: +49.221.485.2910