Rheological Additives for Crop Protection - Elementis Specialties

Rheological Additives
for Crop Protection

Contents
BENTONE
BENTONE
BENTONE ®
BENTONE BENTONE GEL
THIXCIN THIXCIN
® R
R
GEL ®
are are tradenames
tradenames of
of
ELEMENTIS ELEMENTIS SPECIALTIES
SPECIALTIES
Introduction Introduction
3
Crop Crop Protection Protection Agents and Rheology
Rheology
ELEMENTIS ELEMENTIS SPECIALTIES Rheological Additives Additives
6
Aqueous-Phase Aqueous-Phase Thickeners Thickeners
6
BENTONE BENTONE
® Hydrophilic Hydrophilic Clays Clays
6
Non-Aqueous-Phase Non-Aqueous-Phase Thickeners Thickeners
8
BENTONE BENTONE
® Organophilic Organophilic Clays Clays
8
THIXCIN THIXCIN
® Rheological
RheologicalAdditives
Rheological Additives 9
Product Product Application and and Selection Selection
10
Properties Properties and and Applications Applications Table Table
11
Incorporation
Incorporation Incorporation Guidelines Guidelines
12 12
4

Successful Crop protection formulations rely significantly on having the right
rheological properties. And choosing the best rheological additive is a key factor
in helping you create the best system.
ELEMENTIS Specialties provides you, the formulator, with valuable and proven
tools to do the job. Product stability and application characteristics, whether in
aqueous or non-aqueous formulations, are greatly enhanced by using
ELEMENTIS Specialties rheological additives. Thickeners based on clays and
polymers for the basis of the comprehensive ELEMENTIS Specialties pallette of
additives.
Introduction

Crop Protection Agents and Rheology
4
Fig 1
The rheological properties required of
crop protection formulations vary
according to the intended use of the
product.
Rheology is the study of flow. Flow
behaviour is measured in terms of its
viscosity. Viscosity is the resistance to
flow and defined as:
Viscosity =
Shear Stress
Shear Rate
Shear stress is the force per unit area
applied and shear rate is the resulting
velocity gradient. Crop protection agents
experience shear rates varying from
0.001s -1 , from gravitational forces, to
over 20,000s -1 , when sprayed. The way
the viscosity changes at varying shear
rates greatly influences the overall
product stability and performance. A
material which maintains a constant
viscosity, regardless of shear rate, has
Newtonian flow (Fig 1). Dilatant flow
(Fig 1) is a form where viscosity
increases with shear, sometimes
encountered in highly pigmented/filled
systems. Pseudoplastic flow (Fig 1),
also known as shear-thinning behaviour,
and typical of many commercial
systems, is when viscosity decreases
with increasing shear rate.
Flow may require a specific stress to be
initiated. This particular stress value is
known as the yield point. A system
having both shear-thinning and a yield
point can be described as having plastic
flow.

The rate of recovery of a system when
stress is removed is also very important.
When a shear-thinning system shows
delayed viscosity recovery, it is
described as thixotropic (Fig 2).
Shear-thinning flow is useful in modifying
product performance during application
(Fig 3). But, for suspension control, low
shear rate viscosity is all-important.
Suspension is best achieved by
developing a sufficiently high yield point
to withstand gravitational forces.
Viscosity can be temperature-
dependent. Correct choice of rheological
additive allows you to create the ideal
flow characteristics (Fig 1) and also
achieve thermostable rheology.
Fig 3
Crop Protection Agents and Rheology
Fig 2
5

ELEMENTIS SPECIALTIES Rheological Additives
Aqueous-Phase
Aqueous-Phase
Thickeners
Thickeners
6
ELEMENTIS Specialties rheological
additives can be broardly divided into
thickeners for aqueous and non-aqueous
systems. Clay and polymer based
additives provide the desired flow control
to water, oils or solvents to stabilise
formulations.
BENTONE BENTONE ® Hydrophilic
Hydrophilic Hydrophilic Clays
Clays
BENTONE ® MA, EW and LT additives
are produces from hectorite clay.
Hectorite is a natural material and is the
preferred clay for aqueous systems. It
offers high swelling and suspension
efficiency. Hectorite has a low iron
content - important in the presence of
iron-sensitive actives. Its inorganic
nature provides thermostable flow
control.
BENTONE ® MA and EW additives form
gels by producing an open,
3-dimensional network of the individual
clay platelets as shown in Figure 5.
BENTONE ® LT forms a similar network,
but it is strengthened by the presence of
a special cellulose, greatly enhancing
stability and thickening characteristics.
BENTONE ® LT is specially modified to
be stable over a broader range, pH 3-11,
and is the least sensitive to electrolytes.
The range of ELEMENTIS Specialties
products meeting EPA requirements can
be requested from our regulatory
department.
Non-ionic surfactants, if they are highly
ethoxylated, can adsorb onto the clay
surface. This rarely causes problems
either in flow control or activity of the
formulation.
Anionic surfactants can act as dispersing
agents and weaken the gel structure.
Alternatives that eliminate or minimise
any problems can normally be found.
However, cationic surfactants interact
strongly and should be avoided.
BENTONE® hydrophilic clays are used
alone or in combination with other
thickeners. Their use with xanthan gum
and other polysaccharides is particularly
effective in controlling suspension.

Fig 4
ELEMENTIS SPECIALTIES Rheology Additives
Open Open flocculated flocculated gel gel network
Incorporation
Incorporation
Hydrophilic Hydrophilic Hydrophilic Clays
Clays
Wetting Wetting - - Medium- to to high-shear mixing
mixing
- - Add clay clay to to water before before before addition addition of of other ingredients
ingredients
ingredients
- - Disperse at at moderate pH
Shear Shear - - Low shear shear shear (15 (>15 ms
ms -1 )
.. ..= .. = = Shorter mixing mixing mixing time time time (10 (10 - - - 15 15 mins mins) mins
Time Time - - 10 Minutes hydration hydration before before adding adding other other ingredients
ingredients
ingredients
Heat
Heat
- - - Water at at up to to 60°C (140°F) reduces the the hydration
hydration
time, but is is not not a necessity
necessity
It It is important important to to have only only clean clean water water present present at at the dispersion dispersion stage. stage.
stage.
Surfactants Surfactants or electrolytes electrolytes should should should not not be added added added until until dispersion dispersion is is complete
complete
7

ELEMENTIS SPECIALTIES Rheological Additives
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 -
-
Phase Phase Thickeners
Thickeners
Fig 5
8
Vegetable oils and solvents need
different approaches to achieve
suspension and flow control. The choice
BENTONE ® Organophilic Organophilic Clays
Clays
Clay (hectorite or bentonite) is reacted
with quaternary ammonium compounds
to produce organophilic clays. The
choice of clay and quaternary
ammonium compound determines the
degree of dispersibility and, more
importantly, the organoclay activity. For
example, BENTONE ® 34 and
BENTONE ® 38 additives are designed
for gelling medium- low polarity organic
liquids. Whereas BENTONE ® 27
additive is suitable for higher polarities.
is between organoclay or polymer based
thickeners.
The advantages gained from using
BENTONE ® organoclays are:
- Thermostable viscosity control
- Thixotropy
- Suspension control of actives
- Emulsion stabilisation
The presence of surfactants should be
avoided at the dispersion stage. Correct
incorporation (Fig 6) requires the use of
high-shear dispersion equipment and the
addition of a chemical activator.
However, easy-dispersing BENTONE
SD ® rheological additives, which do not
require activation, are also available.

ELEMENTIS SPECIALTIES Rheological Additives
THIXCIN ® Rheological Rheological Additives
Additives
THIXCIN ® E and THIXCIN ® R additives
are castor oil derivatives. Compared to
organoclays they impart a more
thixotropic flow to aliphatic materials and
are useful in high viscosity systems to
prevent running. Additionally they can
Fig 6
act as binders in granulated and
pelletised systems.
THIXCIN® additives are incorporated
(Fig 6) using high-shear equipment and
working within specific temperature
ranges.
Recommended
Recommended Recommended processing processing temperature temperature ranges ranges ranges in in solvent-borne
solvent-borne
systems systems using high-speed high-speed dispersion dispersion equipment equipment:
equipment
Product Product Aliphatic Aliphatic Aromatic Aromatic Oxygenated
Oxygenated
THIXCIN THIXCIN
® E
THIXCIN THIXCIN
® R
35°C 35°C to to 55°C
Not
Not
(95°F (95°F to to 140°F)
recommended
recommended
35°C 35°C to to 55°C
Not
Not
(95°F (95°F to to 140°F)
recommended
recommended
Activation Activation of of of powder -type -type organic organic rheological
rheological rheological additives additives
additives
Not
Not
recommended
recommended
Not
Not
recommended
recommended
9

Product Application and Selection
10
Crop protection formulations of various
types can benefint from ELEMENTIS
Specialties additives. The advantages of
flow control are not confined to
suspension alone. In addition the
hectorite clay surface provides a highly
adsorbent substrate for dry-based
formulations.
Choice of additive may also be
determined by the market the crop
protection agent is to be sold in, for
example countries adopting the EPA
Products
Products
Additives Additives Additives for Water
BENTONE BENTONE BENTONE
® MA
BENTONE BENTONE
® EW
EW
BENTONE BENTONE
® LT
LT
Additives Additives Additives for
Solvents Solvents/Oil
Solvents
Oil
BENTONE BENTONE
® 34
BENTONE BENTONE
® 38
THIXCIN THIXCIN
® E
THIXCIN THIXCIN
® R
Section Section Section (c)
Section Section Section (d)
Section Section (e)
rulings. Many ELEMENTIS Specialties
additives comply with certain EPA
requirements.
However, non-EPA markets can utilise
the larger range of ELEMENTIS
Specialties additives. Details of which
can be obtained from ELEMENTIS
Specialties.
The following products comply with EPA
requirements as inert ingredients exempt
from the requirements of a tolerance
under 40 CFR 180.1001 (c), (d) or (e):
Exempt Exempt from from tolerance tolerance requirement
requirement
EPA EPA EPA 40 40 CFR 180.1001
180.1001
(c) (d) (e)
Pesticide Pesticide formulations formulations applied applied to
to
growing growing crops crops or or to to raw agriculture
agriculture
commodities commodities after after harvest harvest
Pesticide Pesticide formulations formulations applied applied to
to
growing growing crops crops only
only
Pesticide Pesticide Pesticide formulations formulations applied applied to
to
animals
animals

ELEMENTIS
ELEMENTISSpecialties
Specialties SpecialtiesAdditives Additives
Properties
Properties
Aqueous-Phase
Aqueous-Phase
Thickeners Thickeners
Non-Aqueous-Phase
Non-Aqueous-Phase
Thickeners
Thickeners
imparted
imparted by
by ELEMENTIS
ELEMENTIS Specialties
Specialties products
products
Highly Recommended
Recommended
BENTONE ® MA
BENTONE ® EW
BENTONE ® LT
BENTONE ® 27
BENTONE ® 34
BENTONE ® 38
THIXCIN ® E
THIXCIN ® R
Properties and Applications Table
Solutions
Suspensions
Suspensions
Aqueous
Non-Aqueous
Suspo-Emulsions
Applications
Applications
Suspension Suspension
X X X X X
Thickening Thickening
X X X X X X X X
Flow FlowControl
Control Control
X X X X X X X X
Emulsion Emulsion Stability Stability
X X
Thermal Thermal Stability X X X X X X
Increased IncreasedResiduality
Increased Residuality X X X X X X X
Drift Drift Control X X X X X X X
Adsorbent AdsorbentSubstrate
Adsorbent Substrate X X
Crystal CrystalGrowth
Crystal CrystalGrowth
GrowthInhibition
Growth Inhibition X X X X
Emulsions
Emulsifiable Concentrates
Ultra Low Volume (ULV's)
Wettable Granules/Powders
Granules/Dusts
11

Product Application and Selection
Shear Development
Generic Type
12
Low Low Medium Medium - High Medium - High Very High
Paddle Propeller Planetary Rotor/Stator Impeller Homogeniser
BENTONE ® MA, BENTONE ® EW and BENTONE ® LT additives - powders needing high-energy mixing
Conditions
Order of addition
Special Factors
BENTONE ® 27, BENTONE ® 34 and BENTONE ® 38 additives - powders needing high-energy mixing
Conditions
Order of addition
Special Factors
Suitable only for BENTONE ® EW
additive. Use highest speeds
(>3000 rpm)
Clean water and rheological additive only.
Suitable for BENTONE ® MA, BENTONE ® EW and
BENTONE ® LT additives.
Use highest speeds and carefully observe optimum
mixer/vessel configuration
Avoid addition of surfactants or electrolytes until dispersion completed.
BENTONE ® EW < 5%
pH of water neutral. Sift clay in
gradually. Add defoamers, if
needed, only after dispersion
completed.
BENTONE ® MA < 10%
BENTONE ® EW < 5%
BENTONE ® LT < 4%
pH of water neutral.
Sift clay in gradually.
Unsuitable - insufficient shear. Suitable for BENTONE ® 27, BENTONE ® 34 and
BENTONE ® 38 additives.
N/A
Use highest speeds and carefully observe optimum
mixer/vessel configuration
Oil or solvent alone.
Add organoclay and disperse.
Add polar activator and continue dispersing.
N/A Ensure full wetting achieved before activation.
Use optimum level of polar activator.
Avoid the presence of surfactants until after activation.
Suitable for
BENTONE ® MA,
BENTONE ® EW
and BENTONE ®
LT additives.
Recommended
for BENTONE ®
27, and
BENTONE ® 38
additives.

Before using any of our products please consult our Safety Data Sheets.
The information in this publication is, to the best of our knowledge, true and accurate, but since the conditions of use are beyond our
control, no warranty is given or to be implied in respect of such information. In every case, caution must be exercised to avoid
violation or infringement of statutory obligations and any rights belonging to a third party. We are, at all time, willing to study customers’
specific outlets involving Our products in order to enable their most effective use.
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