Reactive vegetable oils for treating timber – exploring the potentialDennis JonesTimber, Centre for Materials and Engineering

Wood processing meeting presentation 26 January 2006

Overview

• Why consider new treatments?• Selection of systems• Preliminary results• Cost implications• Long term potential

Why??

• Research and industry continually looking for new options– BPD– Environmental aspects

• Range of new systems– Organic biocides– Heat treatment– Acetylation– Other chemical treatments– Oil treatments

• Need to demonstrate potential

Selection of systems

• Basic oil treatment known for some time– Royale process– Menz-Holz

• What about improved systems– Chemistry of the oil– Additives

• Two recent projects– Partners in Innovation (PiI)– EU Fifth framework (CRAFT)

• Modified linseed oil

The concept

• Treatment in high temperature oil– Above 100oC

• Two different methods of treatment– Thermal– Chemical

• Can we work with green / wet wood?– Reduce drying costs

The process

Impregnation vacuumpressure techniques

wood

Removal of residual water at > 100 °C

curing oil

reactive oil

Reaction of reactive oilwith wood at approx.

200 °C

Removal oil from the surface

and oxidative polymerisation

“Treated” wood

water

Three processing methods

• Reactive oil (UZA) impregnation, UZA heating medium• UZA impregnation, linseed oil heating medium• UZA impregnation, rapeseed oil heating medium

• Compare to:– Linseed oil impregnation and heating– Rapeseed oil impregnation and heating

Treatments carried out

• Laboratory scale • Pilot plant scale

Results - biological testing

EN113 Coniophoraputeana

EN113 Poriaplacenta

ENV807 Soil bed test

EN252 Field test

Very durable / durable

30 - 60 year service life (HC3)

Very durable / durable

15 - 30 year service life (HC4)

Durable

15 year service life (HC4)

Results - Mechanical properties

• In line with otherthermal treatments

-18 -16 -14 -12 -10 -8 -6 -4 -2 0 2

MOR

MOE

Impact

Visual assessment

• Lab scale preparation– Very good appearance– Easy to control

• Pilot scale preparation– Occasional poor appearance– Difficult to control surface curing– Contamination of oil

Cost assessment

• Need to consider cost of pilot plant – Convert preservation plant– Heating requirements of reaction vessel and oil storage tanks– Extra tanks and drainage requirements if considering two oil systems

• Cost of oil– Estimate £1 per litre reactive oil, 30p / L linseed or rapeseed oil– Weight uptakes typically 150 L/ m3 (as high as 600 L / m3)

• Costs typically lower end tropical hardwoods• No disposal issues

The future

• Still an experimental process• Need to find way of limiting oil build up on surface and its

curing• Does provide an excellent method of treatment, and has

been shown suitable for UK timbers, including spruce• Production costs of oil not realistic at present as only on

batch scale (greater production will lower cost)

• Further work required• Estimate of time to market 5 years