LIGNIN BASED POLYOLS

POLYOLS A BASE DE LIGNINE

English Abstract

Certain lignins which are readily available from pulping processes function as a polyol component of an isocyanate system to make
foams and urethane plastics. Use of the lignin in this manner provides moisture and flame resistance and produces products having sufficient
rigidity. The sodium level must be controlled so that the reaction between the hydroxyl groups and the isocyanates produces products with
the optimal properties.

French Abstract

Certaines lignines qui sont facilement accessibles à partir des procédés de cuisson de la pâte à papier peuvent servir comme un constituant polyolique dans un système isocyanate pour fabriquer des mousses et des plastiques à base d'uréthane. L'utilisation de la lignine de cette façon confère une résistance à l'humidité et un caractère ininflammable et donne des produits ayant une rigidité suffisante. La concentration de sodium doit être contrôlée de manière que la réaction entre les groupes hydroxyle et les isocyanates donne des produits ayant des propriétés optimales.

Claims

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What is claimed is:
1. A composition comprising: lignin, a polyol, and an isocyanate, said polyol
is made
from ethvlene oxide.
2. A composition comprising: lignin and a polyol, wherein said polyol is able
to form a
stable blend with said lignin without phase separations.
3. A composition as claimed in claim 1 or 2 wherein said polyol is a polyether
polyol and
said polyether polyol is made from ethylene oxide.
4. A composition as claimed in claim 1 or 2 wherein said polyol is a blend and
contains a
polyester polyol.
5. A composition as claimed in claim 1 or 2 wherein said lignin is derived
from a solvent
pulping process.
6. A composition as claimed in claim I or 2 wherein said lignin is derived
from the Kraft
paper pulping process.
7. A composition as claimed in claim 1 or 2 wherein said lignin is derived
from a biomass
process.
8. A composition as claimed in claim 1 or 2 wherein said lignin is derived
from a
mechanical pulping process.
9. A composition as claimed in claim 1 or 2 wherein said lignin is derived
from a sulfite
paper pulping process.
10. A composition as claimed in claim 1 or 2 wherein the lignin is derived
from a semi-
mechanical pulp.

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11. A composition as claimed in claim 1 or 2 wherein the lignin is present in
an amount
effective to increase the hydrophobic character of a urethane foam or urethane
product formed
when the lignin-polyol mixture is reacted with isocyanates.
12. A composition as claimed in claim 1 or 2 wherein the lignin is present in
an amount
effective to increase the anti-oxidant content of the foam and improve the
flame resistance of
a urethane foam or urethane product formed when the lignin-polyol mixture is
reacted with
isocyanates.
13. The composition as claimed in claim 1 or 2, wherein said lignin is derived
from a
biomass source.
14. The composition as claimed in claim 1 or 2, wherein said lignin is derived
from an
ethanol processing facility.
15. A composition comprising: lignin, a polyol, and said lignin having an
inorganic ion,
said lignin being mixed with said polyol, said polyol is able to dissolve the
lignin to form a
stable, homogeneous blend with no phase separations; and said polyol is made
from ethylene
oxide.
16. A composition as claimed in claim 1 or 2, wherein said polyol is made from
ethylene
oxide and propylene oxide.

Description

CA 02214013 1997-08-27
WO 97/24362 PCT/US96/20140
LIGNIN BASED POLVOLS
BACKGROUND OF THE INVENTION
At the present time foams and urethane plastics are made by reacting a
polyol with an isocyanate with a functionality of at least 2 (two) or greater.
The polyol can be a polyester molecule which has at least a functionality of
at
least 2 (two) or greater. The polyol can also be a polyether polyol which is
made by reacting propylene oxide or ethylene oxide with a molecule such as
ethylene glycol or glycerine to produce molecules with various molecule
weights, which have pendant hydroxyl groups which will react with
difunctional or multifunctional isocyanates to produce a solid plastic or
foam.
However at present time in order to produce a rigid foam or a urethane plastic
it is necessary to react one part polyol with one part isocyanate. This is
because the isocyanate generally contains aromatic rings and this is what
makes the foam rigid, as well as having a high crosslink density.
Also, a major disadvantage of these high levels of isocyanate is that
when the foam is burned, high levels of toxic gases are produced which are
generally derived from the isocyanate part of the molecule. It would be a
tremendous advantage to be able to reduce the toxic fumes.
It has been discovered that by using the lignin molecule as part of the
polyol portion the significant advantages result. One is that by using the
lignin
molecule in the polyol portion of the system the amount of isocyanate can be
reduced 40% or more and still produce rigid foam. This reduces the amount of
toxic gases that are derived from the isocyanate portion of the system.
The lignin molecule is a natural phenolic type molecule that occurs in
wood, straw, sugar cane and other natural materials. Generally the majority of
4' the lignin that is produced as a byproduct of the pulping process to make
paper is just burned to recover heat value. In the United States alone over 50

CA 02214013 1997-08-27
WO 97/24362 PCT/US96/20140
2
billion pounds lignin are burned annually just for its heat value. Any lignin
from the Kraft pulping process, sulfite pulping process, semi mechanical
pulping process, thermomechanical pulping process, semi-chemical pulping
ti
process, solvent process, steam explosion pulping process and biomass
pulping process can be used.
As part of this present invention it was discovered that certain lignins
can function quite well as a polyol component for an isocyanate system, these
lignins can be used at different levels in the system depending on what final
properties of the system are desired.
The use of the lignin molecule also significantly improves the moisture
resistance of a foam, in fact when the proper level of lignin is used in a
urethane foam the urethane foam will be almost impervious to moisture even
when in direct contact with moisture. Commercial foams made with the
present polyols literally absorb moisture like a sponge. Another major
advantage of using lignin as a part of the polyol system is the flame
resistance
of the finished foam or urethane foam of urethane plastic part. This is
because
lignin acts as a natural flame retardant. However one of the major aspects of
this invention is that the lignin molecule becomes readily soluble in
polyether
polyol that is made from ethylene oxide.
This is very important because when a regular polyether polyol is made
from just propylene oxide the resulting polyol does not readily solubilize the
lignin molecule and in many cases phase separation results and does not
produce a quality urethane foam or plastic product. We have found that
ethylene oxide as a part of the polyol makes it possible to make these blends
with lignin.
What has been discovered is that where current polyether polyols only
have marginal solubility for various lignins this fact makes it very difficult
to
produce a high quality foam or urethane plastic part because the lignin will
tend to phase separate when the isocyanate is added to the lignin polyol blend
SUBSTITUTE SHEET (RULE 26)

CA 02214013 2006-11-09
3
and this makes it very difficult to make consistent physical products.
Also one of the major aspects of this invention is that in order to make high
quality urethane foams and plastic materials the amount of sodium or other
caustic
ions such as potassium that are present in the lignin can have a dramatic
effect on
the properties of the final urethane product. This is because it is a well
know fact
that materials that produce a basic pH in water can perform as very strong
catalysts
for the isocyanate hydroxyl reaction that produces the urethane linkage.
Therefore if
the sodium level is too high it will cause the reaction between the hydroxyl
groups
Io and isocyanates go too fast which can produce a very poor quality product.
It was
discovered and it is one of the major aspects of this invention to reduce the
sodium
level to levels that are low enough to make it possible to produce a useful
product
once the lignin based polyol has reacted with the isocyanate. Also high levels
of
sodium ions or other inorganic ions such as potassium will actually degrade
the foam
in time. The ash content is an effective measurement for determining the level
of
inorganic ions in the lignin.
Example I
In a suitable vessel use heat and or pressure to blend 300 parts of a lignin
produced from a solvent pulping process and 700 parts of WL-440 (a polyether
polyol that is made from a combination of propylene oxide and ethylene oxide)
with
agitation by using a suitable mixer and heat and higher pressure if necessary.
This
mixture can be heated to 2000 F. to improve the rate of solution, the mixing
is
continued until a dark solution results. What results is a liquid material
that has the
following viscosity: 1532 centistokes at 1000 F. whose viscosity will depend
on the
particular lignin that is used.
Example II
In order to make a thermosetting urethane part, 1.5 parts of the resin
solution of Example I is mixed with 1 part of Rubinate R 1840 (an ICI

CA 02214013 2006-11-09
4
product) (Rubinate is a trademark of Huntsman International Limited LLC) and
poured into a mold and allowed to harden. The mold can be heated as in a
compression mold and this will produce a very hard tough plastic. The hardness
of
the product will depend on the particular lignin used.
Example III
In order to produce a foam, 2 parts of the lignin based polyol of Example I is
premixed with 0.05 parts of water and 1 part Rubinate R1840 (Rubinate is a
trademark of Huntsman International Limited LLC) and then poured into a
suitable
io container and a free rising foam will result.
Example IV
In order to produce a low density foam, a blowing agent can be mixed with
this lignin based polyol in example I. Therefore 2 parts of lignin based
polyol of
example I is premixed with 0.6 parts of Forane 141 b, 1.1 dichloro-1-
fluroethane,
(Forane is a trademark of Arkema Corporation) then this mixture is mixed with
1
part of Rubinate R-1840 (Rubinate is a trademark of Huntsman International
Limited LLC) and then poured into a suitable container and a free rising foam
low
density will result.
Example V
In order to make a urethane coating based on the lignin based polyol of
example I, one part of the lignin based polyol of example I is mixed with 1
part of
suitable coating solvent depending on the coating application. Then this
premix is
mixed with 1 part Rubinate R-1840 (Rubinate is a trademark of Huntsman
International Limited LLC) and the resulting mixture is used to coat a variety
of
substances. The viscosity of this resulting mixture can be adjusted with
suitable
solvents depending on the final coating application.
In other embodiments, the polyol is WL-1590 (a polyol produced from
ethylene oxide and propylene oxide by Huntsman Chemical).
It is understood to those skilled in the art that Kraft lignin or other type
lignin
may be employed.