The Changing Concerns of Filtration Efficiency

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The Changing Concerns of Filtration Efficiency

• By Dr M J Taylor
• Scientific Services Manager
• Filtrona Technology Centre

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Main Topics to be Covered

• Filtration of tobacco smoke
• Filter development
• Legislation
• New cigarette product developments
• Emerging filter products
• Future outlook
• Conclusion

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Physical Properties of Cigarette Smoke
Acetate tow microscopic structure
4
Filtration of Smoke
Filter
5
Cigarette Filters
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Smoke Composition
100
80
60
40
20
0
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Filtration of Smoke Particles
Scheme of the Three Main Different Impaction
Mechanisms
Direct interception
Diffusional deposition
Inertial impaction
Electrical effects
Negligible
Gravitational effects
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Filtration of Smoke Particles

• Filtration of smoke particles by impaction is the
  major mechanism for tar and Nicotine reduction
• But impaction only removes smoke particles and
  hence has very little effect on gas or vapour
  phase compounds such as volatile aldehydes,
  hydrocarbons and ketones
• Other filter materials such as carbon work by
  adsorption
• This is a different process to that shown by
  fibrous filter elements and does allow the
  removal of vapour phase materials

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Carbon Pore Structure
Macropore
Mesopore
Micropores
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Filtration by Adsorption on Carbon
Mesopore
Micropore
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Vapour Phase Retention
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Semi-Volatile Retention
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Filter Development

• Early filters were mainly used to keep loose
  particles of tobacco from the smokers mouth
• The role of the filter expanded and filters were
  used for tar and Nicotine reduction
• Filters became more complex and dual filters
  combining two materials were introduced
• Filters with granular additives especially carbon
  became more common
• Filters were also used as carriers for various
  flavours

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Evolution of Filter Technology

• Monofilters - Acetate and Paper
• Dual Filters - Segments in Series
• Filters with Granular Additives - Dual and
  Triples
• Ventilation starts to emerge
• Shaped Filters
• Higher Retention Monofilters (CPF)
• Filters with Flavours
• Recess Filters
• Dual Filters - Segments in Parallel (CCF)
• Selective Filters
• New Filter Developments

1950
2003
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Legislation

• Early legislation confined to maximum tar yields.
  
• For example European Union maximum tar yield in
  1993 was 15 mg
• Generally tar and nicotine yields printed on
  packets
• Only in a few countries such as Australia and the
  Gulf States were other smoke analytes considered.
  In these countries this only went as far as the
  requirement to print CO yields on the packets

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European Union Regulations for Tar, Nicotine and
CO

• 1993 15mg tar maximum.
• 1998 12mg tar maximum.
• 2004 10mg tar1mg nicotine10mg CO maximum.
• Ingredient Disclosures
• Advertising Ban
• 2007 Cigarette export delivery maximum 10110.
• Currently considering further regulations.

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Regulations implementing EU Directive 2001/37/EC

• 14 With the consequence that smokers in fact
  extract the same or nearly the same levels of
  nicotine and tar from a light cigarette as from a
  standard variety.
• It is for this reason that the Directive
  proposes a ban on misleading descriptors such as
  light and mild.
• 40 In addition to the basic provisions on the
  testing of tar, nicotine and carbon monoxide
  yields, the Directive also gives member states
  the power to require manufacturers or importers
  to test the yields of other substances produced
  by their tobacco product
• 41 In addition to requiring manufacturers to test
  the yield of substances other than tar, nicotine
  and carbon monoxide, the Directive also requires
  manufacturers to supply the government annually
  with a list of all ingredients used in the
  manufacture of their products, by brand name
  

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Americas Regulations for Tar, Nicotine and CO

• USA none.
• Canada none.
• South America
• Brazil is the only country in South America with
  current legislation
• Maximum levels in Brazil are Tar 10 mg Nicotine
  1.0 mg CO 10 mg.

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Asia Regulations for Tar, Nicotine and CO

• Malaysia Maximum yields tar 20 mg nicotine 1.5
  mg.
• Hong Kong Maximum tar yield 17 mg.
• India, Japan, Korea, Thailand and the Philippines
  no maximum values.
• China voluntary agreement only current 15 mg Tar
  maximum - 2005 12 mg.

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Other Regulations

• In some countries regulations call for a wide
  range of compounds in smoke to be measured and
  reported generally on an annual basis
• Principally in Canada and Brazil over 40
  compounds in both mainstream and sidestream smoke
  have to be measured and reported on an annual
  basis
• These compounds are often referred to as the
  Hoffmann compounds and cover a wide range
  materials in smoke from gas/vapour phase
  compounds to non-volatiles
• Many of these compounds are harmful or
  potentially carcinogenic

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Major Hoffmann Compounds

• Permanent Gasses - Carbon Monoxide, Hydrogen
  Cyanide and Nitric Oxide
• Organic Volatiles - Aldehydes (Formaldehyde,
  Acetaldehyde, Acrolein, etc), Hydrocarbons
  (Isoprene, 1,3 Butadiene, Toluene and Benzene)
  and Ketones.
• Semi-Volatiles - Bases (Pyridine and Quinoline)
  and Phenols (Phenol, o, m p-Cresol,
  Hydroquinone, Resorcinol and Catechol)
• Non-Volatiles - Tobacco Specific Nitrosamines
  (NNN, NNK, NAT and NAB), Aromatic Amines (12
  Aminonaphthalene, 34 Aminobiphenyl) and
  BenzoaPyrene

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Product Development

• Consideration of the filtration of these
  compounds has lead to the development of reduced
  exposure products.
• However, the major aim of cigarette designers is
  to reduce the yield of all the compounds on the
  list when compared to standard products
• These type of products generally combine the use
  of standard filter materials such as cellulose
  acetate with granular adsorbents such as carbon
  and others.
• A consequence of the aim to reduce these
  compounds in smoke is a large increase in
  interest in the use of carbon in filters

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New Cigarette Products

• Already a number of cigarettes have been launched
• Although most use carbon other granular materials
  are now being used

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New Cigarette Products
Emerging products Innovative filter design for
lower yield products

Activated Carbon Cavity Filter
Triple Solid Active Filter
Cellulose Acetate
Activated Carbon
Ion Exchange Resin
Cellulose acetate
Activated Carbon
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Emerging Filter Products

• The requirement for lower yielding products has
  lead to the development of new filter products to
  help meet these needs
• Some recently launched products include
• The Active Patch Filter - APF - The first
  commercial mono-carbon filter
• The HCN reducing filter - A filter which is
  highly selective towards Hydrogen Cyanide
• The COR filter - A high pressure drop low
  retention filter that allows the use of
  ventilation at acceptable cigarette draw
  resistance to reduce the yield of many smoke
  compounds

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Active Patch Filter (APF)
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Active Patch Filter

• The first commercially available mono-carbon
  filter
• Can be used to introduce activated carbon into a
  traditionally monoacetate market without the
  necessary adaptation of carbon taste

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Active Patch Filter

• Standard plugwrap for non-ventilated cigarettes
• Use on line laser to produce ventilated products
• Carbon Loading 2.9 mg per mm of filter length
• Five millimeter carbon free zone at the filter
  mouth end
• Three millimeter carbon free zone at the filter
  tobacco rod end
• Carbon loading up to 50 mg per filter

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Active Patch Filter

• Higher reductions of vapour phase and
  semi-volatiles when compared to monoacetate
• Clean run filter - No cutting of carbon segments
  during cigarette manufacture or filter transport

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Increase in Retention APF versus Monoacetate
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The HCN Filter

• Utilises a special carbon that has been
  impregnated to increase its removal of Hydrogen
  Cyanide
• Can be used in any current carbon filter design
• In properties and appearance this special
  carbon looks the same as standard coconut shell
  carbon except the much higher HCN removal

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The HCN Filter
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The HCN Filter

• The addition of the HCN removing material does
  not effect the activity of the carbon to other
  compounds in smoke
• The HCN filter gives the same or very similar
  vapour removal to other carbon filters for the
  same weight of carbon but with much higher
  Hydrogen Cyanide removal
• The activity of the filter towards Hydrogen
  Cyanide only changes slightly with either filter
  or cigarette storage time

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The HCN Filter
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The HCN Filter - Effect of Cigarette Age
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The COR Filter

• Fibrous filter materials reduce tar and Nicotine
  effectively and usually increasing pressure drop
  increases retention efficiency
• Carbon reduces vapour phase compounds
• None of the current filtration medium reduces
  permanent gasses such as Carbon Monoxide
• The only current efficient way to reduce Carbon
  Monoxide is to use ventilation

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The COR Filter

• The problem is that high levels of ventilation
  with high pressure drop/high retention filters
  produces very low tar cigarettes
• High levels of ventilation with lower pressure
  drop/lower retention filters give acceptable tar
  levels but at too low a cigarette draw resistance
• The requirement is to produce a high pressure
  drop but low retention filter
• This can then be used in a ventilated cigarette
  to give lower Carbon Monoxide yields at
  acceptable cigarette draw resistances
• Using ventilation to reduce Carbon Monoxide in
  this way also reduces the yields of other
  permanent gasses such as Nitric Oxide and many
  vapour phase compounds

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The COR Filter
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The COR Filter

• Designed as a triple construction with an acetate
  mouth end, an empty cavity (but could also
  contain carbon) and a tobacco end segment of
  acetate
• The tobacco rod acetate segment is low pressure
  drop and low retention
• The mouth end acetate segment is high pressure
  drop but low retention

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The COR Filter

• Reduction of CO yield relative to the reduction
  of tar whilst offering acceptable draw
  resistance, even with high ventilation levels
• The COR filter also reduces the deliveries of
  organic volatiles and other gas phase compounds
  such as Nitric Oxide
• Carbon could be used in conjunction with this
  filter to enhance the reduction of organic
  volatiles

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COR Filter Comparison with Monoacetate at the
same Tar Yield
Cigarette DR mm 100 Tar Yield 8 mg
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Future Outlook

• The trend towards lower yield products now seems
  firmly established
• The use of carbon will increase as more of these
  products are launched
• Other filtration medium such as Ion Exchange
  Resins and selective carbons will become
  increasing common in the future
• Many of these selective filtration medium will be
  used in conjunction with carbon in increasingly
  complex filters

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Conclusions

• Over the last 50 years the use of filters on
  cigarettes has grown so that over 95 of all
  cigarettes sold now have filters
• Early filters were relatively simple mono filters
• The filters used have generally increased in
  size, complexity and retention capability
• Complex filters are now firmly established and
  their use is expected to grow as the demand for
  reduced exposure products grows
• A wide range of filter products currently exists
  but this is expected to grow as the filter
  performance increases to meet the demands of the
  industry
• Filters in 50 years time may be degradable
  multi-segment filters with many different
  selective filtration materials

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• Thank you for your attention
• Filtrona - Delivering Solutions through Innovation