Two experimental HDPE blow molding grades from Dow Chemical Co.’s Basic Plastics unit in Houston are said to offer dramatic increases in ESCR, higher stiffness, and significant processing advantages over existing unimodal and bimodal resins for bottles and large parts. Introduced at the NPE show in Chicago, Dow’s Continuum EP bimodal resins reportedly exhibit ESCR nearly 15 times greater than standard unimodal HDPE and 3X to 9X greater than competitive bimodal HDPEs, including Dow’s fi rst-generation Continuum products. This ability to contain more aggressive substances could open up new applications in agricultural, household, and industrial chemicals. Larger amounts of postconsumer recycle (PCR) can also be accommodated, Dow notes.
In addition, higher stiffness for Continuum EP resins provides topload strength comparable to earlier Continuum grades and 15% to 25% greater than unimodal and competing bimodal grades. Together, these factors translate into lightweighting potential of around 10% for gallon and half-gallon bottles and about 5% for 55-gal drums.
According to Dow, previous bimodal resins have suffered from low die swell, poor pinch-off strength, and narrow processing windows relative to unimodal resins. Continuum EP bimodal grades reportedly overcome these deficits and process as well as or better than unimodals on typical wheel, shuttle, accumulator, and reciprocating-screw machines. Dow’s new resins show “drop-in” compatibility with unimodal processing conditions on these machines. This makes processing more consistent and forgiving, Dow says.
Dow will initially offer two grades of Continuum EP, both having 0.958 density and ESCR ratings of greater than 1500 hr:
•XDMDA-6630 for bottles has 0.3 MI, 27 HLMI, tensile yield strength of 3400 to 3800 psi, 2% secant fl ex modulus of 165 to 175 kpsi, and tensile impact strength of 100 to 140 ft-lb/in.2
•XMDA-6670 for drums and other large parts has 6 HLMI, tensile yield strength of 4000 to 4400 psi, fl ex modulus of 145 to 155 kpsi, and tensile impact of 230 to 290 ft-lb/in.2
(800) 441-4369 • www.dowplastics.com
Dow Chemical Company
PO Box 1206 Midland, MI 48642
Phone (989) 832-1426 Fax (989) 832-1465