Vacuum Web Coating

Question about pumping

Dear sir

Tell me about the vacuum coating instrument. why we one backing and roughing then hivac? whats the pressure range of each process?
and
Is the Same principle used for sputtering unit or not? why?

 

 

Basics of pumping.

 

            Air is viscous. I you sweep your hand through the air you can feel the air against your hand. The are a lot of molecules that are colliding all the time with each other.  At atmospheric pressure and down to around 10^-1 mbar or 10^-2 mbar if you use some kind of impeller or piston to capture a volume of gas and remove it the remaining gas will soon rearrange itself into the available space at a slightly lower pressure.  This is all the roughing pumps are doing. Rotary vane pumps use an offset shaft to allow the rotating vane to capture a volume of gas and then seal it off from the vacuum vessel and compress the gas so that it exhausts to atmosphere an then this action is repeated for every revolution of the shaft. 

            Below 10^-1 mbar or 10^-2 mbar there is little gas left in the system and so the roughing pumps are losing efficiency and so another sort of pump is often added which is the Rootes pump or Rootes Blower. This has a pair of fast rotating lobed shafts and the principle is the same in that they capture a volume of gas and compress it but this time the compression is only enough that it feeds the roughing pump which then finishes of the job of capturing the gas, that is now at a higher pressure than the system, and exhausting it to air.  This will take the pressure down to the 10^-3 mbar or 10^-4 mbar range.  This region of 10^-1 mbar or 10^-2 mbar to 10^-3 mbar or 10^-4 mbar is known as the intermediate pressure range.  Below 10^-3 mbar or 10^-4 mbar neither the Rootes nor roughing pumps will be effective and so another type of pump is required.  The most commonly used pump is the diffusion pump particularly in aluminium evaporation metallizers. In sputter systems where there are other requirements Cryopumps or turbomolecular pumps are also commonly found.  Below10^-3 mbar or 10^-4 mbar the way the gas behaves is different. There is so little gas left in the vacuum vessel that the gas atoms undergo few collisions with other gas atoms. They will often travel from one side of the vessel to the other without hitting anything else. Thus trying to capture a volume of gas and compress it will not work well. So in this case the pumps simply rely on the statistics of the gas atoms bouncing around and finally falling into the pumping orifice. Once in the pump throat the aim is to then make sure it does not return to the system.  In the diffusion pump this is achieved by boiling oil and taking the oil vapour and jetting it downwards so that a gas atom that falls into the jet is hit by the oil vapour atoms and knocked down towards the bottom of the diffusion pump. Enough atoms are in this way collected at the bottom of the pump that the pressure is high enough that the roughing pump can be used to pump it away. The roughing pump used in this way is called a backing pump.  For turbomolecular pumps the gas atom falls into the path of a rotating fan that has angled blades that knock the atom downwards. The lack of oil in the turbomolecular pump makes this attractive where very clean processes are essential but the pumps are not as large and the costs are greater so there has to be a justifiable need for this type of pump. Cryopumps are also an oil-free pump and this simple used compressed helium to take the temperature of a surface down to temperature of 4 Kelvin where most gases will condense and freeze.  This is a collection pump and does not require a backing pump but it has a finite capacity and the ice needs to be melted and pumped away periodically. This capacity for hydrogen is limited and so for roll-to-roll coating processes where there is plenty of water vapour and a plasma that can crack the water into oxygen and hydrogen this is not a good pump as the hydrogen is one gas that does not freeze and the capacity to pump hydrogen is poor.  These pumps have the capability of pumping the system down to 10^-6 mbar or 10^-7 mbar depending on pump and system size and backing pump performance, oils used in the pumps and system leaks.

            The base pressure is often used as a measure of the pumping performance but it is also a measure of the surface area within the vessel and the leaks into the vessel. The aim in aluminium evaporation is to have a low contamination rate. Water vapour is a contaminant as it will oxidise the aluminium hence you want the metal arrival rate to be more than a couple of orders of magnitude faster than the oxygen arrival rate if you want to have a contamination rate of around 1%.  However pumping for along time to achieve a low base pressure is expensive and there is a risk of oil backstreaming which will adversely affect adhesion. So the base pressure is often an easily achieved pressure at which point the aluminium deposition process can be started and acceptable product produced. This will be different for different machines and customers.  Aluminium deposition also needs to have a low pressure so that the aluminium when evaporated does not collide with any gas but travels directly to the substrate where it condenses.

            Sputtering is a different process in that it requires a gas pressure of around 10^-3 mbar and so processing gas is introduced.  This allows more flexibility in choosing the base pressure as well as slightly different controls to balance the gas introduction and pumping to maintain a steady gas pressure in the sputtering zone.  As the sputtering zone is at a higher pressure there will be some gas scattering and so the sputtering targets are often placed closer to the deposition drum than evaporation sources are to reduce this. Magnets are used to help confine the electrons which make the ionising collisions to keep the plasma active. This combination of magnetic confinement but low pressure means that the material ejected from the target surface is not scattered much and so most of it will reach the substrate where it is condensed to form the coating.

Cooling – an often ignored process variable

            Water cooling can affect many parts of the vacuum coating process. In resistance heated aluminium evaporation the copper contacts to the boats are cooled in fact as much as one third of the power may be dissipated through these cooled contacts. If the cooling is not uniform the boats will have a skewed molten evaporation pool leading to a skewed deposition and reduction in coating uniformity. Vacuum systems, when running processes, are not a constant but are a process variable. The process will invariably heat up the chamber over time changing the rate of outgassing from the surface and so changing the level of contaminant gas in the process.  Cooling is often done using site water that is used and sent to the site drain. This can mean that the temperature of the water is different depending on the season which in turn means that the process will also vary seasonally too.  Many systems do not monitor the flow or temperature of the incoming and outgoing water. If the water is interlocked it will usually be to make sure there is a minimum flow. As the site water pressure changes the flow through the system will vary accordingly and unless it falls below the minimum flow to trigger an alarm we will never be aware of these variations.  Again flow variations will lead to varying cooling capacity and system temperature differences and hence outgassing variations.  Also if the cooling water is used to cool shielding this too will vary in temperature and as these shields radiate heat to the substrate the substrate too will see differences in heat load. In a process that is running very close to the maximum heat load and could easily start to wrinkle the extra heat load from the shields could be enough tip the balance and for wrinkles to form.  In addition to all of this there is the need for the cooling to be uniform about the web centreline. If the cooing is asymmetric the web could become hotter on one edge than the other and so the thermal expansion will be more on the hotter edge than for the cooler edge. This will result in more tension being pulled on the cooler edge and this helps thermal contact to the cooled deposition drum and will exaggerate the thermal differences.  Thus it is important that the cooling of the deposition drum is uniform but also any cooled shields ought to also be similarly uniformly cooled. This tends not to be a problem for narrow web machines but as the width of machines is increasing the opportunities for non-uniform cooling and larger thermal differences increases.  Sputtering machines are similarly affects as if the cooling is insufficient the magnets can lose performance with heat (depending on the type of magnets used) and this can become bad enough that increasing the applied power can result in a decrease in deposition rather than an increase in deposition. What happens is that the increased power leads to more bombardment of the target which leads to an increase in heating which heats up the magnets which decrease in magnetic flux which causes an increased loss of electrons and so the voltage increases and the current decreases leading to a loss of deposition rate.  This only occurs once the magnets are above a critical temperature and so for most times it is never seen. However if the water cooling flow and temperature is not controlled it can be a variable that is present but unidentified.

Hence as the trend is towards more precise deposition processes upgrading the cooling system can be a relatively simple action to take that changes an uncontrolled variable to a controlled variable.

   

Strategic goal setting.

We all work better if we have a goal to aim at.  In vacuum deposition of coatings we can have our day to day or run to run goals of producing material that is within specification. However it is always worth having a longer term goal to aim for.  Often this can be presented from on high as a directive to increase profits or reduce costs or both.  Other times this can be an initiative simply to keep the operations team focussed on product improvement and preventing the quality slipping because of complacency or disinterest.

One starting point for taking action is to define the task and this requires setting the ultimate goal.  This might be producing a specific coating that meets a specification that currently is not possible.  If we then take this coating specification and compare it to what we can produce now we can look at the differences.  This is known as doing a ‘gap analysis’ and we can then use the difference between where we are now to where we want to be to produce a ‘roadmap’ of what needs to be done to bridge the gap.  This roadmap will define each of the necessary improvements and the order in which they need to be done to be able to achieve the goal of producing the desired higher specification coating.

I doing this process we also need to do a sanity check to make sure the effort is worthwhile. Hence we should ask the questions;

Are we in time?                      

Is it feasible?

Are there sufficient resources?

What are the potential showstoppers?

 

Any of these can mean the end result will be a disappointment. If the product ends up as a ‘me too’ product and does not command a premium, or there is a real technical reason why the product cannot be produced on the equipment available, or there is no budget to facilitate any required changes will all be reasons why the initiative can fail and this will be counter productive.  The aim is to produce a roadmap of something that can be completed and deliver a benefit. Not only does this achieve the desired improvement but it also helps team working and improves motivation of operators.

 

Continuous improvement can be more challenging than simply depositing coatings.

 

 

Printed electronics and conducting inks.

            There is a large growth in the area of printed electronics.  This is because of the potential cost savings available once all the technical issues have been overcome.  The simplest sort of printed electronics that has made a significant impact on the markets has been the radio frequency identification (RFID) tags where an antenna is printed and a chip is attached to make the device. The antenna is designed with a specific pattern that is dependent upon a number of factors such as the ink conductivity, operating frequency and distance that the device will be read. However as the technology has been developed more advanced electronic devices are being developed.  Organic light emitting devices (OLEDs) have been produced that either use some printed layers in conjunction with vacuum deposited layers or have all printed layers.  The limitations for the OLEDs tend to have been the electronic performance of the materials rather than the quality of the printing. Thus the OLEDs produced with all the layers being printed have very large features, which limit the applications the OLEDs are suitable for. However as the inks are improved the feature size can be reduced and the number of applications will increase.  Photovoltaic (PV) devices can also be printed again the organic versions can have all the layers printed or can have some layers that are vacuum deposited with the rest printed.  Even the inorganic PVs can include a printed layer for the front surface contacts or can include both back and front surface contacts.  As PVs can be described electronically as a battery it is not surprising that the battery industry is also looking at printed technology as a new production process.  As this printing technology expands other materials and applications are being drawn into the technology all with the attraction of reducing costs by using an atmospheric roll-to-roll process.     

            This printing technology can be perceived as a threat to vacuum coated electronic products or as a complimentary technology depending on your viewpoint.  A copper circuit has a higher conductivity than a copper filled printed ink for the same thickness.  The ink has copper particles loaded into the ink and as the ink dries the copper particles get close enough together to form a conducting path. The conductivity is limited by the resistance of the contact between each of the particles which is always worse than for solid copper or vacuum metallized copper and so to get an equivalent conductivity the ink thickness tends to have to be much higher often 10x greater, or more.  The conductivity of the ink is dependent on the resistance of the contacts between the particles and so the size and shape of the particles and the packing density can affect the ink performance. A simple way of looking at this is to imaging the conducting particles as being spheres and then between any two points there will be a number of particles that relates to the particle size and the resistance of the organic ink and the thickness of the residual ink between particles will define the conductivity.  One way of improving the conductivity is to reduce the number of contacts and so between two points oriented acicular or cylindrical particles aligned with the long axis between the two points would reduce the number of particles required and hence reducing the number of high resistance contacts.  Similarly if this is extended to two dimensions the use of flat platelets or flakes of conducting material will reduce the number of contacts and again be an improvement in the conductivity for the same ink thickness when compared to spherical particles of the same material.

            This then provides an opportunity for vacuum metallizing as one of the ways of producing flake materials is to vacuum metallize the conducting material onto a carrier substrate with a release layer coating so that the metallized material can then be passed through a solvent stripping bath. The release layer will allow the metal layer to separate from the substrate and the very thin metal layer can then be extracted from the solvent. This material will have a wide range of aspect ratios and so will then be ground and sized to produce the flake filler to be added to make the conducting inks. However this is a high cost process and needs to be justified.  Currently this process is being used to make very high reflectivity aluminium inks. The flatness of the flake compared to ball milled aluminium flake or ball milled and ground aluminium flake is superior and the inks is brighter and more reflective.  With simple conductivity it will depend on what other manufacturing processes are available to make acicular or flake materials and how important it is to reduce the ink thickness in the final printed devices.  The materials used for conducting inks include carbon, copper, silver, aluminium, silver-aluminium, indium tin oxide, fluorine doped tin oxide, as well as speciality materials such as the copper indium gallium diselenide (CIGS) for the active layer in some PVs.

            There will also remain some applications where the required conductivity has to be higher than can be obtained by inks for a give thickness. These electronic tracks can still be produced by vacuum metallizing. These layers can be either simple metallized rolls of material or can be patterned. The patterning can be produced by pre or post patterning or in-vacuum pattern metallizing.  Although patterning has been done for some years there is a new impetus as the opportunities and technical requirements for in-vacuum pattern metallizing opens the door to new business opportunities.  The circuit line widths that can be produced are now down to 30 microns will work continuing to reduce this still further.  As these circuits need to have multiple layers there is also the requirement that the layers are kept in-register to one another. This adds to the complexity of the vacuum deposition process. Currently only Bobst GVE have solved this and again the resolution is limited to large feature sizes.  Now they have produced production equipment they will now be able to refine the technology and the resolution will improve and the feature sizes will reduce making the technology suitable for more applications.

            Hence vacuum deposited coatings for electronics still have a number of things that can be offered that will have advantages over printed electronics.     

Tension – why and how much tension to use.

Tim Walker writing in http://www.convertingblog.com and on his website www.webhandling.com covers topics such as winding and tensioning in detail and is a good source of additional information.

If we start by asking why do we tension the web?  Generally it is to help overcome the variations in the web.  Few, if any, webs are perfectly flat and parallel and free from curvature and so without tension the web would tend to wander.  By adding some tension the web can then be forced to wind straight throughout the winding system. The tension makes the web perform as if it was stiffer and this also improves the web’s ability to resist wrinkling.  This only works if the web variations are relatively small. If the thickness variations or curvature is too much then it may be possible to pull enough tension to make the curvature disappear or the fluting associated with gauge bands to disappear but it may also put a permanent distortion into the web as it exceeds the yield stress of the material.

This then leads on to the question of how much tension should be used?   In theory you might think that so long as you work below the yield stress of the web it will be acceptable.  However in vacuum metallizers the yield stress is not always a value that is known precisely. The yield stress is dependent upon the temperature and, as we all know, as the metal is deposited the web temperature rises and so the yield stress falls. What we usually do not know with any kind of precision is the maximum temperature that the web reaches. Thus we need to make an estimate of the maximum temperature and then work below this value to give some safety factor.   Again the quality of the web becomes a factor as curvature or gauge bands can create regions with tensions of more than five times higher than the average tension.  Typically a set-point of 10% of the web yield stress is a good starting point.  This may need to be modified downwards if the deposition temperature is very high or increased if the web leaves the deposition zone wrinkled.  We use the tension to hold the web hard against the cooled deposition drum to help keep the temperature down.  As the web heats it expands and so relaxes some of the tension and so the cooling is less efficient. However the is a balance as pulling more tension can improve the cooling but too much tension on the hot web could cause the yield stress to be exceeded particularly on a short edge or gauge band.

This is primarily for the tension pulled around the deposition drum. If your winding system has the tensions for the unwind, deposition and rewind zones separated then it is possible to run with a slightly higher tension for the unwind and rewind zones. Although this needs care as there is no air entrainment to separate the web layers in the rewind roll and so this roll will always be wound very hard and so does not really want to be wound with high tension as this can cause other problems such as blocking or core crushing.

In many instances the tension you apply is the minimum you can get away. The problem of this is that this minimum will be slightly different for virtually every web because of the natural manufacturing variations that lead to profile and curvature variations. Thus the tension used is often something above the minimum so that it can become a constant value for all rolls of that material and thickness.

 

Which method is the best for hologram applications

I would like to know which method is the best for hologram applications :

 

- Direct Metallizing

OR

- Transfer Metalization

Regarding

- Brightness

- Cost

- Durability

Could you please comment ?

 

 

Answer.

 

The starting point must be the paper substrate.  Paper can be metallized but there are a number of considerations that have to be made.  Paper relies on the moisture content for some of its mechanical performance. The moisture content can vary considerably and so the vacuum pumping system has to be designed to cope with the highest possible water content which can be in excess of 20%.  The winding system will also have to cope with the paper as it becomes more fragile as the moisture content is reduced by the vacuum system. This is particularly true if the moisture content of the paper is low before the paper enters the vacuum system. If the paper dries out too much it becomes very fragile and is then much more prone to web breaks.  The reflective quality of the metallized paper depends largely on the surface roughness of the paper. Thus the grade of paper becomes important as the metallized surface has to be treated essentially to smooth the surface as much as possible if you want to produce a highly reflective metallized end product.   The metallized layer is likely to contain slightly more oxygen than if the metallization was done onto a polymer film. This is simply because of the higher background levels of water that will be present in the vacuum system.  Paper that has passed through a vacuum system is often re-hydrated, to restore the mechanical properties, before post processing.

 

It is possible to either use one of the surface smoothing layers to emboss into. Alternatively an additional coating can be used at the time of embossing.

 

 

Transfer metallization requires a polymer substrate with a release layer coated prior to metallization. The transfer process can be done hot or cold depending on the adhesive used. What is also required is some pressure to make sure there is sufficient contact to the adhesive and substrate. This pressure can be high and can cause some degradation of the holographic embossing which can result in some loss of brightness.  The aluminium brightness is usually higher than that of directly metallized paper but the difference is small and although measurable is usually not noticeable to most observers. 

 

If you are buying a metallizer from new then the cost of a metallizer for paper is likely to be slightly more expensive than one for polymer because of the heavier rolls and higher pumping requirements. 

 

Durability is more dependent on the total structure. The transfer metallized material will have some protection of the hologram because some of the release layer will remain with the metallized layer when it is transferred.  The directly metallized aluminium onto the paper may be left with the aluminium exposed or may have a protective polymer layer over coated.  Transfer metallizing usually means that the whole surface does not require metallizing or require a holographic design applied across the whole surface.  This would imply that the metallized paper would require printing after metallization to blank out areas of metal. This allows a protective layer to also be applied to the metal coating at the same time.  Transfer metallizing is designed to only place metallized, holographic devices onto areas where they are required. As such the efficient use of material can be improved.  This can allow the use of 150mm wide webs for embossing and metallizing. For example Bobst GVE produce a Holosec metallizer that is specifically designed for metallizing standard 150mm wide (6 inch wide) embossed holographic reels which are regarded as an industry standard width. This type of metallizer is a much lower cost machine than a full width paper metallizer.

 

If however the end product requires metallizing to provide some oxygen or water vapour barrier performance then the full width metallizing has the advantage over the transfer metallizing process.

 

The problem of cost is impossible for me to answer without having all the information on the final product, volumes, size, performance, etc as well as then costing all the systems required.  The first step is to decide on what you want the final product to be and to then plot out the equipment required for each process to achieve the required end product. It will then be possible to evaluate what equipment you already have and what additional equipment you need.  Once this is done it will then be possible to build up a cost model for each process and compare the cost per unit item.

 

I hope that the above information helps. 

    

Caterpillar earth moving equipment & vacuum metallizers.

            What, I hear you ask, have Caterpillar earth moving machines to do with vacuum deposition systems.  Good question.   There has been a huge amount written about re-cycling polymer films including metallized films. To try to keep up-to-date I was reading various articles about re-cycling and came across one that not only included the product produced on the machines but also included the machines that the products were made on.

            Typically machines are run into the ground.  Sometimes they are refurbished once or even several times, others are maintained just enough to keep them running for as long as possible. Eventually a decision will be made to end their life and they get scrapped.  At this point they are either dumped and left to rust or stripped and the metal recovered.

            What this article was suggesting was that this need not be the end of the equipment. It was suggested that most equipment contains sufficient large basic components that could form the base for a complete re-build.  One of the examples given was of Caterpillar, who recovered more than 60,000 tonnes of equipment in 2008 and who then were able to utilise 93% of the recovered material.  The article was not detailed enough to find out all the information as to what the 93% did or did not include.  To me the figure of 93% sounds high but if this was purely on a weight basis then it might be more understandable as the engine and gearbox with its relatively high number of moving parts represents only a very small fraction of the total weight of these earth moving machines where the rest of the metal work is substantial.  I would expect that much of the large metal items do not wear out but may start to look aesthetically tired (a fancy way of saying tatty).  

What, as a buyer of one of these re-built machines, I might have a concern about would be some of the longer term failures that might occur such as fatigue failures.  This type of failure can occur even in substantial metal components simply because of the large repetitive stressing and a small imperfection that can grow with time. Having metal that has been through one lifetime of work already could mean buying material that is so much closer to the point of failure.  Bringing this philosophy back to vacuum coating systems I would have specific concern with re-using a vacuum vessel that has already seen one working life. Vacuum vessels are repeatedly stressed as the vacuum is pulled and released and the welds that are present on most vacuum systems are prone to fatigue failure.  It is common for old machines to have had welds re-done as they have failed in service, sometimes on more than one occasion.  However I am sure that this problem could be addressed by a combination of testing, rework, warranty and price.

            So should old vacuum metallizers be scrapped or re-built?  I can see the argument for re-building them but this does impose various constraints that may make the process more difficult to achieve than it first appears.  The trend is for metallizers to accept longer webs and wider webs.   Thus a machine that is built in one decade is likely to be too small to be ideal for the market a couple of decades later.  Using a machine that is smaller than the current standard can increase costs and make the product uncompetitive.  Thus I think the practicality of rebuilding machines is the easier part of the process with the more difficult part being the economics.  There are things that could be done to make the width better by using an extension ‘tube’ to the chamber and wider rolls but there is little that can be done for the web length.  Increasing the width does add a further problem of what to do about increasing the pumping.  As you can see rebuilding can also require an amount of re-designing. Technology will also have progressed and unless the system have been systematically upgraded then all the up-grades of winding and motor technology, operating system and software will be required.  The costs and time associated with recovering the machine, stripping and assessing the quality of material, to decide what can be re-used and what needs to be replaced, look as if they could be at least as long as designing and building from new.  This would suggest that there would be no financial advantage to re-building but only a way to re-cycle old metallizers. This would then need a detailed carbon footprint assessment to see which would be preferable, re-working to re-build or to simply scrap the metals for re-processing.

            Caterpillar has the advantage that their equipment is sold in much larger numbers and so they have been able to develop a complete business for recovering machines in large numbers.  Compare this to vacuum metallizers that have very limited numbers of systems sold each year and this then makes developing a business for re-building or re-furbishing metallizers more difficult.  Thus from what initially looked to be an interesting opportunity that might provide a greener route to disposing of old metallizers I think I have argued myself out of it being a practical proposition.  If I also consider that many of the metallizers that are scrapped by one company may well be shipped to Asia and kept running for many more years the benefits of re-building become even less clear.       

Bio-polymers, recycling, disposal, etc.

            There are all kinds of pressures encouraging everybody to go green but the whole area is fraught with confusion.  One example of this is in the area of biodegradable polymers.  The aim of a biodegradable polymer is that when it is disposed of it goes into a compost heap or digester so that it can be broken down quickly.  This is not the same as it being discarded and ending up in a landfill site.  Landfill disposal will mean that the polymer is likely still to be identifiable for future archaeologists to look at because landfill sites are designed to be fairly dry and with little microbial activity.  The biggest problem is not which polymer to use or how to process it but is how to get the end user to recognise the best way to dispose of the material and to then dispose of it in that way.  As I take an interest in materials, the problems of packaging and green technology I think of myself as reasonably good about taking packages apart and disposing of the bits in separate ways however even I get discouraged by having to search for the logo that tells me the polymer type and match this up with the list of which materials I can recycle and which I cannot and which have to be composted.  I am sure that in the future, as the technology improves, the labelling will be clearer and the collection will become comprehensive with the sorting done automatically. 

            In the mean time I keep looking at some of the developments and am curious how they will work out in the future.  I think that many people around the world have been shocked at the rise sharp rise in food prices caused in no small part by the switch by some farmers from growing food to growing crops for bio-fuel or bio-polymer feedstock.  The rise in oil prices suddenly created an imperative to find an alternative which caused big companies and governments to subsidise and offer high prices to encourage farmers to grow the necessary crops to evaluate these alternatives to oil.  This process was duplicated in many countries causing a large reduction in food production and hence the sharp rise in food prices. 

            Since then the price of oil has fallen back considerably there is a relaxing of the urgency in some quarters to finding a replacement to oil and so there may well be a reduction in the higher prices for the bio-fuel and bio-polymer feed stock and as the food prices have been raised there may well be some farmers who switch back to food production.  No doubt over the next few years this oscillation will reduce and stabilise but not without hardship for many of the worlds poor.  I now find myself with a dilemma of choosing between encouraging bio-raw materials and in so doing causing a food price rise or being a Luddite and continuing to squander the declining oil reserves.  

            The good news is that there are some intermediate actions that I know can help such as minimising the use of packaging as well as encouraging the better use of materials.  Many packaging materials are aimed at the lowest cost rather than the most ideal green solution.  Multilayer materials are often used to minimise the material thickness with suitable other properties but this may mean they cannot be re-cycled. Encouraging matched packaging materials, which can be re-cycled; even though they may not be the cheapest solution can be a better long term ecological solution.

            What looks to be part of the problem is that all the parts of the materials chain are separate.  The polymer manufacturers sell polymer film to converters who convert the films into the end packages for their customers who then sell the packaged products to shops who sell them on to customers who have to decide how to dispose of the packaging.  Were there to be a single manufacturer and converter for the whole process from start to finish so that the polymer manufacturer were also responsible for the final film disposal they might chose to make the disposal easier by making sure the package could be fully re-cycled.  However with so many different interested parties, all needing to remain profitable, it is easy to see how the end result can be different than if the whole process is viewed holistically.

               As we approach 2009 I look forward to yet another interesting year bringing forth yet another raft of ideas for new packaging solutions. Some of which will be good and some of which may look good initially but will be shown to be flawed and yet some others that will prove to be terrible.  The net result will be progress but always slower than expected.