ENDEX CHEMICAL FOAMING AGENTS, BLOWING AGENTS, NUCLEATING AGENTS, PROPELLING AGENTS

These enhanced performance products are leaders in these technologies, providing the OEM and processor with flexibility in design and processing. Strong technical support fully complements the quality and versatility of our products, and our commitment to the customer is evident in everything we do.

Multi-Process Application

Endex chemical foaming agents are intended for use in a wide variety of processes, including:

Injection molding for cycle time reduction, sink marks, warp reduction, shrink control.
Structural Foam Molding (SFM).
Gas Counter-Pressure foam molding.
Nitrogen SFM for finer cell structures and extra weight reduction.
Gas Assist molding for extra weight reduction and sink elimination.
Extrusion of Sheet, Film, and Profiles.
Blow Molding of foamed parts.
Rotational Molding of foamed parts.

Endex produces very fine, closed cell structures and smooth surfaces, combining endothermic properties, quality and efficiency, with versatility and cost effectiveness.

Endex is available as a free-flowing powder or a high efficiency mini-pelletized concentrate, in a thermoplastic resin carrier. It is designed for use in both commodity and engineering thermoplastics.

Endex Product Listing

Endex ABC 2750
General purpose endothermic CFA master batch, for use in a wide range of thermoplastics, in injection molding or extrusion.

Endex NBC 2750
Endothermic CFA master batch. Used with nitrogen gas in low pressure structural foam molding of large parts-pallets, boxes etc.

Endex 1010
Endothermic high temperature CFA master batch, for use in PA, PC, PET and other moisture-sensitive thermoplastics.

Endex 1040
Exothermic master batch CFA, with high gas yield and no color shift in thermoplastic parts.

Endex 1041
General purpose exothermic master batch CFA.

Endex 1042
Endo-Exothermic hybrid master batch CFA, for injection molding and extrusion.

Endex 1750
Endothermic master batch CFA combining performance and cost effectiveness.

Endex 2650
Endothermic CFA master batch gives very fine cell structures in extrusion or injection molding.

Endex 3750
Endothermic CFA master batch, for use in thermoplastics containing fillers such as calcium carbonate.

Endex 9900
Free flowing dustless powder for use in extrusion or molding of PVC and low temperature polymers.

Endex ABC 100
General purpose endothermic powder grade for use in extrusion and injection molding.

The above is a partial list of available products.
For specific application or advice, please call 630-629-6600 and ask for Technical Support.

MOLDING GUIDE

This Molding Guide applies to the use of Endex Chemical Foaming Agents in terms of Injection Molding and Structural Foam Molding.

INJECTION MOLDING

Sink Marks and Warp: Use Endex products to remove sink marks and reduce warping. Inject a short-shot (about 10% short) with minimum holding pressure and cushion, and gradually increase the shot size until the mold is full. This allows the gas in the melt to complete the filling of the mold, with minimum pressure on the melt. With the proper level of Endex, and adjustment of the shot size, the part will have no surface effects or splay, and the injection stresses will be minimal.

Cycle Time: The internal gas pressure improves contact with the mold cooking surfaces, while the endothermic properties of Endex contribute to the cooling of the part, and this can reduce cycle time.

Temperature and Clamp: Use of Endex may also allow a reduction in processing temperatures, and a reduction in the mold clamping force.

Use of Polymer Regrind: The decomposition products of Endex do not affect the use of regrind, since there is no residual activity in the regrind.

STRUCTURAL FOAM MOLDING

Use Level: Use levels will vary with the application, but a 1% level for Endex ABC 2750 & Endex 2650 is a good starting point. The use level can then be optimized for maximum efficiency and cost effectiveness.

Venting of the Mold: In SFM, venting is usually in the range of 0.005-0.010 inches to permit fast air escape, and thus avoid compressing the foam structure. Temporary vents can be made using adhesive-backed aluminum or lead tape (available in 0.0 05, 0.010 inch thickness from 3M)

Shot Size: Start with a shot about 25% less than the mold capacity, and adjust to fill the mold over several shots.

Holding Pressure and Cushion: Since it is the gas pressure in the melt which fills the mold, the use of holding pressure will prevent the mold from filling properly. Do not use holding pressure, and ensure that the screw bottoms out (I.e. do not use a cushion during injection).

Injection Pressure and Speed: Set the injection pressure high enough to achieve the maximum available injection speed. High speed injection usually gives the best surface quality, but some resins are sensitive to the high shear generated during fast injection and the speed may have to be adjusted to suit these materials.

Back Pressure and Screw Speed: The use of back pressure (usually 100-200 psi) improves mixing and consistency in the polymer melt. Screw speed is normally 20-50 RPM.

Temperature Profile: should be set to achieve a suitable melt temperature for the polymer, however the rear zone/hopper temperature should not be so high as to cause premature decomposition of Endex, and thus loss of gas back through the hopper. A temperature range of 380 - 420°F (193 - 215°C) at the rear zone/hopper is suitable for most polymers.

Mold Temperatures: Surface finish, skin thickness and cycle time are all affected by the mold temperatures. Hot molds usually produce thinner skins, smoother surfaces and longer cycle times than cool molds. The normal range is 60 -140°F (16 - 60°C), and the polymer manufacturer’s recommendations are usually appropriate.

Use of Polymer Regrind: The decomposition products of Endex do not affect the use of regrind, since there is no residual activity in the regrind.

EXTRUSION GUIDE

This Extrusion Guide applies to the use of Endex Chemical Foaming Agents in a variety of processes including:

Sheet	Pipe/Tubing
Profiles	Blow-Molding
Tape	Monofilament
Film	Wire Coating

Extruded thermoplastics can be foamed to 50% or more, of their original densities. Successful extrusion depends upon adjusting temperature & pressure profiles of the extruder to use Endex most efficiently. Pressure must be maintained on the melt to prevent foaming in the extruder. This can be done by using a high compression screw, fine screen packs, or temperature reduction in the front extruder zones to produce back pressure. Pressure can also be controlled by adjusting screw speed. The die temperature is normally lower than for solid extrusions to enhance surface appearance.

Use Level: Endex use levels will vary with the application, but 0.5% level is a good starting point. The use level can then be optimized for maximum efficiency and cost effectiveness.

Dies: Use a die with minimum land-length ratio, preferably no larger than 10:1, to ensure high pressure on the extrudate, thus preventing premature cell formation. If the pressure drops too low within the die land, cells can form while there is still shear stress on the melt, causing irregular cell formation and poor surface appearance.

Screws: A conventional single-stage, unvented screw is normally used. To ensure adequate mixing of polymer and Endex the Length:Diameter (L/D) ratio of the screw should be at least 16:1. If the screw has a vent it should be sealed; if this is not possible then zone temperatures prior to the vent must be kept below the decomposition temperature of Endex (less then 300°F, 149°C),
which may not be practical on short L/D screws.

Temperature Profile: The temperature profile should be set to achieve a suitable melt temperature for the polymer, however the rear zone/hopper temperature should not be so high as to cause premature decomposition of Endex, and thus loss of gas back through the hopper. A temperature of 360° F (193° C) at the rear zone/hopper is suitable for most polymers.

Take-off Equipment: It is essential to use take-off equipment capable of achieving the desired quality of extrudate. Normal take-off equipment may be used, with extra cooling being advantageous. The distance from the die lip to the take-off equipment is critical to maximum expansion consistent with the desired surface appearance.

Foamed sheets should be passed through chill rolls to polish the surface and set the dimensional stability, and the roll spacing should be adjusted to avoid over-compression of the sheet. Draw down and vacuum sizing (if used) should be regulated for consistent foam.

Use of Polymer Regrind: The decomposition products of Endex do not affect the use of regrind, since there is no residual activity in the regrind.