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NCF Resinply continuous moulding combining carbon NCF and thermoplastic resin film

News International-French

7 Jan 2020

Shindo succeeded in continuous forming C-channel shapes using their NCF Resinply product Shimteq NCF D200CR.

NCF Resinply continuous moulding combining carbon NCF and thermoplastic resin film
Thermoplastic composite materials are easy to manage because they do not involve chemical reactions during moulding and have high toughness due to the molecular structure in which the polymer is entangled. Furthermore, they are highly recyclable because they can be melted and solidified several times.

Shimteq NCF D200CR is a carbon non-crimp fabric (NCF) with a three-layer structure in which carbon fibres aligned at 45° in two directions and a PA6 film of thermoplastic resin as a matrix are layered and stitched with polyester fibres. This moulding process uses a material with a laminated structure of [+45/PA6 film/-45] 5s, which is a stack of 10 sheets of Shimteq NCF D200CR.

The structure undergoes a preheating process, and the upper and side surfaces are pressed into a C-channel shape. The shape is 59mm wide, 50mm high, 2mm thick and 3mm in radius. In this pressurization process, the company succeeded in forming the shape continuously by repeating the pressurization and depressurization steps while feeding the material in the longitudinal direction.

Cross section of moulded C-channel shape
This shaped product can be moulded continuously at 130mm/min or higher, and no repeated heating and pressurization are required in the subsequent process.

Under certain conditions, some of the resin-impregnated part and the transfer of the mould shape derived from moulding can be seen but, there is no change of fibre orientation that is a problem in pultrusion moulding. This occurs, in particular, when the reinforcing fibres are oriented in the bias direction, that is + 45° or -45° with respect to the longitudinal direction, and there are no carbon fibres oriented in the longitudinal direction of the moulded product. In such a laminated orientation, it is extremely difficult to maintain the fibre orientation in pultrusion moulding, but this can be achieved by optimizing the moulding technology.

Furthermore, the matrix of Shimteq NCF D200CR is a PA6 thermoplastic resin, and it is difficult to draw thermoplastic composites except in special cases where monomers and oligomers are used to reduce viscosity, and then need to be cured for polymerization as an additional process. Since on-site polymerization involves chemical reactions, temperature control during curing process is very important, and temperature and humidity control of highly reactive monomers and oligomers is also required for material storage. Shimteq NCF D200CR uses an already-polymerized PA6 film, so this quality control is not necessary.

NCF Resinply continuous moulding combining carbon NCF and thermoplastic resin film
Shimteq NCF D200CR has a special form in which carbon fibre as a reinforcing fibre and PA6 film as a matrix are integrated by stitching. Therefore, unlike general thermoplastic prepregs, it offers a high drapeability at room temperature, and thus high shape following, and because the carbon fibre is in NCF form, fibre linearity can be maintained during moulding and the moulded parts demonstrate high mechanical and physical properties as a composite.

The continuous moulding technology used allows continuous moulding of various cross-sectional shaped products by optimizing process parameters such as top and side pressure, pressing time, heating temperature, and preheating temperature. Shindo will continue to work on further developments in a wide range of applications such as aircraft, automobiles, railways, architecture, and ships.

More information about Shindo's NCF Resinply in JEC Composites Magazine issue #132, p.22.

JCM 132 Shindo