Safe Handling of Polyisocyanates in Spray Application

July 2011 version

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We Take Responsibility for Health, Safety and the Environment

ALIPA = The European ALiphatic Isocyanates Producers Association

Comprises leading European manufacturers of aliphatic isocyanates and polyisocyanates

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Aliphatic Polyisocyanates

Aliphatic polyisocyanates play a dominant role as hardeners for 2-pack coatings.

The resulting aliphatic PUR (polyurethanes) coatings are characterizedby high quality, excellent durability combined with a very good drying performance.

The main benefits given by aliphatic polyurethane coatings are:

Therefore, aliphatic polyurethane coatings are used to answer to the highest requirements in terms of chemical and technical performance.

UV and weathering resistance: exceptional gloss retention and non-yellowing, even after a very long exposure time

Excellent balance between hardness and flexibility:

Outstanding chemical resistance

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Where Are 2-Pack PUR Coatings Used?

Due to their outstanding properties they are dominant in high-end applications:

• Automotive coatings (OEM) and car repair.• Transportation such as aerospace, railway equipment, trucks and buses. • Agricultural, construction and earth moving machinery. • Plastic coatings: bumpers etc.• Wood Coatings• Anticorrosive or marine paints

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Most Important Aliphatic PolyisocyanatesIdealized Structures

Aliphatic polyisocyanates are dominantly based on HDI (hexamethylene diisocyanate) or IPDI (isophorone diisocyanate).

Biuret

Isocyanurate

Uretdione

Allophanate

N

N

N

O

OO

RNCO

R ROCN NCO

NH

R

N

O

O

O

R'

ROCN

NCO

NH

NH

N

O

O

R

R

ROCN

NCO

NCO

N N

O

O

R ROCN NCO

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Polyisocyanate Classification & Labelling *

• Classification of all polyisocyanates

• May cause sensitisation by skin contact

• Labelling of all polyisocyanates (on the package)

• Symbol : Xi

• Risk phrases : R 43

Specific polyisocyanates may bear additional

classification and labelling due to irritating

properties and/or harmful effect to the environment.

Labelling of supplied hardeners may be different because of solvents and residual monomers

* European Legislation according to Regulation 67/548/EEC

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Polyisocyanate Classification & Labelling *

Labelling of supplied hardeners may be different because of solvents and residual monomers

* European Legislation according to Regulation (CE) No. 1272/2008 (CLP)

• Classification of all polyisocyanates• May cause an allergic skin reaction.

• Labelling of all polyisocyanates (on the package)• Signal word : Warning• Hazard statement : H 317

Specific polyisocyanates may bear additional

classification and labelling due to irritating

properties and/or harmful effect to the environment

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Aliphatic Polyisocyanates

Polyisocyanates - shouldn‘t they be safe?

• Reactive isocyanate group content is much lower than in diisocyanates.

• Significantly reduced volatility due to low vapor pressure.

But what about

• monomer content?

• applications at higher temperature or on hot surfaces?

• spray applications?

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Spray Applications

Spraying leads to aerosols of different particle sizes

The smaller the particle size

• The deeper the penetration into the respiratory tracked

• The less visible the particles

• The longer the settling times

• The higher the risk

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Spray Applications

Particle size distribution of spray aerosols depends on :

• Formulation of coating

• Method of spray application

• Conventional high pressure

• High Volume Low Pressure (HVLP)

• Airmix

• AirlessFor a given formulation the small size fraction rises

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Exposure on Spray Applications

• Main sources leading to possible exposure are:

• Overspray

• Rebounding material

• The amount of overspray and rebounding material depends on:

• Efficiency of coating applicationAirless ~ 95%

Airmix, HVLP ~ 75%

Conventional ~ 65%

• Shape and material of article to be coated

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Spray Application - Can It Be Safe?

Yes, if appropriate safety protection measures have been taken.

But, spray application without any precautions is always unsafe.

Yet, the degree of the hazard is widespread.

Protection provisions need to be adapted to the application conditions

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What to Do?

Remember, preventing exposure is the best way to protect your health.

Don’t take any risks. In doubt always take the more stringent measures.

Preventing measures:

1) Use engineering controls

2) Change work practices to reduce exposure

3) Use personal protective equipment

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Engineering Controls

• Optimize paint transfer rates by using efficient application

techniques

• Install local ventilation hoods

• Use spray booths to apply coatings

• Erect enclosures around work processes

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Engineering Controls

Advantage of engineering controls:

• Need only be installed once

• No physical burden on workers

But:

• Initial investment is required

• Proper operation and maintenance is mandatory

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Engineering Controls

Local ventilation systems or spray booths must be properly designed

• Exhausts are vented to the outside, away from air intakes for the work area

• The ventilation system does not vent back into the work area

• Spray booths have a minimum air flow of about 0.3 m/s past the painter

• The system or booth provides sufficient make-up air

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Airflow Pattern in a Spray Room/Spray Booth

The content of this transparency is based on material of the British HSE Motor Vehicle Repair Bodyshop Safety Health and Awareness Day, 2006.

This is how air actually flowsSide Door

This is what many people think

Sprayroom

Side Door

DowndraftSpraybooth

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Clearance Times of Spray Room / Spray Booth

Often it takes10+ minutes, andmaybe over 20minutes to clear the room

Spray fills the roomrapidly, propelled bythe spray gun air jetand air movement

Clearing of a booth can take up to 5 minutes

A fine mist, invisiblein normal lighting,envelopes the sprayer

The content of this transparency is based on material of the British HSE Motor Vehicle Repair Bodyshop Safety Health and Awareness Day, 2006.

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Good Working Practice for Spraying

• Never spray any paint systems in the open workshop• Uncontrolled paint spray mist will spread through a workplace

• Spraying creates a high-velocity air jet that rapidly fills a booth/room with mist

• Fine paint spray spreads, propelled by the spray gun air jet and air movement, and may envelope also the sprayer

• Fine paint spray is not visible under normal lighting

• Booths and rooms take time to clear of fine paint spray• Find out, or work out, the clearance time of your specific

booth/spray room• Do not remove respiratory protection/lift visor before booth/room has

cleared

The content of this transparency is based on material of the British HSE Motor Vehicle Repair Bodyshop Safety Health and Awareness Day, 2006.

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Good Working Practice for Spraying

• Check your spray booth/room regularly and keep it maintained, e. g.• Check negative pressure - any air leakage should be inwards• Check and replace filters (input and output) for a balance in air

exchange• Check for leakage with smoke generator• Check and clean fans, particularly extracts • Check and maintain door seals

• Develop ways of leaving, and entering, the ventilated spray booth/room safely

The content of this transparency is based on material of the British HSE Motor Vehicle Repair Bodyshop Safety Health and Awareness Day, 2006.

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Good Working Practices (General)

• Educate workers about the hazards associated with isocyanates.

• Use good hygiene practices

• Ensure that engineering controls and other equipment used to

reduce exposure are used properly

• Ensure that unprotected workers are not in an area where

products containing isocyanates are mixed or sprayed

• Ensure that spills are cleaned up quickly and properly and that

appropriate protective equipment and clothing is used when spills

are cleaned up

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Personal Protective Equipment

Protective clothing (general requirements on handling isocyanates)

•Appropriate solvent-resistant gloves (see supplier’s Safety Data Sheet)

•Suitable disposable overall that protects the arms and legs

•Disposable airtight goggles or full-face respirator masks to protect the eyes

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Personal Protective Equipment

Respiratory protective equipment• Air-supplying respirators• Air-purifying respirators

Properly operating air-supplying respirators provide the most effective type of respiratory protection.

Only air-purifying respirators with cartridges approved for organic vapors and mists should be used.

It is important to note that wearers are unlikely to know when a cartridge needs changing. Change out schedule based on a qualified calculation should be in place.

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Which Respiratory Protective Equipment to Use?How to Decide?

Measurements at the workplace give the best indications on the level of exposures and the effectiveness of protection measures.

If measurements are not possible, use suitable assessment tools to evaluate the possible exposure and the effectiveness of risk reduction measures.

In absence of officially binding OEL (Occupational Exposure Limit) values use commonly recommended workplace limits of polymeric isocyanates (see e.g. www.alipa.org or the Safety Data Sheet of your supplier).

Be aware of exposure times and exposure peaks in evaluating your preventing measures.

DON’T TAKE ANY RISKS

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General Considerations

Spray application means not only spraying, but also handling of the material, charging of the spraying equipment, rinsing of the spray guns and cleaning of the equipment.

Make sure that these activities are always done with the precautions and protections necessary for handling isocyanates (protective clothing and if needed respiratory equipment).

Don’t forget additional hazards associated with other paint components like solvents, resins or additives.

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Conclusion

Spray application of aliphatic polyisocyanates is safe if appropriate measures are in place.

By the combination of engineering controls, work practices and personal protection equipments adapted to the application conditions a risk to human health can be excluded.

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Use of Aliphatic Polyisocyanates in Home Worker Applications ?

The reactive nature of aliphatic polyisocyanates requires certain precautions and controlled conditions in handling and during application, especially in spray applications.

To ensure the safe use appropriate information, training and observance of necessary safety measures is of high importance.

This can only be achieved in industrial and professional use. It can not be guaranteed in the home worker sector.

Therefore ALIPA strongly recommends against the use of aliphatic polyisocyanates in this area.

Annex Important

information!

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Disclaimer

These product stewardship initiatives of ALIPA and its members do not exempt customers, producers and others in the supply chain from their occupational health, safety and environment duties and regulatory obligations. With respect to this, ALIPA and its associated members disclaim any liability in connection with the use of services rendered and of the related information provided. It is the responsibility of the user to verify the accuracy of the services and the related information which can be used by the user at his own risk.