PARALOID™ K120N-K120ND Acrylic Processing Aid
Over 35 years ago, Dow introduced the first all-acrylic processing aid, pioneering a technological breakthrough. This addition has made rigid PVC processing possible, and therefore a viable material for many new applications.
Today, PARALOID K120N and K120ND are industry standards, used in the production of bottles, in film/sheet applications and in the construction industry, representing a high proportion of the total sales of the world’s acrylic processing aids for vinyls.
In addition to faster fusion, PARALOID acrylic processing aids offer many attractive rheological features and improve the quality and finish of the product. These benefits will be evident from the results of the tests shown in this brochure.
By dramatically shortening the fusion time, PARALOID K120N and K120ND can increase production output and improve yield.
Improved fusion also permits a broader range of processing temperatures and conditions. Other processing benefits include improved melt-elasticity and reduction of plate-out and melt fracture.
PARALOID acrylic processing aids improve product quality in terms of surface gloss and finish, more even thickness and weight, weld-line strength, tensile strength and impact efficiency.
These benefits are obtained with the use of both PARALOID K120N and K120ND. In addition, PARALOID K120N and K120ND comply with the FDA and most European food packaging regulations.* PARALOID K120ND is generally chosen by manufacturers requiring excellent dispersibility and good optical properties, under low-shear processing conditions.
The PARALOID K120N/K120ND production process has obtained the ISO 9002 quality assurance certification.
* For further information on food contact compliance of our products, please refer to the local Dow Sales Subsidary.
Performance in Processing
Using a PARALOID processing aid to change the polymer melt rheology provides the processors with a material that adapts to wide operational conditions and allows increased throughput. The addition of these products to PVC formulations improves the fusion behaviour and results in a more homogeneous melt. The high molecular weight of the processing aids also results in higher melt strength and higher rupture stress.
PARALOID processing aids give a significant improvement to fusion, with faster fusion speed and higher fusion torque.
Brabender Rheology Test (Sn-Stabilised)
This test shows the effect of changing rotor speed on rheology, with a bowl temperature of 150°C.
Test conditions: Brabender bowl W50, stock weight 55g.
This test shows the effect of changing bowl temperature on rheology, with a rotor speed of 40 RPM.
Brabender Rheology Test (Pb-Stabilised)
Similar results are found in Pb-stabilised formulations.
Test conditions: 160°C, 50 RPM, 57g, W50 Brabender bowl
Melt Strength and Homogenisation
The marked increases in melt strength and homogenisation provided by the addition of PARALOID K120N and K120ND translate into reduced melt fracture and more detailed thermoforming, giving deeper draws without tearing.
Rheotens Melt Elongational Test (Sn-Stabilised)
The addition of PARALOID processing aids significantly improves the elongational properties, resulting in better thermoforming and blow moulding. The increased stress at break translates into reduced melt fracture and improved surface finish.
The Rheotens test, which measures elongation and stress of polymer melts, characterises melt elastic properties directly from the extruder, and predicts the performance of compounds in the molten state.
These tests, on Ca/Zn and Sn formulations, show the effect of PARALOID processing aids on flow time and weight, which translates into better control of wall thickness.
Test conditions: Two-roll at 200°C 26/20 RPM
The addition of PARALOID K120N and K120ND processing aids does not adversely affect heat stability.
Dynamic Heat Stability (Ca/Zn-Stabilised)
Typical Powder Properties
Performance in Finished Products
PARALOID processing aids, in addition to enhancing the performance of processing, give a clear benefit to the finished products. Through good dispersion, the processing aid improves the surface quality without affecting organoleptic properties.
By insuring good fusion and the homogenisation of other additives, the addition of PARALOID processing aids will optimise the physical properties of the finished product.
The addition of a PARALOID processing aid improves manufacturing production and gives a finished product the high gloss and excellent surface quality required.
Melt fracture, which is related to the compound formulation and to the shear stress, shear rate, and temperature of processing, limits manufacturing production rates and can reduce the quality of the finished product.
The photographs below show how PARALOID K120ND reduces the melt fracture of extruded rods, greatly improving the surface quality.
Because PARALOID processing aids are fully compatible with PVC, they do not affect the optical properties. In critical applications, K120ND is generally chosen for its superior performance.
Transparency was measured using a Hunterlab colorimeter, with 1-litre 34g. round-ribbed bottles.
PARALOID K120N and K120ND processing aids help dispersion of compounding additives, and do not contribute to gel formation. For critical applications, K120ND has an especially good rating.
Inflated Parison Test (Sn-Stabilised)
Test rating 0-12 where
PARALOID K120N and K120ND processing aids used in Ca/Zn-stabilised formulations for food products, such as water bottles, have a negligible effect on taste. In the following test, bottles made with a formulation including the PARALOID processing aids are filled with mineral water, which is then compared to the same mineral water in glass bottles.
The addition of PARALOID K120N processing aid gives better control of wall thickness in extruded profile and pipe. This better control increases efficiency and output, and thereby reduces production costs.
The results in the following tables were obtained from one-month extended trials producing large pipes of various diameters and wall thicknesses.
Wall Thickness Variations
Wall Thickness and Output Variations
Standards and Formulations
Test Standards and Descriptions
Inflated Parison Test
In this test, the parison is extruded vertically from the Bekum die to the floor. The hot parison is then squeezed between two vertical plates and allowed to cool. The cold parison is removed from between the plates and cut carefully into 10-cm segments. Each segment is weighed and plotted against the parison length. The segment weights are plotted back to the zero length, to give the weight/cm of the first part of the parison exiting the Bekum die.
The die swell is calculated as the ratio of the zero-length weight of the parison with processing aid to the zero-length weight of the parison without processing aid.
The Rheotens Extensiometer is an instrument designed to measure elongation and stress of polymer melts. The Rheotens Extensiometer is comprised of an extrusion gear assembly, a programmer, and a chart recorder.
The programmer is used to control the speed and acceleration of two cogged wheels in the extrusion gear assembly. The polymer melt strand is passed between the two cogged wheels, and the chart recorder records the force and velocity.
The operator first sets the speed and acceleration, typically to the same linear speed as the extrudate, and then places the polymer melt strand between the two cogged wheels. The speed is then increased, and the resulting elongation and stress can be charted.
Dow makes no warranties, either expressed or implied, as to the accuracy or appropriateness of this data and expressly excludes any liability upon Dow arising out of its use. We recommend that the prospective users determine for themselves the suitability of Dow’ materials and suggestions for any use prior to their adoption.
Suggestions for uses of our products or the inclusion of descriptive material from patents and the citation of specific patents in this publication should not be understood as recommending the use of our products in violation of any patent or as permission or license to use any patents of Dow. Material Safety Data Sheets outlining the hazards and handling methods for our products are available on request.
PARALOID is a registered trademark of Dow/Philadelphia (USA).
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