20, 1998 Design News
Materials Editor Gary
Chamberlain cites noteworthy elastomer products
Extra-soft TPE 'grips' competition
When it comes to a thermoplastic elastomer (TPE) compound,
softer often means better when it comes to touch. But
does it still retain the "grippy" feeling
required in many applications? If that product is DYNAFLEXr
G-6725 grade from GLS Corp., the answer is "yes!"
Made with Shell Chemical's KRATONr G polymer, the TPE
is for insert molding, over molding, or two-shot molding
onto harder DYNAFLEX grades. Typical physical properties
of the 100% recyclable compound include a 25 Shore A
hardness and a specific gravity of 0.089. Price: $2.45
to $2.98 per lb, depending upon quantity.
Elastomer becomes a lifesaver
Just how buoyant can a material be? In the case of
a "new generation" of continuous cured and
modified rubber compounds from Sentinel Products Corp.,
"they can outperform existing PVC/vinyl nitrile
materials at a competitive price," according to
Scott Smith, COO. The new elastomeric metallocene-based
compounds, EMRTM 220FL, recently received
UL recognition for personal flotation devices. They
have a buoyancy rating of 60, provide softness properties
similar to PVC/vinyl nitrile materials, and can be easily
thermoformed into 3D parts. The compounds remain flexible
at low temperatures, resist fungal and bacterial growth,
and have high UV and chemical resistance.
High-melt TPU forms multi-layer laminates
If you have ever experienced a tacky mess when trying
to bond laminates under high temperatures, Stevens Urethane
has a solution with its new "super-high-melt"
polyether thermoplastic polyurethane (TPU). Stevens
ST-1665 is said to provide one of the highest melt temperatures
available in a thin urethane film, between 190 and 210C.
Because it requires a higher than usual temperature
to become tacky and bond with other materials, its strength
and barrier characteristics are not affected by processing
temperatures that might melt "normal" urethane
films. In multi-layer laminations, the material is typically
used on the "high-heat" side of the lamination.
The high-melt urethane maintains its integrity and performance
properties, while films on the other side of the substrate
soften and bond, forming a multi-layer lamination.
TPU with more bounce per ounce
Can a hard ester and a high-rebound thermoplastic reside
in the same family? They can when they are part of the
new Estaner thermoplastic polyurethane product portfolio
from BF Goodrich Specialty Plastics. The Hard Ester
line includes extrudable materials that provide chemical
resistance and a high-heat profile for dynamic, high-abuse
applications, such as hose and tubing. The portfolio,
which covers a range of hardnesses, is said to be more
cost-effective than nylon. The High-Rebound TPUs offer
"the first products in an innovative portfolio"
for a variety of applications and industries. The materials
exhibit improved tensile strength, strong tear and abrasion
resistance, consistent properties, lot-to-lot scrap
reprocessing, and recyclability of finished parts.
Materials 'air out' BMW air duct
Combine a hard polypropylene core and a soft, elastic
sealing component and what do you get? For BMW, the
material duo significantly cut costs for air duct systems
versus previous ducts made of thermoset rubber, copolyester,
and polypropylene. The BMW system requires high-temperature
resistance and elasticity, as well as long-term properties
to ward off chemicals and aging for under-the-hood operation.
Using 3D/sequential blow molding, Santoprene thermoplastic
rubber from Advanced Elastomer Systems (AES) is molded
with a hard polypropylene/glass-fiber material. True
to its name, 3D/sequential blow molding enables the
production of parts in three dimensions, while allowing
molders to change from one material to another during
the production of one part. "This application has
excellent potential for automotive OEMs around the globe,"
says Juergen Gloeckler, AES' automotive director, Europe.
Medical TPVs don't need drying
No longer will you need to pre-dry thermoplastic vulcanizate
(TVP) elastomers used to produce medical devices or
healthcare products--providing you turn to a new series
of TPVs from Teknor Apex's Plastics Div. The Uniprener
7010 Series compounds are nearly identical to advanced
Uniprene materials recently introduced for general industrial
applications. However, they have been reformulated with
ingredients that conform to 21 CFR for medical and food-contact
uses. Not only do the TPVs reduce or eliminate pre-drying
because they absorb less moisture, but they cost less
to color, since they exhibit less yellowness in natural
(uncolored) form. Currently under evaluation are overmolded
plugs in surgical cables and plunger tips for syringes.
Soft-touch adds sales appeal
Add a soft-touch to your products and you could add
to your sales. That's what Warner Tools did when it
introduced the ProGripTM Series, an expanded
line of paint scrapers and putty knives that feature
soft-touch handles. Warner designers selected polypropylene
for the hard handle substrate, then added SARLINKr 3460,
a high-flow TPE from DSM Thermoplastic Elastomers, for
the soft component, "because of its processing
abilities, strong chemical resistance, and cosmetic
appeal," says Warner Product Development Manager
David Henke. A two-shot insert loading injection molding
process was used to make the grip. Its popularity with
decorative and maintenance pros proved so successful
that Warner has decided to upscale its entire line of
products using the SARLINK material.