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New DuPont technology bonds dissimilar plastics
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Du Pont Engineering Polymers
: 20 October, 2004 (Company News) |
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DuPont has developed a new structural bonding technology which creates strong bonds between almost any dissimilar plastics. |
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It can be applied in conjunction with most processes in which the two surfaces to be bonded are brought together in the molten state, such as two-component moulding, over-moulding or certain types of welding.
The anchoring mechanism is in the form of a micro-porous tie-layer, which creates a strong physical bond between two materials even when they have no chemical compatibility. In the past, it was difficult to get good bonding between two plastics which are not chemically similar. The choice of the materials was limited and the strength of the joint was often poor, leading to delamination or other problems.
The resins to be bonded with the new DuPont technology need no surface treatment in a pre-moulding or post-moulding operation; there is no need to use speciality grades containing compatibiliser, which generally reduces resin properties and increases its price. Standard moulding, welding or extrusion equipment can be used with DuPont’s structural bonding technology. Additional equipment (e.g. robots) is necessary only for cutting and positioning the tie layer in the cavity, depending on the application.
Bonding dissimilar plastics is generally needed when different functionalities are required from the two materials. For example, a hard-soft combination of a rigid, structural material and a rubbery material may be wanted to create a sealing effect, to produce a high-friction surface, for sound or vibration damping, or for comfort (soft touch). The tie-layer adds between 0.1 and 0.3 mm in thickness to the complete part after processing.
DuPont has made patent applications to cover this discovery.
Early application developments include soft-touch components made by over-moulding or two-component moulding. |
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