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RHEOLOGICAL MODIFIERS

ALUMINIUM ADDITIVES

DURASTAB 36 
RHEOLOGY MODIFIER FOR PRINTING INKS

Durastab 36 is an organo-aluminium compound in a hydrocarbon base.

Durastab 36 is primarily used to develop body and reduce tack in printing ink vehicles. In addition it enhances pigment wetting, flow, setting, rate, gloss and reduces penetration and drying time as desirable side effect. These effects are brought about through chemical reaction of the gellant with the ink resin.

Durastab 36 is supplied as a pale yellow coloured liquid. It is readily soluble in the normal solvents used in the printing ink industry and is compatible with most oil, resin and vehicles like refined and bodied drying oils natural and synthetic oil soluble resins, alkyds, petroleum resins and mineral oils used in the printing ink industry. The use of highly polar solvents will be detrimental and is to be avoided as a viscosity adjustment measure of the base media.

The aluminium atom in Durastab 36 is extremely electrophilic and would react with both acid and alcohol termi (Present in ink media via an addition reaction even at atmospheric temperature resulting in increased MW of the system. At elevated temperatures the reactions are accelerated. These reactions result in viscosity increase leading to gelation in the extreme case if excess gellant is used. It should be noted that the resulting gel in a 3D network formed through covalent bonds and are fundamentally quite different from "mechanical gels" formed by aluminium soaps (octoate, stearate etc.) with hydrocarbon oils wherein a network of fibres held together by hydrogen bonding traps resin oil modecules and the networks (or gels) are broken reversibly and easily by small inputs of energy heat, shear forces etc.

Processing
The reaction of Durastab 36 with the vehicle is governed by a number of factors such as concentration, temperature, media characteristics like acid value and hydroxy1 value. Durastab 36 des not gel solvents, oils and consequently the presence of such non reactive ingredients retard the reaction rate and result in reduced structure modification. It is particularly recommended that laboratory trials establish process parameter precisely. Optimum conditions and quantities would vary with the particular media used, but the following is offered as a general recommendation. The order of addition, temperature, agitation time at temperatures and formulations are amongst the most important parameters. Initial evaluation should be made around 3% to 4% of Durastab 36 on the resin. At room temperature Durastab 36 may take upto 2 to 3 days to react fully with the media during which time agitation should be used periodically until the desired structure is achieved. A high temperature e.g. 90º - 120ºC say 10 to 20 minutes would suffice for a complete reaction. The addition of durastab 36 must be made at as low a temperature as possible (preferably at room temperature) and the temperature slowly increased under good agitation. The temperature is maintained for 10 to 20 minutes at 100º to 120º C before discharging. It is imperative that the gellant be thoroughly dispersed before reaction commences.

When hard resins are used to modify alkyd resins, higher processing temperatures may be required.

Storage Tanks and Manifolds

Dura Chemical Corporation Ltd.
Wakefield House, 11 Shri Shivsagar Ramgoolam Marg, 
Mumbai, Mh, India 400038 Tel: 91-22-22650861 / Fax: 91-22-22617352
Email for India : durachem@vsnl.com