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DuPont™ Keldax sound barrier resins deliver practical ... · PDF fileDuPont™ Keldax® sound barrier resins deliver practical, affordable noise ... automotive production line. Door

Mar 18, 2018




  • DuPont Keldax sound barrier resinsdeliver practical, affordable noise reduction

    Easy to shape, easy to work with, easy to install.

    Components made with DuPont Keldax help today's manufacturers reduce objectionable noise and

    increase consumer-perceived quality.

  • DuPont Keldax resins are filled ethylene polymers designed to provide economical, non-halogen sound barriers in automotive and industrial applications. In automotive passenger compartments, Keldax can help block noises emanating from interior sources, such as seat belt retractors and small motors, or from exterior sources, such as engine, transmission, suspension, tires and the road.

    EASY TO PROCESS AND FORMKeldax resins can be processed on conventional wear-resistant extrusion and injection- molding equipment. Compared with mastics and asphalt-based sound barrier materials, Keldax can be more accurately formed (heat, vacuum, and compression molded) into complex, deep-drawn shapes that exhibit excellent strength and durability. Because of their relatively high weight-to-volume ratio, Keldax resins can be applied in thin, space-saving gauges. Keldax is a recyclable thermoplastic, and can be reintroduced with virgin material as feedstock for new melt processing.

    GOOD ADHESION AND EASY ASSEMBLY Keldax resins combine excellent formability with the flexibility necessary for optimum sound barrier performance. Components made of Keldax retain their shape well, for easy installation and precise fit. When heated, Keldax adheres to a variety of substrates, including sound absorbers or decouplers, without the use of adhesives. When bonded to decouplers that have no shape-retention properties of their own, Keldax helps these decouplers hold a proper shape.

    TAILORED RESINS AND PROPERTIESKeldax resins are manufactured in accordance with ISO/TS 16949:2009 standards utilizing statistical process control techniques. The resins are supplied as pellets, available in a range of densities to suit individual applications. During manufacture, they can be further tailored to meet specific processing or end-use requirements.



    Table 1: Typical physical properties* of a medium-density grade of Keldax


    Color Dark gray

    Density 1.9 g/cc

    Tensile Strength, 23C (ASTM D638) 2.4 MPa (350 psi)

    Elongation at Break, 23C (ASTM D638) 400%

    Flexural Modulus, 23C (ASTM D790) 45 MPa (6,500 psi)

    Tear Strength (ASTM D624) 16 kN/m (90 lb/in)

    Sound Transmission Class (STC) @ 1 lb./sq.ft. (ASTM E90-97) 27 30

    *Compression-molded test specimens.Note: These data are not intended as specifications.


    THICKNESS Sound transmission loss testing has been performed in conformance with ASTM E90 using three different sheet thicknesses (surface densities) of a medium-density grade of Keldax. Measurements of transmission loss at selected frequencies indicate that acoustical performance (see chart, right) can be tailored using sheet thickness to achieve specific design requirements.











    200 400 1000 5000





    s, d


    Frequency, Hz

    50 mil 100 mil 150 mil

    0.5 lb/sq ft 1 lb/sq ft 1.5 lb/sq ft

    Keldax Sound Barrier ResinsSound Transmission Loss (ASTM E90)

  • USE OF THIN-GAUGE, DECOUPLED DESIGNS Because of its outstanding melt strength and product consistency, DuPont Keldax resins can be drawn or molded to thin gauges. This allows engineers to control resin placement and minimize the total weight of a sound control component.

    Thin gauges are particularly useful in double-walled barrier systems, which include an air space or decoupler material to isolate sound barrier walls from each other. As shown below, the transmission loss of a decoupled system can exceed the sum of the transmission loss of the individual walls.

    DOUBLE-WALLED (DECOUPLED) TRANSMISSION LOSSA double-walled sound barrier system, such as an auto carpet backed with Keldax, along with the underlying absorber pad and sheet metal, can exceed the sum of the transmission loss of the individual walls. As illustrated (left), the slope for the sheet metal, and for the sheet metal with applied mastic, is approximately 6 dB for a doubling of the frequency (per octave). The double-walled barrier system using Keldax has a slope of approximately 18 dB per octave.

    By adjusting the amount of Keldax used, the acoustical performance of a sound barrier system can be easily optimized to meet the requirements of the particular vehicle or application.

    (Schematic courtesy of Application of Noise Control and Heat Insulation Materials in the Automotive Industry, May 10-13, 1993, Traverse City, MI, prepared by SAE Sound & Heat Insulation Committee,

    compiled by T. Hirabayashi, D. McCaa, R. Rebandt, P. Rusch and P. Saha)

    WHERE KELDAX CAN WORK FOR YOUKeldax offers proven performance in automotive and other industries where a close-fitting, economical sound barrier isneeded.

    AUTOMOTIVE APPLICATIONSWidely used as automotive carpet backing, Keldax also can be highly effective for other vehicle sound barrier applications including:

    Dash insulators Carpet under-layers and mats Wheel well covers Rear seat barriers and package trays Trunk liners Door panel water shields Seat belt retractors Small motor housings Wherever a formed sound barrier is needed

    INDUSTRIAL AND CONSTRUCTION APPLICATIONSDuPont Keldax resins can be used with a variety of flexible and rigid substrates to deliver cost-effective, nonhalogenatedsound barrier layers in industrial and construction applications. Examples include noise control blankets surrounding heavyconstruction zones and a variety of other building and industrial enclosure components and interlayers.



  • In an automotive dashboard assembly, Keldax resins can be molded to conform

    exactly to the complex contours and deepdraw styling found in today's vehicles.

    One-piece, form-fitting carpet units backed with Keldax resins retain their shape while being flexible and easy to

    handle on the automotive production line.

    Door panel water shields of Keldax provide the high density necessary to reduce noise,

    vibration and water leakage while minimizing part thickness.


    AmericasDuPont Company, CRP730/4225-8974 Centre RoadWilmington, DE 19805 U.S.A.Telephone +1 302 996 7911Toll-free 800 438 7225

    DuPont do Brasil, S.A.Alameda Itapecuru, 50606454-080 Barueri, SP BrasilTelephone +55 11 4166 8000Toll-free 0800 17 1715Fax +55 11 4166 8736

    Asia PacificDuPont China Holding Co., Ltd.Bldg. 11, 399 Keyuan RoadZhangjiang Hi-Tech ParkPudong New DistrictShanghai 201203, ChinaTelephone +86 21 3862 2888Fax +86-21-3862 2889

    Europe / Middle East / AfricaDuPont de Nemours Intl. S.A.2, Chemin du Pavillon PO Box 50CH-1218 Le Grand SaconnexGeneva, SwitzerlandTelephone +41 22 717 51 11Fax +41 22 717 55 00

    The technical data contained herein are guides to the use of DuPont resins. The advice contained herein is based upon tests and information believed to be reliable, but users should not rely upon it absolutely for specific applications because performance properties will vary with processing conditions. It is given and accepted at users risk and confirmation of its validity and suitability in particular cases should be obtained independently. The DuPont Company makes no guarantees of results and assumes no obligation or liability in connection with its advice. This publication is not to be taken as a license to operate under, or recommendation to infringe, any patents.

    Copyright 2014 DuPont. All rights reserved. The DuPont Oval Logo, DuPont, and Keldax are registered trademarks or trademarks of E. I. du Pont de Nemours and Company or its affiliates. Doc. Reference No. K27594


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