Precision performance

ncluding the consumer electronics sector. Simon Lott reports.

In a neat example of using age old know-how to inspire new technology, Technical Fibre Products (TFP) started life a little over 25 years ago as an extension to the traditional paper making activities of James Cropper plc. Its nonwoven material production concept came into being when several employees at the company realised that instead of using the normal paper pulp, they could experiment with using several different types of fibre and develop a proprietary wet-laid, non-woven process for a range of applications.
TFP today offers a diverse range of products and trademarks including the Optimat range of advanced nonwovens for the composite industry and the Tecnofire range which offers intumescent passive fire protection. Other spin-offs include Supacool cryogenic tissues, high temperature insulation materials, power generation and storage, metal coated fibres and other custom products.

The machines used in the manufacturing process, of which TFP now has two manufacturing lines and a pilot line, have been developed entirely in-house and as such, the company believes that there are no other materials on the market that function in exactly the same way. In a process derived from paper making, its products today involve very short fibres (typically 6-25mm) which are essentially mixed with water, drained and combined with a suitable binder. However, one of the key advantages offered by TFP is the potential to support new and existing customers in the development of new products, ‘tailor-made’ to provide solutions using blends of different fibres and binders.

Optimum performance

After 25 years of development, TFP claims an extensive material knowledge and works with glass, ceramic, aramid, polyester, carbon and metal-coated fibres, which in addition to being tailored regarding material content, can also incorporate particulate components and use different substrates and binders for enhanced functionality. Materials can then be converted to rolls, sheets and other shapes. Depending on fibre type and project viability, final products can vary from a basis weight of 4-3,500g/m² in batch sizes from 5-500kg and a selectable forming width of 500-1,700mm.

The Optimat product range is used extensively as a surfacing veil for other composite structures in order to provide additional functionality and improve aesthetics. The main applications include surface engineering of FRP structures; wear and chemical resistance; aesthetic enhancement; controlled resistivity to heating, EMI/RFI shielding, static dissipation and for radar signature management; and supporting substrates for adhesive carriers.

Being able to engineer precise levels of electrical conductivity is another key capability and of high value to those making products that require attributes like electromagnetic interference shielding – especially crucial to the consumer electronics industry. However, the technology is relevant to more or less any product where electrical pathways need to be made. Veils can be created with an areal weight as low as 4g/m² (a key competitive advantage) and offer to the market a very lightweight, high performance, electrically conductive material which can even cater for particular shielding effectiveness across different frequency ranges. In practice, TFP’s customers will typically pre-impregnate Optimat materials and cut them to shape before they go into the final product, such as a computer or mobile phone.

Mixing it up

Product specialist Mandy Clement explains further: “We can offer a series of electrically conductive materials and because of our blending capability, we can take carbon and a dielectric like glass or aramid and produce a veil with some electrical conductivity, such as our anti-static veils. These are useful for products such as composite tanks or pipes where they provide excellent chemical resistance, but not being 100% carbon means we can keep costs down. If necessary we can move from this glass/carbon mix all the way up to 100% carbon and can change the grammage to increase performance with a certain weight penalty.

The company claims that all materials boast an exceptionally even fibre distribution and depending on the application, the orientation of fibres within the veil that is produced can be controlled. For example, if a material requires a balanced or uniform tensile strength then a random fibre distribution can be produced to achieve this. In contrast, for applications in which directionality in the material properties is necessary the fibres can be aligned up to a ratio of 30:1, highlighting the flexibility of the production process.

Clement continues: “Aramid veil for example is a very popular product for us. We sell a lot of this into the composite roll covering market. These are for industrial rollers, similar in a way to those on paper machines. They have got a surface running at very high speeds but they still need to be very smooth to produce good quality paper. The aramid veil allows it to have extremely good wear resistance.”

Expanding applications

Elsewhere in the product range and offering integrity in a no less vital way, the Tecnofire range involves a passive fire protection layer formed of an intumescent material - essentially a high temperature resistant graphite filled fibre mat - that can be taken and infused with resin. In one particular example it has been infused as part of the structural composite component of a bus. In the event of fire the material will expand to give a stabilised char.

The idea is that the char – because of its construction – will help to insulate and protect the underlying structure and allow the customer to complete the various fire test standards necessary for their particular industry and country. A range of intumescent mats have been developed which vary in thickness from 0.5-6 mm and deliver a variety of performance attributes. In line with the customer focus and as the materials are never used in isolation, the Tecnofire material is always tailored and tested within the complete material construction for the application.

Supplementing the UK facilities at Burneside and Crewe, TFP also operates from the USA through a holding company, Tech Fibers Inc, which amongst other things provides a fibre metal-coating capability. Nickel coated carbon and copper-nickel coated carbon fibre remain key products owing to them being relatively inert yet offering good electrical properties. The capability to work with other metals is also available. In this process, carbon fibre goes through an electroless chemical deposition or electrochemical deposition method. To produce a continuous coating, the tow is run through a bath of chemicals to ensure the most even layer possible. “By making these ourselves” explains Clement, “we have the ability to make these coatings to a very precise thickness, which is an important part of the enhanced functionality for electrical conductivity and high performance that characterise these products.”

Focused on technology

The company describes that the last year has seen records broken for revenue and operating profit. The commercialisation of new materials and appetite for new products has put the company back on track to meet its longer-term aspirations, with demand in the second half roughly equivalent to pre-recession levels. In fact the figures show that it has jumped from just under £10 million turnover to over £13 million during 2010/2011.

Despite this, TFP is keen not to lose its focus as a supplier of specific, highly engineered, high value products, and has no intention of becoming a mass producer of commodity materials.
“Within our niche capability any market that approaches us will get a response,” continues Clement. “We have longer-term research projects in certain areas such as in fuel cells and electromagnetic interference. In particular we’re working with Johnson Matthey developing gas diffusion layers for fuel cells and are also involved in projects for thermoplastic composites. In addition to these innovations for the future, our Technology Team’s primary focus is working on customer projects with shorter-term goals, delivering new products tailored to meet customer requirements over shorter timescales. We choose our partners carefully and there needs to be good synergies.

“Because of the diversity of our customer base, ranging from blue chips to tiny start-ups, each project has its own strategic goals regarding where we position ourselves. Usually when people come to us, the most important aspect is about finding performance. To achieve this performance can involve working with both customers and their supply chain partners in order to build an understanding of the material requirements and enable usto design an optimised solution.

“We have various arrangements with customers. They might simply be machine time arrangements or more commonly partnership type arrangements, and usually we’d go through a specific product development process. New products are coming through continuously. Some customers will have exclusive products that we will not sell those to anyone else, while some have a more general product that we can offer as part of our range.”

A recent example of this specialisation is ia range of microfine polyester veils, which have a thickness of as little as 40µm. These materials are used in applications such as supporting carriers for adhesive films, where the veil provides an integral support to the film to allow handling. Another key project currently up and running involves working with recycled carbon fibre. The result is that TFP can now produce highly aligned carbon fibre veils from recycled unidirectional prepreg.

As it looks to the future, it is clear that the potential for the use of these nonwoven materials is far from fully realised, and that those offered by TFP provide an important alternative to more conventional materials where precise performance goals are being sought.

Technical Fibre Products will be exhibiting at JEC Europe on stand K52.

www.techfibres.com