General
-
Isocyanate is the functional group of
atoms –N=C=O (1 nitrogen, 1 carbon, 1 oxygen), not to be confused
with the cyanate
functional group which is arranged as –O–C≡N.
- Any
organic compound which contains an isocyanate group may also be
referred to in brief as an isocyanate.
- An
isocyanate may have more than one isocyanate group.
- An
isocyanate that has two isocyanate groups is known as a
diisocyanate.
- Diisocyanates
are manufactured for reaction with polyols in
the production of polyurethanes.
Process
-
Isocyanate is
supplied in tank trucks or drums.
-
Once a container has been
opened, care should be taken to exclude moisture.
-
The most favorable
temperature for storage is 15-35°C.
-
If stored at higher
temperatures, or if moisture is not excluded, an undesirable
increase in viscosity will occur.
-
Below 20°C, solid
crystals may form and settle out, which can alter the performance
of the product.
-
The solid crystals
contain pure MDI and in this solid form may exhibit the same
dimerization characteristics as pure MDI.
-
Unless prompt
action is taken to melt the product, subsequent dimerization
will proceed and may deteriorate the clarity and assay of the
product.
-
The shelf life of
Isocyanate is six months if the temperature is maintained at
15-35°C and moisture is excluded.
Technology
-
Polyurethane spray
technology is used for industrial applications such as belting for
mining, pipe linings for handling abrasive slurries and as
protective membranes in building.
-
The combination of
toughness and high elasticity with the capability of forming
seamless membranes is particularly useful in buildings where spray
coatings are used to seal insulated flat roofs.
-
It provides a
solvent-free ‘thick coating’, which combines excellent physical
properties, including crack bridging and waterproofing properties
as well as abrasion and chemical resistance.
Application
-
A number of different
forms of isocyanates are used in industry with MDI (diphenyl
methane di-isocyanate or methylene bisphenyl di- socyanate) and
TDI (toluene diisocyanate) being the most common.
-
TDI is used in the
production of flexible foams but it is the most volatile of the
common isocyanates, and gives off vapours at room temperatures
which are likely to cause harm to health.
-
MDI, in various grades,
is used to make foams, tough elastomers and flexible foams.
-
It is considerably less
volatile than TDI, so when used at room temperature, is regarded
as less hazardous. However, significant exposure can cause asthma,
particularly where it is sprayed or heated.
Market
- MDI and TDI are major isocyanate
varieties.
- China started the production of
MDI and TDI in the 60's.
- Units with a capacity of
several hundred tons a year were constructed in Dalian, Taiyuan
and Changzhou using the technology developed by China itself.
- Several MDI and TDI units have been
introduced from abroad since the 80's.
Entrepreneur who want the information
on Product, Technology, Process, Suppliers, Buyers,Company Profiles,
Application can E-Mail us to informer@eth.net,
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