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Process for engineering polymer coatings

Objective


1. Thermoplastic polymers have been developed for the new thermal spraying process. The polymers are based on PE, EAA, UHMWPE and thermoplastic epoxies. Evaluation by the end-user partners has shown that the polymers provide improved splat flow and high strength in the coating state.

2. Co-extrusion of two appropriate polymers to produce a two-phase material has been shown to provide improved performance. The two-phase polymers are derived from a high-viscosity polymer and a low-viscosity polymer. The improved performance is in the terms of:
a) grindability with respect to particle size distribution and increased throughput;
b) coating quality (mechanical strength, wear and corrosion resistance) due to improved particle flow during deposition.

3. A thermal spray system has been designed for the deposition of non-degraded thermoplastic coatings. The equipment uses a combustion reaction to generate gas flows of controlled temperature and velocity profiles. The feedstock powder particles are maintained in a thermo-kinetic window during deposition: the temperature is between the melting and degradation temperatures, and the particle velocity at impact is sufficient to achieve adequate flow.
Objectives and content
The proposal is directed at developing a new
environmentally compatible, surface-treatment technology
for increasing the efficiency of operation and durability
of engineering components and outside steel structures.
High-performance polymer coatings have major potential in
raising the lifetime of industrial products and added
value of industrial products, particularly for heavy-duty
applications. However, these polymers cannot be
adequately applied by the existing coating techniques.
Painting incurs environmental problems and produces
coatings of only limited quality. Powder coating
techniques require oven treatments so that they cannot be
used for large outside structures on-site, and the
coatings also have limitations in quality. Flame
spraying inevitably results in some degradation of the
temperature-sensitive polymers in the hot flame, which
adversely affects coating quality and may produce
hazardous fumes.
The proposal will develop a new low-temperature, highvelocity thermal spraying process for applying highperformance polymer coatings for heavy-duty applications
requiring corrosion, wear and impact resistance. The
equipment will be portable and operable by hand or
robotically on individual components in-house or on
outside assembled structures on-site. It is a singlestage one-shot technique and its dry method of
application will avoid environmental difficulties. A
further advantage of the proposed process is that it will
enable the recently developed high-performance polymers
to be processed to coatings. High-performance
thermoplastics, such as ultra-high molecular weight
polyethylene and advanced copolyolefins, have remarkable
mechanical and chemical properties in the bulk state.
However, these polymers cannot be produced adequately as
coatings by the existing powder coating techniques
because of their high viscosities, which restrict the
flow necessary for the formation of dense deposits.
The proposed process will avoid degradation and deposit
high-performance polymer coatings. This will be achieved
by processing the polymer within a thermal window defined
by a lower limit for adequate particle flow and higher
limit for the onset of thermal degradation. The lower
limit is substantially reduced and the thermal window
widened by the use of high gas velocities, which will
induce extensive particle flow even in high-viscosity,
high-performance polymers. In addition, the feedstock
polymers will be especially synthesised for
processability and coating performance. The low surface
energy of many polymers, which adversely affects the
adhesion, will be overcome by the introduction of
functional oxygen derivatives. The proposed technique
will also enable the production of polymer-matrix
composite coatings for enhanced corrosion, marine
fouling, and wear-resistance. Once the synthesis of a
new family of tailor-made polymers, the development of a
new cryogenic grinding technique and new spraying process
has been completed, the project will be directed at the
optimisation of the coating quality. User companies in
offshore oil/gas installation, automotive and railway
rolling stock industries will evaluate tailor-made
coatings with the aim of achieving quantified
improvements over conventional materials. The Consortium
will assess the industrial potential of the process and
products in the manufacturing and construction industries
in general.
The proposed process is inexpensive (5-lOkECU) and
amenable for use by SMEs. It is an environmentally
compatible technology involving no emissions/sludges, the
reclamation/repair of used components and the recycling
of waste bulk polymers. The proposal conforms to
Workprogramme areas 2.1.3M, 1.2.2M, 2.4.1 M, 2.3.4M and
2.1 .3L.
BE97-5147

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

DOW DEUTSCHLAND GMBH & CO. OHG
Address
1,Industriestrasse 1
77836 Rheinmuenster
Germany

Participants (5)

Akzo Nobel Coatings S.p.A.
Italy
Address
Localita Villanuova
25029 Verolavecchia
Costamasnaga SpA
Italy
Address
Viale Iv Novembre 2
22041 Costamasnaga
Ramboll Hannemann & Hojlund A/S
Denmark
Address
125A,frodesgade
6700 Esbjerg
South Bank University
United Kingdom
Address
103,Borough Road 103
SE1 0AA London
Speedline SpA
Italy
Address
Via Noalese 152
30030 Caltana Venezia