This document provides guidance on safe handling procedures for diisocyanate monomers. It discusses: 1) Classification and labeling requirements for common diisocyanate monomers like HDI, H12MDI, and IPDI which are classified as highly hazardous due to their toxicity if inhaled or through skin contact. 2) Physical and chemical behaviors of diisocyanates that can lead to high airborne concentrations and uncontrolled chemical reactions if not properly handled. 3) Health effects of diisocyanate exposure, including irritation of the eyes/skin as well as the risk of sensitization from repeated exposure which can cause occupational asthma. 4) Best practices for safe handling like using proper ventilation, personal protective

1. Safe Handling of
Diisocyanate Monomers (HDI, IPDI, H12MDI)
June 2019 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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Diisocyanate Monomers Users
Content
• Essential data
• Best practice
• When things go wrong …

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Diisocyanates are industrial intermediates for the manufacture of:
• Polyisocyanate resins (NCO-terminated, hardeners)
• Prepolymers
• Adducts
• Oligomers (e.g.biuret, isocyanurate, uretdione)
• Urethane resins (blocked or reacted isocyanate groups)
• Blocked polyisocyanates
• Polyurethanes
• Polyurethane dispersions
• Urethane acrylates
• Such products are basic components for formulating
• Paints and lacquers  Adhesives
• Sealants  Elastomers
Diisocyanate Monomers

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1,6-Hexamethylene diisocyanate (HDI)
CAS-No. 822-06-0
Isophorone diisocyanate (IPDI)
(3-Isocyanatomethyl-3,5,5-trimethyl-cyclohexylisocyanate),
mixture of cis- and trans- isomers,
CAS-No. 4098-71-9
4,4‘-Dicyclohexylmethane diisocyanate (H12MDI),
main component, mixture of isomers
CAS-No. 5124-30-1
Most Important Aliphatic Diisocyanates
OCN
NCO
CH3 CH3
CH3
NCO
OCN
CH2
OCN NCO

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Diisocyanate Classification & Labelling*
• GHS Classification of HDI
• Acute toxicity, Oral, Category 4 (H302)
• Acute toxicity, Inhalative, Category 1 (H330)
• Skin irritation, Category 2 (H315)
• Eye irritation, Category 2 (H319)
• Sensitization of the respiratory airways, Category 1 (H334)
• Sensitization of the skin, Category 1 (H317)
• Specific target organ toxicity (single exposure), Category 3 (H335)
• Labelling of HDI (on the package)
• Signal word : Danger
• Hazard statements
H302 Harmful if swallowed.
H315 Causes skin irritation.
H317 May cause an allergic skin reaction.
H319 Causes serious eye irritation.
H330 Fatal if inhaled.
H334 May cause allergy or asthma symptoms or breathing difficulties if inhaled.
H335 May cause respiratory irritation.
* European Legislation according to Regulation (EC) No. 1272/2008 (CLP) , Annex VI, Part 3, Table 3.1, modified by self
classification, if needed

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Diisocyanate Classification & Labelling*
• GHS Classification of H12MDI
• Acute toxicity, Inhalative, Category 1 (H330)
• Skin irritation, Category 2 (H315)
• Eye irritation, Category 2 (H319)
• Sensitization of the respiratory airways, Category 1 (H334)
• Sensitization of the skin, Category 1 (H317)
• Specific target organ toxicity (single exposure), Category 3 (H335)
• Labelling of H12MDI (on the package)
• Signal word : Danger
• Hazard statements
H315 Causes skin irritation.
H317 May cause an allergic skin reaction.
H319 Causes serious eye irritation.
H330 Fatal if inhaled.
H334 May cause allergy or asthma symptoms or breathing difficulties if inhaled.
H335 May cause respiratory irritation.
* European Legislation according to Regulation (EC) No. 1272/2008 (CLP), Annex VI, Part 3, Table 3.1, modified by self
classification, if needed

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Diisocyanate Classification & Labelling*
• GHS Classification of IPDI
• Acute toxicity, Inhalative, Category 1 (H330)
• Skin irritation, Category 2 (H315)
• Eye irritation, Category 2 (H319)
• Sensitization of the respiratory airways, Category 1 (H334)
• Sensitization of the skin, Category 1 (H317)
• Specific target organ toxicity (single exposure), Category 3 (H335)
• Hazardous to the aquatic environment, Category 2 (H411)
• Labelling of IPDI (on the package)
• Signal word : Danger
• Hazard statements
H315 Causes skin irritation.
H317 May cause an allergic skin reaction.
H319 Causes serious eye irritation.
H330 Fatal if inhaled.
H334 May cause allergy or asthma symptoms or
breathing difficulties if inhaled.
H335 May cause respiratory irritation.
H411Toxic to aquatic life with long lasting effects.
* European Legislation according to Regulation (EC) No. 1272/2008 (CLP) , Annex VI, Part 3, Table 3.1, modified by self
classification, if needed

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• HDI and IPDI have a significant vapour pressure
• H12MDI has a low vapour pressure but may exceed the OEL
(Occupational Exposure Limit) already at low temperatures
• Evaporation can lead to high concentration in air if uncontrolled
• Volatility and concentration in air increase rapidly with rising
temperature
Are you Aware of the Physical Behaviour of
Diisocyanates?
Saturated vapour concentration
of diisocyanates in air
(indicative values –
not true to scale)
You must always
protect yourself
against breathing
in diisocyanates

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• Will react with many compounds – especially water, alcohols incl.
polyols, amines, ammonia solutions, alkaline compounds
• Specific metal and amine compounds may speed up reaction
(catalysis)
• During reaction heat will be formed
• Higher temperatures mean faster reactions
(beware of temperatures > 40°C)
• Reaction with water will lead to formation of gases (CO2)
 Risk of dangerous pressures
Do You Know About the Chemical Behaviour of
Aliphatic Diisocyanates?

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Where Can Such Chemical Reactions Happen?
• Decontamination of drums
• Storage of polyol/diisocyanate together
• Spillage into a drain
• Bulk off-loading of wrong chemical into a bulk tank
• Diisocyanate in wet disposal drums
• High temperature operations

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Safety .....Take Care That You Care!
What percentage of all industrial accidents
is attributable to careless handling?
20, 40, 60 or 80 percent?
80%

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Typical Examples of Unsafe Behaviour

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Effects of Aliphatic Diisocyanates
on your Health
Short term / one-off exposure above safe level
• Irritates mouth, throat, lungs
• Tight chest, coughing
• Difficulty in breathing
• Eyes watering
• Itching, red skin (immediately or delayed)
• May burn
Symptoms can occur up to 24 hrs
after exposure

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Effects of Aliphatic Diisocyanates
on Your Health
Long term / repeated over-exposure from breathing or skin
contact leads to risk of sensitisation
• Skin symptoms of contact dermatitis like eczema
• Respiratory symptoms such as occasional breathing difficulties
similar to asthma, hay fever, sneezing
• When sensitised, potentially severe asthma in the case of even
low diisocyanate exposure
Sensitisation will prevent working with diisocyanates for life
Sensitisation is non-reversible and is a reaction of the
immune system. Not to be confused with irritation!

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A Few Questions on Safe Handling of
Diisocyanate Monomers
• Is the workplace clean and do you have good personal hygiene?
• Does anyone eat, drink or smoke in the workplace?
• Is there good workplace ventilation?
• Is there continuous use of the correct Personal Protective Equipment
(PPE) – including during plant maintenance?
• Do you know where to find emergency equipment?
• Are monomer levels measured in the workplace?
• Do you know and practice emergency procedures?
• Are regular health checks performed?

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Take Care of Yourself
• Avoid inhaling diisocyanates
• Avoid skin contact with diisocyanates
• Avoid eye contact with diisocyanates
• Pre-placement medical evaluation or medical surveillance
recommended or required by authorities
Take care of small spillages Continous use of PPE Medical surveillance

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Best Practice:
Ventilation
• Use closed systems as far as possible (closed reactors, pipes, ….)
• Use and place local extraction as near as possible above the source
• Use hoods for laboratory works
• Check that the extraction systems / hoods are well maintained and
are working properly

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Best Practice:
Continuous Use of the Correct PPE*
• Wear eye protection
• Wear protective gloves, clothing and boots
• In emergencies wear disposable overall and/or heavy duty apron
* Personal Protective Equipment

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Best Practice:
Respiratory Equipment
• In the event of insufficient ventilation or if in doubt, always wear
respiratory protection equipment
• Check that your respiratory equipment is properly used and well
maintained

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Best Practice:
Clean and Safe Workplace
• Keep work area clean and tidy
• Do not contaminate the area by the use of contaminated gloves
• Know the locations of safety showers, respiratory equipment
and eyebaths
• Do not eat, drink or smoke in the workplace

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Best Practice:
Good Personal Hygiene
• Prevent skin dryness: use barrier and moisturizing creams before
starting work
• Wash with soap & water after finishing work and before eating,
drinking or smoking
• Do not use solvents for washing
• Use disposable towels
• Do not re-use contaminated clothing or gloves

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Best Practice
Even when working with closed systems certain operations
need PPE and local extractions:
• Sampling
• Feeding
• Maintenance work
• Emptying /decontamining drums
• Handling waste

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When Things Go Wrong …
• You are trained in handling diisocyanates
• You know all the safety precautions to protect yourself
and the environment
But let's be honest… an accident can happen!
What then?

25. Spillage!
How to Deal with It?
• Evacuate area
• Put on PPE including self-contained breathing apparatus
• Prevent the diisocyanate entering drains
• Cover spillage with fire extinguishing foam to prevent escape of the
diisocyanate vapours
• Control spill with wet sand absorbent
• Use decontamination solution
• Put contaminated sand in steel drums (max 2/3 full). Leave open to
prevent pressure build up (CO2 gas) and monitor emissions
• Close drum only when temperature is low enough
• Treat as a diisocyanate waste
• Measure the diisocyanate levels in the atmosphere
Not all of these measures may be necessary for small spillages
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26. Spillage!
Be sure to Know Where to find Emergency
Equipment
• Decontamination solution
• Shovels
• Brushes and waste container
• Absorbent material such as sand
• PPE (Personal Protective Equipment)
◦ Respiratory protection
◦ Overalls/coveralls
◦ Impermeable boots
◦ Gloves
◦ Face and eye protection
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• Speed is essential
• Practice how to carry out first aid procedure
• Seek medical advice
Remember:
Prepared in and used to best practice,
you will not panic.
Emergency Procedures

28. Emergency!
How about First Aid Equipment?
• Know where your first aid equipment is
• Know what to do
• Know who to tell
• Shower
• Soap
• Clean running water is best
• Eyebath or eye wash bottle
• Telephone number of doctor
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29. Emergency Procedures:
First Aid
• Force open the eyelids
• Flush with lots of water for at least 15 minutes
• If in doubt keep flushing
• See eye specialist as soon as possible
• Immediately remove contaminated clothing
• Immediately wash skin
Wash, wash, wash – with soap and water
• Go outside into fresh air
• Doctor must be called or patient taken to
medical facility
If more information is needed contact your supplier
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30. Emergency Procedures:
Fire!
Follow your normal factory emergency procedure.
It may include:
• Sound alarm
• Evacuate, according to Seveso Directive
• Use trained specialists to fight fire
• Ensure protection from emissions
• Remember diisocyanate fires are not self-extinguishing
• Danger Boiling Liquid Expanding Vapour Explosion
(BLEVE)
Do not use water as extinguishing media
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Now Give your Knowledge a Test
What would you do if:
• A diisocyanate pump which is being serviced is still
mistakenly under pressure. A technician is sprayed in
the face with the diisocyanate?
• A maintenance worker is replacing a pump.
Why should he need skin and respiratory protection?

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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.