Note: Descriptions are shown in the official language in which they were submitted.
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Polyurethane Binding Agents Having a Low Content of Highly Volatile
Monomers
This invention relates to a polyurethane binder and to processes for
producing a low-viscosity polyurethane binder containing isocyanate
groups which, despite its low viscosity, only has a low content of readily
volatile residual monomers and essentially forms no "migrates". The
invention also relates to the use of a low-viscosity polyurethane binder
containing isocyanate groups (NCO groups) in the production of adhesives,
more particularly one-component and two-component adhesives, for
example for bonding web-form materials of paper, plastic or aluminium or
mixtures of two or more thereof, coatings, more particularly lacquers,
emulsion paints and casting resins as well as moldings.
Isocyanate-terminated polyurethane prepolymers have been known
for some time. They may readily be chain-extended or crosslinked with
suitable hardeners, usually polyhydric alcohols, to form high molecular
weight materials. Polyurethane prepolymers have acquired significance in
many fields of application, including for example the production of
adhesives, coatings, casting resins and moldings.
In order to obtain isocyanate-terminated polyurethane prepotymers,
it is standard practice to react polyhydric alcohols with an excess of
polyisocyanates, generally at least predominantly diisocyanates. Molecular
weight can be controlled at least approximately through the ratio of OH
groups to isocyanate groups. Whereas a ratio of OH groups to isocyanate
groups of, or approaching, 1:1 leads to generally high molecular weights, a
statistical average of one diisocyanate molecule - where diisocyanates are
used - is attached to each OH group where the OH : isocyanate group ratio
is about 2:1, so that ideally no oligomerization or chain extension occurs in
the course of the reaction.
In practice, however, chain-extending reactions are impossible to
suppress with the result that, on completion of the reaction, a certain
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quantity of the component used in excess is left over irrespective of the
reaction time. If diisocyanate, for example, is used as the excess
component, a generally considerable proportion of this component remains
behind in the reaction mixture for the reasons explained above.
The presence of such components is particularly problematical when
they consist of readily volatile diisocyanates. The vapors of these diisocya-
nates are often harmful to the skin and the application of products with a
high content of such readily volatile diisocyanates requires elaborate
measures on the part of the user to protect the people involved in
processing the product, more particularly elaborate measures for keeping
the surrounding air clean to breathe.
Since protective measures and cleaning measures generally involve
considerable expense, there is a need on the part of the user for products
which have a low percentage content of readily volatile diisocyanates
depending on the isocyanate used.
In the context of the present invention, "readily volatile" substances
are understood to be substances which have a vapor pressure at around
30°C of more than about 0.0007 mmHg or a boiling point of less than
about
190°C (70 mPa).
If low-volatility diisocyanates, more particularly the widely used
bicyclic diisocyanates, for example diphenyl methane diisocyanates, are
used instead of the readily volatile diisocyanates, polyurethane binders with
a viscosity normally outside the range suitable for simple processing
methods are generally obtained. In cases such as these, the viscosity of
the polyurethane prepolymers can be reduced by adding suitable solvents
although this is not consistent with the absence of solvents normally
demanded. Another way of reducing viscosity without solvents is to add an
excess of monomeric polyisocyanates which are incorporated in the
coating or bond (reactive diluent) in the course of a subsequent
curinglhardening process (after the addition of a hardener or by curing
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under the influence of moisture).
Whereas the viscosity of the polyurethane prepolymers can actually
be reduced in this way, the generally incomplete reaction of the reactive
diluent often leads to the presence in the bond or coating of free
monomeric polyisocyanates which are capable of "migrating", for example
within the coating or bond or, in some cases, even into the coated or
bonded materials themselves. Corresponding constituents of a coating or
bond are often referred to among experts as "migrates". By contact with
moisture, the isocyanate groups of the migrates are continuously reacted to
form amino groups. The aromatic amines normally formed in this way are
suspected of having a carcinogenic effect.
Migrates are often not tolerable, above all in the packaging field,
because any migration of the migrates through the packaging material
would result in contamination of the packaged product and the consumer
would inevitably come into contact with the migrates when using the
product.
Accordingly, the migrates in question are undesirable above all in
the packaging field, especially in the packaging of foods.
In order to avoid the disadvantages described above, EP-A 0 118
065 proposes producing polyurethane prepolymers by a two-stage process.
In the first stage of this process, a monocyclic diisocyanate is reacted with
a polyhydric alcohol in an OH group : isocyanate group ratio of <1 and, in
the second step, a bicyclic diisocyanate is reacted with polyhydric alcohols
in an OH group : isocyanate group ratio of <1 in the presence of the
prepolymer prepared in the first step. A ratio of OH groups to isocyanate
groups of 0.65 to 0.8:1 and preferably 0.7 to 0.75:1 is proposed for the
second stage. The prepolymers obtainable in this way still have viscosities
of 2500 mPas, 7150 mPas and 9260 mPas at high temperatures (75°C and
90°C).
DE-A 34 01 129 relates to a process for the production of mixed
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polyurethane prepolymers in which polyhydric alcohols are first reacted
with the faster reacting isocyanate group of an asymmetrical diisocyanate,
the more slowly reacting group being left intact, after which the reaction
products are combined with a symmetrical diisocyanate of which the
equally reactive isocyanate groups react more quickly than the slowly
reacting groups of the first polyfunctional isocyanate compound mentioned.
The described polyurethane prepolymers have high viscosities and hence
high processing temperatures so that they can only be used under
conditions which allow high processing temperatures.
EP-A 0 019 120 relates to a two-stage process for the production of
elastic weather-resistant sheet-form materials. In the first stage of this
process, toluene diisocyanate (TDI) is reacted with at least equimolar
quantities of a polyol and the reaction product obtained is subsequently
reacted with diphenyl methane diisocyanate (MDI) and a polyol. The poly-
urethane binders obtainable in this way are said to be capable of curing
with water or with atmospheric moisture. Although the described process
does give products with a relatively low viscosity, the content of free
readily
volatile diisocyanate (in the present case TDI) is still high (0.7% by weight)
and can only be reduced when time-consuming and energy-intensive
methods, for example thin-layer distillation, are used to remove excess
readily volatile diisocyanate.
In many cases, laminated films are used in applications involving
elevated temperatures, for example in the preparation of foods. Unfortu-
nately, laminated films produced with conventional adhesives often under-
go delamination whenever they are exposed to the temperatures normally
prevailing in the preparation of foods.
Accordingly, the problem addressed by the present invention was to
provide a polyurethane binder which would have a low viscosity and a low
residual content of less than about 1 % by weight of readily volatile diiso-
cyanates. In the case of toluene diisocyanate (TDI), the residual content of
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readily volatile isocyanate should be less than about 0.1 % by weight.
Another problem addressed by the present invention was to provide
a polyurethane binder which would enable processing to be carried out at
low temperatures.
A further problem addressed by the present invention was to provide
a polyurethane binder which would have a low percentage content of
"migrates", i.e. a low percentage content of monomeric polyisocyanates.
Another problem addressed by the present invention was to provide
a polyurethane binder with which it would be possible to produce laminated
films which would have little or no tendency to delaminate, even at high
temperatures.
Finally, another problem addressed by the present invention was to
provide a process for the production of a polyurethane binder having the
properties mentioned above.
The present invention relates to a polyurethane binder with a low
content of readily volatile isocyanate-functional monomers at least
containing components A and B, in which
(a) a polyurethane polymer containing at least two isocyanate groups or a
mixture of two or more polyurethane prepolymers containing at least
two isocyanate groups is present as component A, the polyurethane
prepolymer containing two isocyanate groups or the mixture of two or
more polyurethane prepolymers containing isocyanate groups
containing at least two differently attached types of isocyanate groups
of which at least one type has a lower reactivity to isocyanate-reactive
groups than the other type(s), and
(b) an at least difunctional isocyanate, of which the molecular weight is
lower than the molecular weight of the polyurethane prepolymers
present in component A and of which the isocyanate groups have a
higher reactivity to isocyanate-reactive compounds than the type of
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isocyanate groups of relatively low reactivity present in component A, is
present as component B.
"Low viscosity" in the context of the present invention means a
(Brookfield) viscosity at 50°C of less than 5000 mPas.
In the context of the present invention, the expression "polyurethane
binder" is understood to be a mixture of molecules each containing at least
two isocyanate groups, in which the content of molecules with a molecular
weight of more than 500 is at least about 50% by weight and preferably at
least about 60% by weight or about 70% by weight.
A polyurethane prepolymer containing at least two isocyanate
groups or a mixture of two or more polyurethane prepolymers containing at
least two isocyanate groups, which may preferably be obtained by reacting
a polyol component with an at least difunctional isocyanate, is used as
component A.
In the context of the present invention, a "polyurethane prepolymer"
is understood to be the compound which is obtained, for example, when a
polyol component is reacted with an at least difunctional isocyanate.
Accordingly, the expression "polyurethane prepolymer" encompasses both
compounds of relatively low molecular weight, as formed for example in the
reaction of a polyol with an excess of polyisocyanate, and also oligomeric
or polymeric compounds. The expression "polyurethane prepolymer" also
encompasses the compounds formed, for example, in the reaction of a
trihydric or tetrahydric polyol with a molar excess of diisocyanates, based
on the polyol. In this case, one molecule of the resulting compound carries
several isocyanate groups.
Molecular weights relating to polymeric compounds represent the
number average molecular weight (Mn), unless otherwise indicated.
In general, the polyurethane prepolymers used for the purposes of
the present invention have a molecular weight in the range from about 500
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to about 15,000 or in the range from about 500 to about 10,000, for
example of the order of 5000, but especially in the range from about 700 to
about 2500.
The polyurethane prepolymer containing two isocyanate groups or
the mixture of two or more polyurethane prepolymers containing isocyanate
groups has at least two differently attached types of isocyanate groups, of
which at least one type has a lower reactivity to isocyanate-reactive groups
than the other type or the other types of isocyanate groups. Isocyanate
groups with a relatively low reactivity to isocyanate-reactive groups (by
comparison with at least one other isocyanate group present in the poly-
urethane binder) are also referred to hereinafter as "less reactive
isocyanate groups" while the corresponding isocyanate group with a higher
reactivity to isocyanate-reactive compounds is also referred to as the "more
reactive isocyanate group".
According to the present invention, therefore, a difunctional
polyurethane prepolymer for example containing two differently attached
isocyanate groups, one of the isocyanate groups having a higher reactivity
to isocyanate-reactive groups than the other isocyanate group, may be
used as component A. A polyurethane prepolymer such as this may be
obtained, for example, from the reaction of a dihydric alcohol with
compounds containing two different, for example difunctional, isocyanate
groups, the reaction being carried out in such a way that, on average, each
molecule of the dihydric alcohol reacts with one molecule of the
compounds containing different isocyanate groups.
A trifunctional or higher polyurethane prepolymer may also be used
as component A, in which case one molecule of the polyurethane
prepolymer for example may contain a different number of less reactive
and more reactive isocyanate groups.
Mixtures of two or more polyurethane prepolymers may also be used
as component A in accordance with the invention. The mixtures mentioned
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may be polyurethane prepolymers in which individual molecules carry
identically attached isocyanate groups, at least one more reactive and one
less reactive isocyanate group having to be present in the mixture as a
whole. Besides molecules containing one or more identically attached
isocyanate groups, the mixture may contain other molecules which carry
both one or more identically attached isocyanate groups and one or more
differently attached isocyanate groups.
Besides component A, the polyurethane binder according to the
invention contains an at least difunctional isocyanate of which the
molecular weight is lower than the molecular weight of the polyurethane
prepolymers present in component A and of which the isocyanate groups
have a higher reactivity to isocyanate-reactive compounds than the less
reactive type of isocyanate groups present in component A.
In general, component B has a molecular weight of up to about
1000, molecular weights of up to about 720 or lower, for example of the
order of 550, 500, 450, 400 or lower, being preferred. Component B may
consist, for example, of low molecular weight diisocyanates with a
molecular weight of up to about 300 or of the reaction products of dihydric
or higher alcohols with an at least equimolar quantity of such low molecular
weight diisocyanates, based on the OH groups of the dihydric or higher
alcohol. Also suitable as component B are, for example, the trimerization
products of difunctional isocyanates, the isocyanurates.
The polyurethane binder according to the invention contains at least
5% by weight of component B, based on the polyurethane binder as a
whole.
The polyurethane binder according to the invention preferably has a
content of readily volatile isocyanate-functional monomers of less than 2%
by weight or less than 1 % by weight or preferably less than 0.5% by weight.
These limits apply in particular to readily volatile isocyanate compounds
which have only a limited danger potential for people involved in their
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processing, for example isophorone diisocyanate (IPDI), hexamethylene
diisocyanate (HDI), tetramethyl xylylene diisocyanate (TMXDI) or cyclo-
hexane diisocyanate. In the case of certain readily volatile isocyanate
compounds, especially those which represent a serious risk to people
involved in their processing, their content in the polyurethane binder
according to the invention is preferably less than 0.3% by weight and more
preferably less than 0.1 % by weight. These particular isocyanate
compounds include, above all, toluene diisocyanate (TDI). In another
preferred embodiment of the invention, the polyurethane binder has a TDI
and HDI content of less than 0.05% by weight.
In one preferred embodiment of the invention, the polyurethane
binder according to the invention may contain an at least trifunctional
isocyanate as component H in addition to components A and B.
Suitable at least trifunctional isocyanates are, for example, the
trimerization and oligomerization products of the above-mentioned poly-
isocyanates which can be obtained by suitably reacting polyisocyanates,
preferably diisocyanates, to form isocyanurate rings. If oligomerization
products are used, those which have a degree of oligomerization of on
average about 3 to about 5 are particularly suitable.
Isocyanates suitable for the production of trimers are the diisocya-
nates mentioned above, the trimerization products of the isocyanates HDI,
MDI or IPDI being particularly preferred.
Polymeric isocyanates obtained, for example, as residue in the
distillation of diisocyanates are also suitable for use as component H. The
polymeric MDI obtainable from the distillation residue in the distillation of
MDI is particularly suitable.
In one preferred embodiment of the invention, Desmodur N 3300,
Desmodur N 100, the IPDI-trimeric isocyanurate T 1890 (products of Bayer
AG) or triphenyl methane triisocyanate, for example, is used as component
H.
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Component H is preferably used in a quantity of about 1 to about
30% by weight and more preferably in quantity of about 5 to about 25% by
weight, for example in a quantity of about 12 to about 20% by weight.
In one preferred embodiment of the invention, component A is
prepared by an at least two-stage reaction in which
(c) in a first stage, a polyurethane prepolymer is prepared from an at least
difunctional isocyanate and at least a first polyol component, the
NCO:OH ratio being smaller than 2 and free OH groups still being
present in the polyurethane prepolymer,
and
(d) in a second stage, another at least difunctional isocyanate is reacted
with the polyurethane prepolymer from the first stage,
the isocyanate groups of the isocyanate added in the second stage having
a higher reactivity to isocyanate-reactive compounds than at least the
predominant percentage of the isocyanate groups present in the
polyurethane prepolymer from the first stage.
In another preferred embodiment, the other at least difunctional
isocyanate is added in a molar excess, based on free OH groups of
component A, the non-OH-reactive part of the other at least difunctional
isocyanate representing component B.
In another preferred embodiment, component A is prepared by an at
least two-stage reaction in which
(e) in a first stage, a polyurethane prepolymer is prepared from an at least
difunctional isocyanate and at least a first polyol component, the
NCO:OH ratio being smaller than 2 and free OH groups still being
present in the polyurethane prepolymer,
and
(f) in a second stage, another at least difunctional isocyanate and another
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polyol component are reacted with the polyurethane prepolymer from
the first stage,
the isocyanate groups of the isocyanate added in the second stage having
a higher reactivity to isocyanate-reactive compounds than at least the
predominant percentage of the isocyanate groups present in the
polyurethane prepolymer from the first stage.
In another preferred embodiment, the other at least difunctional
isocyanate is added in a molar excess, based on free OH groups of
component A and the other polyol component, the non-OH-reactive part of
the other at least difunctional isocyanate representing component B.
According to the invention, the OH:NCO ratio in the production of
component A in the second stage is preferably about 0.001 to less than 1:1
and, more particularly, 0.005 to about 0.8:1.
In one preferred embodiment of the invention, the OH:NCO ratio in
the second stage is about 0.2 to 0.6:1.
In another preferred embodiment of the invention, the OH:NCO ratio
in the first stage is less than 1 and, more particularly, 0.5 to 0.7:1, the
described ratios optionally being maintained for the second stage also.
In the context of the present invention, the expression "polyol
component" encompasses a single polyol or a mixture of two or more
polyols which may be used for the production of polyurethanes. A polyol is
understood to be a polyhydric alcohol, i.e. a compound containing more
than one OH group in the molecule.
Various polyols may be used as the polyol component for the
production of component A. They include, for example, aliphatic alcohols
containing 2 to 4 OH groups per molecule. The OH groups may be both
primary and secondary. Suitable aliphatic alcohols include, for example,
ethylene glycol, propylene glycol, butane-1,4-diol, pentane-1,5-diol,
hexane-1,6-diol, heptane-1,7-diol, octane-1,8-diol and higher homologs or
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isomers thereof which the expert can obtain by extending the hydrocarbon
chain by one CH2 group at a time or by introducing branches into the
carbon chain. Also suitable are higher alcohols such as, for example,
glycerol, trimethylol propane, pentaerythritol and oligomeric ethers of the
substances mentioned either individually or in the form of mixtures of two or
more of the ethers mentioned with one another.
Other suitable polyol components for the production of component A
are the reaction products of low molecular weight polyhydric alcohols with
alkylene oxides, so-called polyethers. The alkylene oxides preferably
contain 2 to 4 carbon atoms. Suitable reaction products of the type in
question are, for example, the reaction products of ethylene glycol,
propylene glycol, the isomeric butane diols or hexane diols with ethylene
oxide, propylene oxide or butylene oxide or mixtures of two or more
thereof. The reaction products of polyhydric alcohols, such as glycerol,
trimethylol ethane or trimethylol propane, pentaerythritol or sugar alcohols
or mixtures of two or more thereof, with the alkylene oxides mentioned to
form polyether polyols are also suitable. Polyether polyols with a molecular
weight of about 100 to about 10,000 and preferably in the range from about
200 to about 5000 are particularly suitable. According to the invention,
polypropylene glycol with a molecular weight of about 300 to about 2500 is
most particularly preferred. Other suitable polyol components for the
production of component A are polyether polyols as obtained, for example,
from the polymerization of tetrahydrofuran.
The polyethers are reacted in known manner by reacting the starting
compound containing a reactive hydrogen atom with alkylene oxides, for
example ethylene oxide, propylene oxide, butylene oxide, styrene oxide,
tetrahydrofuran or epichlorohydrin or mixtures of two or more thereof.
Suitable starting compounds are, for example, water, ethylene
glycol, 1,2- or 1,3-propylene glycol, 1,4- or 1,3-butylene glycol, hexane-1,6
diol, octane-1,8-diol, neopentyl glycol, 1,4-hydroxymethyl cyclohexane, 2
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methyl propane-1,3-diol, glycerol, trimethylol propane, hexane-1,2,6-triol,
butane-1,2,4-triol, trimethylol ethane, pentaerythritol, mannitol, sorbitol,
methyl glycosides, sugars, phenol, isononylphenol, resorcinol, hydroqui-
none, 1,2,2- or 1,1,2-tris-(hydroxyphenyl)-ethane, ammonia, methyl amine,
ethylenediamine, tetra- or hexamethylenediamine, triethanolamine, aniline,
phenylenediamine, 2,4- and 2,6-diaminotoluene and polyphenylpolymethy-
lene polyamines, which may be obtained by anilinelformaldehyde
condensation, or mixtures of two or more thereof.
Polyethers modified by vinyl polymers are also suitable for use as a
polyol component. Products such as these can be obtained, for example,
by polymerizing styrene or acrylonitrile or mixtures thereof in the presence
of polyethers.
Other suitable polyol components for the production of component A
are polyester polyols with a molecular weight of about 200 to about 10,000
For example, it is possible to use polyester polyols obtained by reacting low
molecular weight alcohols, more particularly ethylene glycol, diethylene
glycol, neopentyl glycol, hexanediol, butanediol, propylene glycol, glycerol
or trimethylol propane, with caprolactone. Other suitable polyhydric
alcohols for the production of polyester polyols are 1,4-hydroxymethyl
cyclohexane, 2-methyl propane-1,3-diol, butane-1,2,4-triol, triethylene
glycol, tetraethylene glycol, polyethylene glycol, dipropylene glycol, poly-
propylene glycol, dibutylene glycol and polybutylene glycol.
Other suitable polyester polyols can be obtained by
polycondensation. Thus, dihydric andlor trihydric alcohols may be
condensed with less than the equivalent quantity of dicarboxylic acids
and/or tricarboxylic acids or reactive derivatives thereof to form polyester
polyols. Suitable dicarboxylic acids are, for example, succinic acid and
higher homologs thereof containing up to 16 carbon atoms, unsaturated
dicarboxylic acids, such as malefic acid or fumaric acid, and aromatic
dicarboxylic acids, more particularly the isomeric phthalic acids, such as
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phthalic acid, isophthalic acid or terephthalic acid. Citric acid and
trimellitic
acid, for example, are also suitable tricarboxylic acids. Polyester polyols of
at least one of the dicarboxylic acids mentioned and glycerol which have a
residual content of OH groups are particularly suitable for the purposes of
the present invention. Particularly suitable alcohols are hexanediol,
ethylene glycol, diethylene glycol or neopentyl glycol or mixtures of two or
more thereof. Particularly suitable acids are isophthalic acid and adipic
acid and mixtures thereof.
In a particularly preferred embodiment of the invention, polyols used
as polyol component for the production of component A are, for example,
dipropylene glycol and/or polypropylene glycol with a molecular weight of
about 400 to about 2500 and polyester polyols, preferably polyester polyols
obtainable by polycondensation of hexanediol, ethylene glycol, diethylene
glycol or neopentyl glycol or mixtures of two or more thereof and isophthalic
acid or adipic acid or mixtures thereof.
High molecular weight polyester polyols include, for example, the
reaction products of polyhydric, preferably dihydric, alcohols (optionally
together with small quantities of trihydric alcohols) and polybasic,
preferably dibasic, carboxylic acids. Instead of free polycarboxylic acids,
the corresponding polycarboxylic anhydrides or corresponding polycar-
boxylic acid esters with alcohols preferably containing 1 to 3 carbon atoms
may also be used (where possible). The polycarboxylic acids may be
aliphatic, cycloaliphatic, aromatic or heterocyclic or both. They may
optionally be substituted, for example by alkyl groups, alkenyl groups, ether
groups or halogens. Suitable polycarboxylic acids are, for example,
succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, phthalic
acid, isophthalic acid, terephthalic acid, trimellitic acid, phthalic
anhydride,
tetrahydrophthalic anhydride, hexahydrophthalic anhydride, tetrachloro-
phthalic anhydride, endomethylene tetrahydrophthalic anhydride, glutaric
anhydride, malefic acid, malefic anhydride, fumaric acid, dimer fatty acid or
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trimer fatty acid or mixtures of two or more thereof. Small quantities of
monofunctional fatty acids may optionally be present in the reaction
mixture.
The polyesters may optionally contain a small percentage of terminal
carboxyl groups. Polyesters obtainable from lactones, for example s-
caprolactone, or hydroxycarboxylic acids, for example c~-hydroxycaproic
acid, may also be used.
Polyacetals are also suitable polyol components. Polyacetals are
compounds which can be obtained from glycols, for example diethylene
glycol or hexanediol or mixtures thereof with formaldehyde. Polyacetals
suitable for use in accordance with the invention may also be obtained by
the polymerization of cyclic acetals.
Other suitable polyols for the production of components A and B are
polycarbonates. Polycarbonates may be obtained, for example, by the
reaction of diols, such as propylene glycol, butane-1,4-diol or hexane-1,6
diol, diethylene glycol, triethylene glycol or tetraethylene glycol or
mixtures
of two or more thereof, with diaryl carbonates, for example diphenyl
carbonate, or phosgene.
OH-functional polyacrylates are also suitable polyol components for
the production of component A. These polyacrylates are obtainable, for
example, by the polymerization of ethylenically unsaturated monomers
containing an OH group. Monomers such as these are obtainable, for
example, by the esterification of ethylenically unsaturated carboxylic acids
and dihydric alcohols, the alcohol generally being present in a slight
excess. Ethylenically unsaturated carboxylic acids suitable for this purpose
are, for example, acrylic acid, methacrylic acid, crotonic acid or malefic
acid.
Corresponding OH-functional esters are, for example, 2-hydroxyethyl
acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-
hydroxypropyl methacrylate, 3-hydroxypropyl acrylate or 3-hydroxypropyl
methacrylate or mixtures of two or more thereof.
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To produce component A, the corresponding polyol component is
reacted with an at least difunctional isocyanate. Suitable at least
difunctional isocyanates for the production of component A are basically
any isocyanates containing at least two isocyanate groups although, in
general, compounds containing 2 to 4 isocyanate groups, more particularly
2 isocyanate groups, are preferred for the purposes of the present
invention.
At least difunctional isocyanates suitable as the at least difunctional
isocyanate for the production of component A are described in the
following.
These at least difunctional isocyanates are, for example, ethylene
diisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diiso-
cyanate (HDI), cyclobutane-1,3-diisocyanate, cyclohexane-1,3- and -1,4-
diisocyanate and mixtures of two or more thereof, 1-isocyanato-3,3,5-tri-
methyl-5-isocyanatomethyl cyclohexane (isophorone diisocyanate, IPDI),
2,4- and 2,6-hexahydrotoluene diisocyanate, tetramethyl xylylene diiso-
cyanate (TMXDI), 1,3- and 1,4-phenylene diisocyanate, 2,4- or 2,6-toluene
diisocyanate, diphenyl methane-2,4-diisocyanate, diphenylmethane-2,2'-
diisocyanate or diphenylmethane-4,4'-diisocyanate or mixtures of two or
more of the diisocyanates mentioned.
According to the invention, other suitable isocyanates for the
production of component A are trifunctional or higher isocyanates
obtainable, for example, by oligomerization of diisocyanates. Examples of
such trifunctional and higher polyisocyanates are the triisocyanurates of
HDI or IPDI or mixtures thereof or mixed triisocyanurates thereof.
In one preferred embodiment of the invention, diisocyanates
containing two isocyanate groups differing in their reactivity are used for
the
production of component A. Examples of such diisocyanates are 2,4- and
2,6-toluene diisocyanate (TDI) and isophorone diisocyanate (IPDI). With
non-symmetrical diisocyanates such as these, one isocyanate group
CA 02309593 2000-OS-09
WO 99/24486 17 PCT/EP98/07094
generally reacts far more quickly with isocyanate-reactive groups, for
example OH groups, while the remaining isocyanate group reacts
comparatively sluggishly. Accordingly, in one preferred embodiment, a
monocyclic non-symmetrical diisocyanate containing two isocyanate
groups differing in their reactivity, as described above, is used for the
production of component A.
In one particularly preferred embodiment, 2,4- or 2,6-toluene diiso-
cyanate (TDI) or a mixtures of the two isomers, but especially pure 2,4-TDI,
is used for the production of component A.
Component B is produced using an at least difunctional isocyanate
which ensures that at least the predominant percentage of the isocyanate
groups of component B remaining after the reaction with the polyol com-
ponent is more reactive than the predominant percentage of the isocyanate
groups present in component A. Difunctional isocyanates of which the
isocyanate groups are largely identical in their reactivity are preferably
used
for the production of component B. More particularly, these difunctional
isocyanates are the symmetrical isocyanates, preferably the symmetrical,
aromatic difunctional isocyanates. In one particularly preferred embodi-
ment, the bicyclic, aromatic, symmetrical diisocyanates of the diphenyl
methane series, more particularly MDI, are used for the production of
component B.
A polyurethane binder with the advantages according to the
invention can be produced in basically any way. However, two processes
which are described hereinafter have proved to be particularly
advantageous.
For example, the polyurethane binder can be directly produced by
preparing component A and subsequently adding component B.
However, the compound required as component B may actually be
used in the preparation of component A and may be added in such an
excess that the required final content of component B is reached.
CA 02309593 2000-OS-09
WO 99/24486 18 PCT/EP98107094
Accordingly, the present invention also relates to an at least two-
stage process for the production of a low-viscosity polyurethane binder
containing isocyanate groups, characterized in that
(g) in a first stage, a polyurethane prepolymer is prepared from an at least
difunctional isocyanate and at least one polyol component
and
(h) in a second stage, another at least difunctional isocyanate or another
at least difunctional isocyanate and another polyol component is/are
reacted in the presence of the polyurethane prepolymer,
the predominant percentage of the isocyanate groups present on
completion of the first stage having a lower reactivity to isocyanate-reactive
groups, more particularly to OH groups, than the isocyanate groups of the
at least difunctional isocyanate added in the second stage and the
OH:NCO ratio in the second stage being about 0.2 to about 0.6:1.
In principle, any of the polyols component which have already been
mentioned herein may be used as the other polyol component.
In one advantageous embodiment, the OH:NCO ratio in the first
stage of the process according to the invention is less than 1:1. In one
preferred embodiment, the ratio of OH groups to isocyanate groups in the
first stage is about 0.4 to about 0.7:1 and, more particularly, more than 0.5
to about 0.7:1.
The reaction of a polyol component with the at least difunctional
isocyanate in a first stage may be carried out in any manner known to the
expert under the general rules for producing polyurethanes. For example,
the reaction may be carried out in the presence of solvents. Suitable
solvents are, basically, any of the solvents typically used in polyurethane
chemistry, more particularly esters, ketones, halogenated hydrocarbons,
alkanes, alkenes and aromatic hydrocarbons. Examples of such solvents
CA 02309593 2000-OS-09
WO 99/24486 19 PCT/EP98/07094
are methylene chloride, trichloroethylene, toluene, xylene, butyl acetate,
amyl acetate, isobutyl acetate, methyl isobutyl ketone, methoxybutyl
acetate, cyclohexane, cyclohexanone, dichlorobenzene, diethyl ketone,
diisobutyl ketone, dioxane, ethyl acetate, ethylene glycol monobutyl ether
acetate, ethylene glycol monoethyl acetate, 2-ethylhexyl acetate, glycol
diacetate, heptane, hexane, isobutyl acetate, isooctane, isopropyl acetate,
methyl ethyl ketone, tetrahydrofuran or tetrachloroethylene or mixtures of
two or more of the solvents mentioned.
If the reaction components themselves are liquid or if at least one or
more of the reaction components forms) a solution or dispersion of other
insufficiently liquid reaction components, there is no need at all to use
solvents. A solventless reaction represents a preferred embodiment of the
invention.
To carry out the first stage of the process according to the invention,
the polyol is introduced into a suitable vessel, optionally together with a
suitable solvent, and mixed. The at least difunctional isocyanate is then
added with continued mixing. To accelerate the reaction, the temperature
is normally increased. In general, the reaction mixture is heated to about
40 to about 80°C. The exothermic reaction which then begins provides
for
an increase in the temperature. The temperature of the mixture is kept at
about 70 to about 110°C, for example at about 85 to 95°C or,
more parti-
cularly, at about 75 to about 85°C, the temperature optionally being
adjusted by suitable external measures, for example heating or cooling.
Catalysts typically used in polyurethane chemistry may optionally be
added to the reaction mixture to accelerate the reaction. Dibutyl tin
dilaurate or diazabicyclooctane (DABCO) is preferably added. If it is
desired to use a catalyst, the catalyst is generally added to the reaction
mixture in a quantity of about 0.005% by weight or about 0.01 % by weight
to about 0.2% by weight, based on the mixture as a whole.
The reaction time for the first stage depends upon the polyol
CA 02309593 2000-OS-09
WO 99/24486 20 PCT/EP98I07094
component used, upon the at least difunctional isocyanate used, upon the
reaction temperature and upon the catalyst present, if any. The total
reaction time is normally about 30 minutes to about 20 hours.
Isophorone diisocyanate (IPDI), tetramethylene xylylene diisocya-
nate (TMXDI), hydrogenated diphenyl methane diisocyanate (MDIH~2) or
toluene diisocyanate (TDI) or a mixture of two or more thereof is preferably
used as the at least difunctional isocyanate in the first stage.
To carry out the second stage of the process according to the
invention, at least one other at least difunctional isocyanate is reacted with
another polyol component in admixture with component A obtained in the
first stage. Any polyol from the group of polyols listed in the foregoing or a
mixture of two or more thereof may be used as a constituent of the other
polyol component. However, a polypropylene glycol with a molecular
weight of about 400 to about 2500 or a polyester polyol with at least a high
percentage and, more particularly, a predominant percentage of aliphatic
dicarboxylic acids or a mixture of these polyols is preferably used as the
polyol component in the second stage of the process according to the
invention.
At least one polyisocyanate of which the isocyanate groups have a
higher reactivity than the majority of the isocyanate groups present in the
prepolymer is used as the at least difunctional isocyanate in the second
stage of the process according to the invention. In other words, reactive
isocyanate groups emanating from the at least difunctional isocyanate
originally used for the production of prepolymer A may be present in the
prepolymer, the only requirement in this connection being that the
predominant percentage of the isocyanate groups present in the
prepolymer A should have a lower reactivity than the isocyanate groups of
the other at least difunctional isocyanate added in the second stage of the
process according to the invention.
A bicyclic aromatic symmetrical diisocyanate is preferably used as
CA 02309593 2000-OS-09
WO 99/24486 21 PCT/EP98/07094
the other at least difunctional isocyanate. The bicyclic isocyanates include,
for example, diisocyanates of the diphenyl methane series, more
particularly 2,2'-diphenyl methane diisocyanate, 2,4'-diphenyl methane
diisocyanate and 4,4'-diphenyl methane diisocyanate. Of the diisocyanates
mentioned, diphenyl methane diisocyanate, more particularly 4,4'-diphenyl
methane diisocyanate, is particularly preferred as the other at least
difunctional isocyanate for the second stage of the process according to
the invention.
The other at least difunctional isocyanate is used in the second
stage in a quantity of about 5 to about 95% by weight, preferably in a
quantity of about 20 to about 95% by weight and more preferably in a
quantity of about 40 to about 90% by weight, based on the total quantity of
polyisocyanates used in all the stages of the process according to the
invention.
In one preferred embodiment, the OH:NCO ratio in the second stage
is about 0.2 to about 0.6:1 and, more particularly, up to about 0.5:1. By this
is meant the OH:NCO ratio of the components added in the second stage
excluding any isocyanate groups emanating from the prepolymer A.
However, a polyurethane binder with the advantages according to
the invention can also be produced by mixing individual components C, D
and E.
Accordingly, the present invention also relates to a process for the
production of a low-viscosity polyurethane binder containing isocyanate
groups with a low content of readily volatile isocyanate-functional
monomers by mixing three components C, D and E, characterized in that
(i) an isocyanate-functional polyurethane prepolymer obtainable by
reacting a polyol component with an at least difunctional isocyanate is
used as component C,
(j) another isocyanate-functional polyurethane prepolymer obtainable by
CA 02309593 2000-OS-09
WO 99124486 22 PCT/EP98/07094
reacting a polyol component with another at least difunctional
isocyanate, of which the isocyanate groups have a higher reactivity to
isocyanate-reactive groups than the isocyanate groups of component
C, is used as component D
and
(g) another at least difunctional isocyanate, of which the molecular weight
is lower than that of components C and D and of which the isocyanate
groups have a higher reactivity to isocyanate-reactive groups than the
isocyanate groups of component C, is used as component E,
the quantity of component E being gauged so that, on completion of mixing
and after all the reactions, if any, taking place between components C, D
and E have ended, at least 5% by weight and more particularly at least
10% by weight of component E is present in the polyurethane binder.
The polyurethane binders according to the invention and the
polyurethane binders produced in accordance with the invention preferably
have a viscosity of less than 5000 mPas (as measured with a Brookfield RT
DVII (Thermosell), spindle 27, 20 r.p.m., 50°C).
In the context of the present invention, the expression "all the
reactions, if any, taking place between components C, D and E" refers to
reactions of isocyanate groups with functional groups containing
isocyanate-reactive hydrogen atoms. The addition of component E,
particularly when components C or D or C and D, for example, contain free
OH groups, generally leads to a reaction of the isocyanate groups of
component E with the free OH groups. This results in a reduction in the
content of component E. Accordingly, if reactions capable of leading to a
reduction in the proportion of component E are likely to occur, component E
must be added in such a quantity that, after all these reactions have ended,
the required minimum quantity of component E is present in the polyure-
thane binder.
CA 02309593 2000-OS-09
WO 99124486 23 PCTIEP98/07094
Any of the polyols described above and mixtures of two or more of
the polyols mentioned may be used as the polyol component for the
production of components C and D in the process according to the
invention. The polyol components in particular mentioned in the present
specification as particularly suitable for the production of component A are
also preferably used in the process according to the invention.
The foregoing observations on component B apply similarly to the at
least difunctional isocyanate to be used as component E, of which the
molecular weight is lower than that of components C and D and of which
the isocyanate groups have a higher reactivity than the isocyanate groups
of component C.
In one preferred embodiment of the invention, another at least tri-
functional isocyanate may be added as component H after the two stages
already described. Suitable at least trifunctional isocyanates are the poly-
isocyanates containing at least three NCO groups described in the
foregoing or the trimerization and polymerization products of the
difunctional isocyanates mentioned above.
The polyurethane binder according to the invention and the polyure-
thane binders produced in accordance with the invention are distinguished
in particular by the fact that they have an extremely low content of readily
volatile monomers containing isocyanate groups which is less than 2% by
weight or less than 1 % by weight, less than 0.5% by weight and, more
particularly, less than about 0.1 % by weight. It is particularly emphasized
in this connection that the process according to the invention does not
require any separate process steps for removing readily volatile diisocya-
nate components.
Another advantage of the polyurethane binders produced by the
process according to the invention is that they have a viscosity which lies in
a very favorable range for processing. More particularly, the polyurethane
binders produced by the process according to the invention have a
CA 02309593 2000-OS-09
WO 99/24486 24 PCT/EP98107094
viscosity below 5000 mPas (as measured with a Brookfield RT DVII
(Thermosell), spindle 27, 20 r.p.m., 50°C).
The polyurethane binders according to the invention are suitable for
coating articles and more particularly for bonding articles either as such or
in the form of solutions in organic solvents, for example in the solvents
described in the foregoing.
Accordingly, the present invention also relates to the use of a
polyurethane binder according to the invention or of a polyurethane binder
produced by a process according to the invention in the production of
adhesives, more particularly one-component and two-component
adhesives, coatings, more particularly lacquers, emulsion paints and
casting resins as well as moldings and for coating and, more particularly,
bonding articles, more particularly for bonding films and for the production
of laminated films.
The polyurethane binder according to the invention or the polyure-
thane binder produced by one of the processes according to the invention
is used in particular for bonding plastics and, in one particularly preferred
embodiment, for laminating plastic films, plastic films metallized with metals
or with metal oxides and metal foils, more particularly aluminium foils.
The curing process, i.e. the crosslinking of the individual polyure-
thane binder molecules through the free isocyanate groups, may be carried
out solely under the influence of atmospheric moisture, i.e. without any
need to add hardeners. However, polyfunctional crosslinking agents, for
example amines or, more particularly, polyfunctional alcohols, are
preferably added as hardeners (two-component systems).
Film laminates made with the products produced in accordance with
the invention are safe to heat-seal. This is attributable to the reduced
percentage of migratable low molecular weight products in the polyure-
thane binders. A favorable processing temperature for the adhesives
produced in accordance with the invention in heat-sealing processes is
CA 02309593 2000-OS-09
WO 99124486 25 PCTIEP98107094
between about 30 and about 90°C.
The present invention also relates to an adhesive containing two
components F and G,
(i) a polyurethane binder containing isocyanate groups according to the
invention or a polyurethane binder containing isocyanate groups
produced by the process according to the invention being used as
component F
and
(j) a compound containing at least two functional groups reactive to the
isocyanate groups of component F with a molecular weight of up to
2500 or a mixture of two or more such compounds being used as
component G.
Accordingly, any of the polyurethane binders according to the
invention as described in the foregoing may be used as component F.
A compound containing at least two functional groups reactive to the
isocyanate groups of component F with a molecular weight of up to 2500 or
a mixture of two or more such compounds is preferably used as component
G. The at least two functional groups reactive to the isocyanate groups of
component F may be selected in particular from amino groups, mercapto
groups or OH groups. Compounds suitable for use in component G may
contain amino groups, mercapto groups or OH groups either individually or
in admixture.
The functionality of the compounds suitable for use in component G
is generally at least about two. Component G preferably has a percentage
of compounds with a higher functionality, for example with a functionality of
three, four or more. The total (average) functionality of component G is for
example about two (for example when only difunctional compounds are
used as component G) or more, for example about 2.1, 2.2, 2.5, 2.7 or 3.
CA 02309593 2000-OS-09
WO 99/24486 26 PCT/EP98/07094
Component G may optionally have an even higher functionality, for
example of about 4 or higher.
Component G preferably contains a polyol carrying at least two OH
groups. Any of the polyols mentioned in the foregoing are suitable for use
in component G providing they satisfy the limiting criterion of the upper
molecular weight limit.
Component G is generally used in such a quantity that the ratio of
isocyanate groups of component F to functional groups reactive with
isocyanate groups of component F in component G is about 5:1 to about
1:1 and, more particularly, about 2:1 to about 1:1.
The adhesive according to the invention generally has a viscosity of
about 250 to about 10,000 mPas and, more particularly, in the range from
about 500 to about 8000 mPas or to about 5000 mPas (Brookfield RVT
DVII, spindle 27, 20 r.p.m., 40°C).
The adhesive according to the invention may optionally contain
additives. The additives may make up as much as about 30% by weight of
the adhesive as a whole.
Additives suitable for use in accordance with the present invention
include, for example, plasticizers, stabilizers, antioxidants, dyes, photo-
stabilizers and fillers.
Suitable plasticizers are, for example, plasticizers based on phthalic
acid, more particularly dialkyl phthalates, phthalic acid esters esterified
with
a linear alkanol containing about 6 to about 12 carbon atoms representing
preferred plasticizers. Dioctyl phthalate is particularly preferred.
Other suitable plasticizers are benzoate plasticizers, for example
sucrose benzoate, diethylene glycol dibenzoate and/or diethylene glycol
benzoate, in which about 50 to about 95% of all the hydroxyl groups have
been esterified, phosphate plasticizers, for example t-butylphenyl Biphenyl
phosphate, polyethylene glycols and derivatives thereof, for example,
Biphenyl ethers of polyethylene glycol), liquid resin derivatives, for
CA 02309593 2000-OS-09
WO 99124486 27 PCT/EP98107094
example the methyl ester of hydrogenated resin, vegetable and animal oils,
for example glycerol esters of fatty acids and polymerization products
thereof.
Stabilizers or antioxidants suitable for use as additives in
accordance with the invention include hindered phenols of high molecular
weight (Mn), polyhydric phenols and sulfur- and phosphorus-containing
phenols. Phenols suitable for use as additives in accordance with the
invention are, for example, 1,3,5-trimethyl-2,4,6-tris-(3,5-ditert.butyl-4-hy-
droxybenzyl)-benzene; pentaerythritol tetrakis-3-(3,5-ditert.butyl-4-hydroxy-
phenyl)-propionate; n-octadecyl-3,5-ditert.butyl-4-hydroxyphenyl)-propion-
ate; 4,4-methylene-bis-(2,6-ditert.butylphenol); 4,4-thiobis-(6-tert.butyl-o-
cresol); 2,6-ditert.butylphenol; 6-(4-hydroxyphenoxy)-2,4-bis-(n-octylthio)-
1,3,5-triazine; di-n-octadecyl-3,5-ditert.butyl-4-hydroxybenzyl phosphon-
ates; 2-(n-octylthio)-ethyl-3,5-ditert.butyl-4-hydroxybenzoate; and sorbitol
hexa-[3-(3,5-ditert.butyl-4-hydroxyphenyl)-propionate].
Suitable photostabilizers are, for example, those marketed under the
name of Tinuvin~ (manufacturer: Ciba Geigy).
Other additives may be incorporated in the adhesives according to
the invention in order to vary certain properties. These other additives
include, for example, dyes, such as titanium dioxide, fillers, such as talcum,
clay and the like. The adhesives according to the invention may optionally
contain small quantities of thermoplastic polymers or copolymers, for
example ethylene/vinyl acetate (EVA), ethylene/acrylic acid, ethylene/meth-
acrylate and ethylene/n-butyl acrylate copolymers which optionally provide
the adhesive with additional flexibility, toughness and strength. It is also
possible - and preferred in accordance with the invention - to add certain
hydrophilic polymers, for example polyvinyl alcohol, hydroxyethyl cellulose,
hydroxypropyl cellulose, polyvinyl methyl ether, polyethylene oxide,
polyvinyl pyrrolidone, polyethyl oxazolines or starch or cellulose esters,
more particularly the acetates with a degree of substitution of less than 2.5,
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WO 99/24486 28 PCTIEP98107094
which increase the wettability of the adhesives.
The following Examples are intended to illustrate the invention
without limiting it in any way.
Examples
List of the
abbreviations
used:
DPG - dipropylene glycol
PPG - polypropylene glycol
TDI - toluene diisocyanate (2,4-isomer)
MDI - 4,4'-diphenyl methane diisocyanate
PE - polyester based on isophthalic acidladipic acid/diethylene
glycolldipropylene glycol
NCO - isocyanate group content
OHV - OH value
M - molecular weight
d - day
VH - laminate adhesion
SNH - sealing seam adhesion
OPA - oriented polyamide
PEKO$$ LLDPEILDPE blend, thickness: ca. 70 pm, manufacturer:
=
Mildenberger and Willing
Examples 1 to 9 were carried out by the following method:
The polyol components of the first stage were introduced first and
homogeneously mixed. The isocyanate was then added and the
temperature of the reaction mixture was increased to 50°C. The
temperature then rose considerably as a result of the exothermic reaction
between isocyanate groups and OH groups and, after reaching 90°C, was
kept at that level by cooling.
The components for the second stage were added to the reaction
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WO 99/24486 29 PCTIEP98/07094
product of the first stage and the mixture was adjusted to a temperature of
85°C, followed by stirring for another hour.
In Example 9, the first and second stages were separately produced
and the resulting products were subsequently mixed.
Examples 10, 11 and 12 were carried out with isophorone
diisocyanate (IPDI) as the first isocyanate component.
The results are set out in Table 1 below.
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WO 99/24486 30 PCT/EP98107094
Table 1:
Examples 1 to 12
Example 1 2 3 4 5 6
O_HV Eq__u_ivalent weight
1st Stage
TDI 19.0 18.1 17.1 19.6 22.0 17.1
PPG 10 17 12 5 3 12
PPG 8 4 8 10 8 8
DPG 4 2 3 6 8 3
PE 0 0 0 0 0 0
OH:NCO ratio 0.555 0.556 0.588 0.588 0.588 0.588
Equivalents 0.218 0.208 0.196 0.2250 0.253 0.196
NCO
Equivalents 0.121 0.115 0.116 0.1323 0.149 0.116
OH
NCO:OH ratio 1.8 1.8 1.7 1.7 1.7 1.7
Final NCO 9.9 9.4 8.5 9.6 10.7 8.5
content
Quantity 41.0 41.1 40.1 40.6 41.0 40.1
1st stage
2nd Stage
MDI 38.8 38.3 39.7 38.6 37.1 38.2
PPG 10 10 10 10 10 10
PPG 10 10 10 10 10 15
DPG 0 0 0 0 0 0
PE 10 10 10 10 10 10
OH: NCO ratio 0.29 0.294 0.284 0.292 0.303 0.2535
2nd stage
Equivalents 0.31 0.306 0.318 0.31 0.297 0.3053
NCO 2nd
stage
Equivalents 0.09 0.09 0.09 0.09 0.09 0.0774
OH 2nd stage
NCO:OH addition 3.44 3.40 3.53 3.43 3.29 3.94
ratio 2nd
stage
NCO:OH addition 2.50 2.50 2.50 2.40 2.30 - 2.60
ratio, total
-
Quantity, 109.8 109.3 109.8 109.2 108.1 108.2
total
Final NCO 12.1 11.8 11.8 12.0 12.1 12.0
Viscos.40C: 9000 9300 5800 9370 14500 4190
Viscos.50C: 3300 3530 2220 3320 4660 1770
NCO (1d) 11.80% 12% 12.1% 12.2%
MDI 17.00% 16.0% I 17.1% 16.6%
TDI I I I 0.10% 0.10% / I 0.08% 0.09% 0.1
I I I I %1
CA 02309593 2000-OS-09
WO 99124486 31 PCTIEP98/07094
Table 1 continued
Example 7 8 911 912 913
Stage Stage Mixing
1 2
SeparateSeparateof the
batch batch separate
batches
OHV Equivalent weight
1st Stage
TDI 21.7 21.7 17.1
PPG 13.5 13.5 12
PPG 25.5 25.5 8
DPG 0 0 3
PE 26.645 26.645 0
OH:NCO ratio 0.714 0.714 0.588
Equivalents 0.249 0.249 0.196
NCO
Equivalents 0.178 0.178 0.116
OH
NCO:OH ratio 1.4 1.4 1.77
Final NCO 3.4 3.4 8.5
content
Quantity 87.3 87.3 40.1
1st stage
2nd Stage
MDI 12.2 33.9 38.3
PPG 0 0 5
PPG 0 0 15
DPG 0.575 0.575 0
PE 0 0 10
OH:NCO ratio 0.088 0.032
2nd stage
Equivalents 0.098 0.271 0.3058
NCO 2nd
stage
Equivalents 0.009 0.009 0.0774
OH 2nd stage
NCO:OH addition 31.67 3.95
ratio 2nd
stage
NCO:OH addition 2.79 3.95
ratio, total
Quantity, 100.1 121.8 68.2
total
Final NCO 6.7 11.5 14.1
Viscos.40C: Viscos.20000 3470 103000 1330 4600
Viscos. 50C: Viscos.7200 1420 I I 1770
NCO (1d) 7.10% 11.10% 9.00% 14.10% 12.40%
MDI I I I 28.00% 18%
TDI / / 0.80% / 0.30%
CA 02309593 2000-OS-09
WO 99124486 32 PCTIEP98107094
Table 1 continued
Example 10 11 12
OHV Equivalent weight
1 Stage
IPDI 21.1 19.3 17.1
PPG 400 256 219 10.3 10.64 10.64
PPG 1000 113 497 19.5 7.09 7.09
DPG 836 67 0 2.66 2.66
PE 218 137 410 20.4 0 0
PE 231 110 510 0 0 0
Stanclere 0.01 0.075 0.075
TL
Equivalents 0.1905 0.1741 0.1537
NCO
Equivalents 0.1360 0.1024 0.1024
OH
Addition 1.4 1.7 1.5
ratio X:1
Final NCO 3.2 7.6 5.7
Quantity 71.3 39.7 37.4
1 st stage
2nd Stage
MDI 28.1 54.6 77.1
PPG 400 0 14.4 20.304
PPG 1000 0 15.2 21.432
DPG 0.45 0 0
PE 218 0 14.9 21.009
Equivalents 0.2249 0.4371 0.6164
NCO 2nd
stage
Equivalents 0.0067 0.1327 0.1871
OH 2nd
stage
NCO:OH addition 33.56 3.29 3.30
ratio 2nd
stage
NCO:OH addition 2.91 2.60 2.66
ratio,
total
Quantity, 99.9 138.9 177.2
total
Final NCO 11.5 11.4 11.4
Viscos.40C 6000 4910 5600
Viscos.50C 2800 1960 2120
NCO (24 11.55% 12.20% 12.10%
h)
MDI (batch) 22.70% 20.00% 20.00%
~ IPDI (batch)~ ~ <1% ~ <1% I ~1%
~
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WO 99/24486 33 PCTIEP98/07094
Table 2:
Example 13
OHV Equivalent
weight
1 st Stage
TDI 15.7
PPG 400 265 212 9.9
PPG 1000 111 506 6.6
PPG 2000 55 1020 8.58
DPG 835 67 2.502
Equivalents NCO 0.1803
Equivalents OH 0.1054
Addition ratio X:1 1.71
Final NCO 7.3
Quantity 1 st stage 43.3
2nd Stage
MDI - 31.9
PPG 400 4.104
PPG 1000 12.402
PE 218 8.208
Equivalents NCO 2nd stage 0.2552
Equivalents OH 2nd stage 0.0647
NCO:OH addition ratio 2nd 3.95
stage
NCO:OH addition ratio, 2.56
total
Quantity 1 st + 2nd stage 99.9
Final NCO 11.2
3rd Stage
Desmodur 3300 20
Equivalents NCO 3rd stage __ 0.1026
Quantity, total 119.9
Final NCO _
~ 12.9
Viscos. 40C 4200 mPas
Color clear, yellowish
CA 02309593 2000-OS-09
WO 99/24486 34 PCTIEP98/07094
Table 3: Evaluation of the lamination tests with a polyurethane binder
according to Example 6.
Table 3
Laminate Quantity Web VH unprinted SNH n115 mm
structure ' applied speed NI15 mm
glm2 mlmin.
OPAI 1.9 100 11.6 52.1
PEKOee PE elongation Internal laminate
failure
OPAI 1.5 100 11.7 55.1
PEKO88 PE elongation Laminate failure
in
edge of sealing
seam
OPAI 1.1 100 11.1 55.4
PEKOeg PE elongation Laminate failure
in
edge of sealing
seam
Migration test:
The migrate content is determined as follows (see Deutsche
Lebensmittel Rundschau, 87, (1991), 280-281):
A weldable laminated film bag made with the adhesive according to
the invention is filled with 3% acetic acid and stored for 2 h at 70°C.
The
contents of the bag are then diazotized, subjected to azo coupling with N-
(1-naphthyl)-ethylenediamine and concentrated in a C~$ column. The
concentration of azo dye is then photometrically determined. The results
are set out in Table 4 below.
CA 02309593 2000-OS-09
WO 99124486 35 PCT/EP98/07094
Table 4:
Results of the migration tests
Migrates Laminate
(after days)
01.07.97 9.7 Ng AHCU100 ml
(4 days)
9.7 Ng AHCU100 ml 07.07.973.8 Ng AHCLI100 ml
(10 days)
11.07.97 0.93 Ng AHCL/100 ml
(14 days)
21.07.97 <0.2 Ng AHCU100 ml
(24 days)
