Fluoroplastic blends and laminates for low emission fuel hoses
Publication Date: 2007-Apr-06
The IP.com Prior Art Database
THV/FEP blends and laminates for low emission fuel hoses.
THV/FEP blends and laminates for low emission fuel hoses
In the automotive fuel hose market there is a need to develop a new lower permeation fuel barrier to meet increased global customer demands for lower or zero emissions. Increased use of alcohol based fuels such as CE10 also demand better permeation resistance. One approach has been to use Dyneon™ THV laminated to NBR (Fig. 1). While bonding performance with THV and NBR is satisfactory, the permeation resistance needs to be improved to meet newer more stringent emission regulations. FEP has excellent permeation resistance to automotive fuel, but negligible bondability to other fuel hose materials without an etching step. Etching steps are often unacceptable.
A unique approach is to use a blend of THV and FEP to improve permeation resistance and yet maintain acceptable bondability to other polymers such as ECO, HNBR, NBR and FKM. Dyneon™ THV 815/FEP 6307 blends give great permeation resistance to CE10, almost as low as FEP (Fig. 2).
Fig. 1 Hose Construction
Permeation constant (g·mm/m
THV 500 THV 815 FEP 6307/ THV 815 (70/30)
FEP 6307/ THV 815 (80/20)
Fig. 2. Permeation Constants CE10 at 60oC
The following examples will demonstrate and explain improved adhesion between FEP/ THV blend and NBR by adding DBU or FX 5166 to the NBR compound.
In Examples 1 to 5, NBR compounds in Table 1 were prepared using a two roll mill by compounding NBR rubber (34% acrylonitrile content, available as Krynac 34E60 from Lanxess, Pittsburgh, PA) with 60 parts of a carbon black (N762, available from Cabot, ), 5 parts of calcium hydroxide (available as Ca(OH)2 HP from C. P. Hall, Chicago, IL), 5 parts of calcium oxide (available as CaO from C. P. Hall, Chicago, IL), 5 parts of DOP (dioctyl phthalate, available from Aldrich Chemical, Milwaukee, WI), 3.5 parts of dicumyl peroxide (available as Di-cup KE from Hercules), 2 parts of stearic acid (available from Aldrich Chemical, Milwaukee, WI), and adhesion promoter DBU (1,8-diazabicyclo[5.4.0]undec-7-ene, available from Aldrich Chemical, Milwaukee, WI) or FX 5166 (available from Dyneon LLC, Oakdale, MN). Also the blends of 70 wt% FEP (available as FEP 6307 from Dyneon LLC, Oakdale, MN) /30 wt% THV815 (available from Dyneon LLC, Oakdale, MN) and 80 wt% FEP/ 20 wt% THV 815 were prepared using a twin screw extruder.
10 cm by 10 cm sheets of compounded NBR 1 mm thick were applied onto about 200 µm thick sheets of THV 815 or FEP/ THV815 blends. Then the laminated sheet as shown in Fig. 3 was heated under pressure on a press at 160°C for 20 minutes to evaluate the adhesion between the NBR and THV 815 or FEP/ THV815 blends. A 15.2 cm by 15.2 cm shim stock with 0.75 mm thickness was used to maintain the thickness of the laminate under the heat press. The sample was removed from the press and allowed to cool to room temperature. Thre...