Note: Descriptions are shown in the official language in which they were submitted.
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Monomer-poor Polyurethane Bonding Agent Having an Improved
Lubricant Adhesion
This invention relates to a polyurethane binder and to processes for
producing a low-viscosity polyurethane binder containing isocyanate
groups which only has a low content of readily volatile residual monomers,
essentially forms no "migrates" and shows improved lubricant adhesion.
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, for example, paper, plastic
and/or aluminium, 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 compounds, 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 prepolymers,
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.
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In practice, however, chain-extending reactions are impossible to
suppress completely, even in the last case mentioned, with the result that,
on completion of the reaction, a certain 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
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excess of monomeric polyisocyanates which are incorporated in the
coating or bond (reactive diluent) in the course of a subsequent
curing/hardening process (after the addition of a hardener or by curing
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
p rod a ct.
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
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of 2500 mPas, 7150 mPas and 9260 mPas at high temperatures (75°C and
90°C). Lubricant compatibility is not mentioned
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.
Hitherto unpublished German patent application DE 197 49 834.5
relates to low-monomer polyurethane binders, disclosing a two-component
polyurethane binder with a low monomer content and a low migrate
content.
Films used, for example, for the packaging of foods frequently have
a high content of lubricants. A typical lubricant is, for example, erucic acid
amide (EAA) which is often present in the film in quantities of more than
about 400 ppm. Conventional adhesives used for bonding such films to
form laminates often show a deterioration in laminate adhesion with
increasing lubricant content of the film to be bonded. With modern efficient
packaging machines, an increase in productivity is achieved by
considerably increasing the operating speed of the machines. The films
used for this purpose generally have a distinctly increased lubricant content
- often of 600 ppm or more - in relation to relatively slow packaging
machines. Unfortunately, many conventional adhesives show
unsatisfactory adhesion on films with a lubricant content of this order. As a
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result, laminated films thus produced often show inadequate sealing seam
adhesion, above all after curing.
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
readily volatile isocyanate should be less than about 0.1 % by weight.
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 process for the production of a polyurethane binder having the properties
mentioned above.
Yet another problem addressed by the invention was to provide a
polyurethane binder and an adhesive which, besides the above-mentioned
properties in regard to its content of readily volatile isocyanates and a low
migrate content, would additionally have improved lubricant compatibility,
i.e. for example improved laminate adhesion or improved sealing seam
adhesion in the bonding of films with a high lubricant content.
The present invention relates to a polyurethane binder with a low
content of readily volatile isocyanate-functional monomers at least
containing components A, B and C, 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, at least one
polyurethane prepolymer containing at least two differently attached
types of isocyanate groups or two different polyurethane prepolymers
containing at least two differently attached types of isocyanate groups
in pairs of which at least one type has a lower reactivity to isocyanate-
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reactive groups than the other type(s), and
b) an at least difunctional isocyanate which does not contain one
nitrogen atom that is not part of an NCO group, or a mixture of two or
more thereof, is present as component B and
c) an at least difunctional isocyanate or a mixture of two or more
isocyanates with an average functionality of at least two which
contains at least one nitrogen atom that is not part of an NCO or
urethane group per isocyanate molecule is present as component C.
"Low viscosity" in the context of the present invention means a
(Brookfield) viscosity at 50°C of less than 5,000 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
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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 150
to about 15,000 or in the range from about 500 to about 10,000, for
example of the order of 5,000, but especially in the range from about 700 to
about 2,500.
In a preferred embodiment of the invention, the polyurethane
prepolymer containing two isocyanate groups or at least one of the
polyurethane prepolymers present in the mixture of polyurethane
prepolymers containing two or more 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 polyurethane 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, for example, in such a way that, on
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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.
In another preferred embodiment, mixtures of two or more different
polyurethane prepolymers may be used as component A. The mixtures
mentioned may be polyurethane prepolymers in which individual
polyurethane molecules carry identically attached isocyanate groups.
Accordingly, at least two different types of polyurethane molecules differing
at least in the nature of the isocyanate groups they carry must be present in
the mixture. In this embodiment, at least one more reactive and one less
reactive type of isocyanate groups, i.e. a polyurethane molecule containing
at least two reactive isocyanate groups and a polyurethane molecule
containing at least two less reactive isocyanate groups, must be present in
the mixture as a whole. Besides molecules containing one or more
identically attached isocyanate groups, the mixture may also contain other
molecules which carry both one or more identically attached isocyanate
groups and one or more differently attached isocyanate groups.
Component A or at least part of component A may also be formed,
for example, by the reaction products of difunctional or higher alcohols with
an at least equimolar quantity (based on the OH groups of the difunctional
or higher alcohol) of low molecular weight diisocyanates with a molecular
weight of up to about 400.
In a preferred embodiment, the polyurethane prepolymer used as
component A or the mixture of two or more polyurethane prepolymers
contains at least one urethane group per molecule.
In another preferred embodiment of the invention, component A is
prepared by an at least two-stage reaction in which
to about 15,000 or in the range
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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.
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 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.
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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
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,
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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 and/or trimethylol propane, pentaerythritol or sugar
alcohols, 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 5,000
are particularly suitable. According to the invention, polypropylene glycol
with a molecular weight of about 300 to about 2,500 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 a 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-
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.
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
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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 and/or 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
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
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about 400 to about 2,500 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
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. Polyaceta~s 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
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the polymerization of cyclic acetals.
Other suitable polyols for the production of component A 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.
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
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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
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.
The polyurethane binder according to the invention contains an at
least difunctional isocyanate which does not contain one nitrogen atom that
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is not part of an NCO group or a mixture of two or more thereof as
component B.
Component B may be formed, for example, by at least difunctional
isocyanates or by a mixture of two or more isocyanates with an average
functionality of at least about two.
In a preferred embodiment of the invention, component B contains at
least one at least difunctional isocyanate of which the NCO groups are
more reactive to NCO-reactive groups, for example in a urethanization,
thiourethanization, biuretization or allophanatization reaction, than the less
reactive isocyanate groups of the polyurethane prepolymers present in
component A.
The isocyanate groups of the difunctional isocyanates present in
component B may differ, or may be substantially identical, in their
reactivity.
In a preferred embodiment of the invention, at least difunctional
isocyanates of which the isocyanate groups are identical in their reactivity
may also be used as component B.
Component B generally has a molecular weight of up to about 2,000.
However, its molecular weight is preferably lower, for example below about
1,000, below about 700 or below about 400 glmole.
According to the invention, 4,4'-diphenylmethane diisocyanate
(MDI), 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane
diisocyanate and HDI, IPDI or TMXDI, for example, is suitable for use as
component B.
In a preferred embodiment, 4,4'-diphenylmethane diisocyanate
(MDI), 2,2'-diphenylmethane diisocyanate or 2,4'-diphenylmethane
diisocyanate are used.
The polyurethane binder according to the invention contains at least
about 3% by weight of component B, based on the polyurethane binder as
a whole. In a preferred embodiment, the polyurethane binder contains
about 5 to about 25% by weight of component B.
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WO 00/05290 17 PCTIEP99104890
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
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.
The polyurethane binder according to the invention contains an at
least difunctional isocyanate or a mixture of two or more isocyanates with
an average functionality of at least two which contains at least one nitrogen
atom that is not part of an NCO or urethane group per isocyanate as
component C.
Accordingly, the NCO-containing carbodiimides obtainable by
reaction of diisocyanates under suitable conditions and in the presence of
suitable catalysts are suitable for use in component C.
The isocyanates suitable for carbodiimide formation are, for
example, compounds with the general structure O=C=N-X-N=C=O where X
is an aliphatic, alicyclic or aromatic radical, preferably an aliphatic or
alicyclic radical conditions 4 to 18 carbon atoms.
Examples of suitable isocyanates are 1,5-naphthylene diisocyanate,
4,4'-diphenyl methane diisocyanate (MDI), hydrogenated MDI (H,2-MDI),
xylylene diisocyanate (XDI), tetramethyl xylylene diisocyanate (TMXDI),
CA 02338378 2001-O1-22
WO 00/05290 18 PCTIEP99104890
4,4'-diphenyl dimethyl methane diisocyanate, di- and tetraalkylene diphenyl
methane diisocyanate, 4,4'-dibenzyl diisocyanate, 1,3-phenylene diiso-
cyanate, 1,4-phenylene diisocyanate, the isomers of toluene diisocyanate
(TDI), 1-methyl-2,4-diisocyanatocyclohexane, 1,6-diisocyanato-2,2,4-
trimethyl hexane, 1,6-diisocyanato-2,4,4-trimethyl hexane, 1-isocyanato-
methyl-3-isocyanato-1,5,5-trimethyl cyclohexane (IPDI), chlorinated and
brominated diisocyanates, phosphorus-containing diisocyanates, 4,4'-
diisocyanatophenyl perfluoroethane, tetramethoxybutane-1,4-diisocyanate,
1,4-butane diisocyanate, 1,6-hexane diisocyanate (HDI),
dicyclohexylmethane diisocyanate, cyclohexane-1,4-diisocyanate, ethylene
diisocyanate, phthalic acid-bis-isocyanatoethyl ester; diisocyanates
containing reactive halogen atoms, such as 1-chloromethylphenyl-2,4-
diisocyanate, 1-bromomethylphenyl-2,6-diisocyanate, 3,3-bis-chloromethyl-
ether-4,4'-diphenyl diisocyanate.
Other suitable diisocyanates are, for example, trimethyl
hexamethylene diisocyanate, 1,4-diisocyanatobutane, 1,12-
diisocyanatododecane and dimer fatty acid diisocyanate. Tetramethylene,
hexamethylene, undecane, dodecamethylene, 2,2,4-trimethylhexane, 1,3-
cyclohexane, 1,4-cyclohexane, 1,3- and 1,4-tetramethyl xylene,
isophorone, 4,4-dicyclohexyl methane and lysine ester diisocyanate are
particularly suitable.
The reaction (carbodiimide formation) products of MDI, TDI, HDI or
IPDI or of mixtures of two or more thereof are especially suitable
Also suitable are the trimerization and oligomerization products of
the polyisocyanates 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 reaction are the diisocyanates
mentioned above, the trimerization products of the isocyanates HDI, MDI or
CA 02338378 2001-O1-22
WO 00105290 19 PCT/EP99104890
IPDI being particularly preferred.
Polymeric isocyanates obtained, for example, as bottom residue in
the distillation of diisocyanates are also suitable for use as component C.
The "polymeric MDI" which is obtainable from the distillation residue in the
distillation of MDI and which contains at least one nitrogen atom that is not
part of an NCO or urethane group per isocyanate molecule is particularly
suitable.
Component C is added to the polyurethane binder according to the
invention in such a quantity that the polyurethane binder as a whole
contains about 1 to about 40% by weight of component C. In a preferred
embodiment of the invention, the polyurethane binder contains about 5 to
about 30% by weight and more particularly about 10 to about 22% by
weight of component C.
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 components B and C
simultaneously or successively. Component B may optionally be added
together with another polyol component.
Accordingly, the present invention also relates to an at least three-
stage process for the production of a polyurethane binder containing
isocyanate groups, characterized in that
h) in a first stage, a polyurethane prepolymer is prepared from an at
least difunctional isocyanate and at least one polyol component
i) in a second stage, another at least difunctional isocyanate which does
not contain one nitrogen atom that is not part of an NCO group or a
mixture of two or more thereof and
CA 02338378 2001-O1-22
WO 00/05290 20 PCTIEP99104890
j) in a third stage, an at least difunctional isocyanate or a mixture of two
or more isocyanates with an average functionality of at least two is
added, at least one isocyanate containing at least one nitrogen atom
that is not part of an NCO group,
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.
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
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
CA 02338378 2001-O1-22
WO 00/05290 21 PCT/EP99/04890
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
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.
CA 02338378 2001-O1-22
WO 00105290 22 PCTIEP99/04890
To carry out the second stage of the process according to the
invention, at least one other at least difunctional isocyanate which does not
contain one nitrogen atom that is not part of an NCO group or a mixture of
two or more such isocyanates is reacted, optionally together 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 optionally present. However, a polypropylene glycol with
a molecular weight of about 400 to about 2,500 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 isocyanate groups of relatively low reactivity present
in the prepolymer is used as the at least difunctional isocyanate which does
not contain one nitrogen atom that is not part of an NCO group 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 at least a small percentage, preferably the predominant percentage, of
the isocyanate groups present in the prepolymer of component 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 which does not contain one nitrogen atom that is not part of
an NCO group.
A bicyclic aromatic symmetrical diisocyanate is preferably used as
the other at least difunctional isocyanate which does not contain one
nitrogen atom that is not part of an NCO group. The bicyclic isocyanates
CA 02338378 2001-O1-22
WO 00/05290 23 PCTIEP99104890
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 which does not contain
one nitrogen atom that is not part of an NCO group is used in the second
stage in a quantity of about 1 to about 50% by weight, preferably in a
quantity of about 10 to about 30% by weight and more preferably in a
quantity of about 15 to about 25% 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 D, E,
F and G.
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 four components D, E, F and G, characterized in that
k) an isocyanate-functional polyurethane prepolymer obtainable by
reacting a polyol component with an at least difunctional isocyanate is
used as component D,
I) another isocyanate-functional polyurethane prepolymer obtainable by
CA 02338378 2001-O1-22
WO 00105290 24 PCT/EP99/04890
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
D, is used as component E
m) an at least difunctional isocyanate which does not contain one
nitrogen atom that is not part of an NCO group or a mixture of two or
more thereof is used as component F and
n) another at least difunctional isocyanate or a mixture of two or more
isocyanates with an average functionality of at least two, at least one
isocyanate containing at least one nitrogen atom that is not part of an
NCO group, is used as component G,
the quantity of component G being gauged so that, on completion of mixing
and after all the reactions, if any, taking place between components D, E, F
and G have ended, at least 5% by weight and more particularly at least
10% by weight - based on the polyurethane binder as a whole - of
component G 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).
I n the context of the present invention, the expression "all the
reactions, if any, taking place between components D, E, F and G" refers to
reactions of isocyanate groups with functional groups containing
isocyanate-reactive hydrogen atoms. The addition of component F,
particularly when components D or E or D and E, for example, contain free
OH groups, generally leads to a reaction of the isocyanate groups of
component F with the free OH groups. This results in a reduction in the
content of component F. Accordingly, if reactions capable of leading to a
reduction in the proportion of component F are likely to occur, component F
CA 02338378 2001-O1-22
WO 00/05290 25 PCT/EP99/04890
must be added in such a quantity that, after all these reactions have ended,
the required minimum quantity of component F is present in the polyure-
thane binder.
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 D and E 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 F which does not
contain one nitrogen atom that is not part of an NCO group or a mixture of
two more such isocyanates.
The foregoing observations on component C apply similarly to the
least difunctional isocyanate or a mixture of two or more isocyanates with
an average functionality of at least two - at least one isocyanate containing
at least one nitrogen atom that is not part of an NCO group - to be used as
component G.
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
CA 02338378 2001-O1-22
WO 00/05290 26 PCT/EP99/04890
binders produced by the process according to the invention have a
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
CA 02338378 2001-O1-22
WO 00/05290 27 PCTIEP99/04890
produced in accordance with the invention in heat-sealing processes is
between about 30 and about 90°C.
The present invention also relates to an adhesive containing two
components H and I,
o) 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 H and
p) a compound containing at least two functional groups reactive to the
isocyanate groups of component H with a molecular weight of up to
50,000 or a mixture of two or more such compounds being used as
component I.
Accordingly, any of the polyurethane binders according to the
invention as described in the foregoing may be used as component H.
A compound containing at least two functional groups reactive to the
isocyanate groups of component F with a molecular weight of up to 2,500
or a mixture of two or more such compounds is preferably used as
component I. 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 I is
generally at least about two. Component I 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 I is for
example about two (for example when only difunctional compounds are
used as component I) or more, for example about 2.1, 2.2, 2.5, 2.7 or 3.
CA 02338378 2001-O1-22
WO 00/05290 28 PCT/EP99/04890
Component I may optionally have an even higher functionality, for example
of about 4 or higher.
Component I preferably contains a polyol carrying at least two OH
groups. Any of the polyols mentioned in the foregoing are suitable for use
in component I providing they satisfy the limiting criterion of the upper
molecular weight limit.
Component I is generally used in such a quantity that the ratio of
isocyanate groups of component H to functional groups reactive with
isocyanate groups of component H in component I 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 diphenyl
phosphate, polyethylene glycols and derivatives thereof, for example,
diphenyl ethers of polyethylene glycol), liquid resin derivatives, for
CA 02338378 2001-O1-22
WO 00/05290 29 PCT/EP99/04890
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 sterically 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-hydroxybenzyl)-benzene; pentaerythritol tetrakis-3-(3,5-ditert.
butyl-4-hydroxyphenyl)-propionate; n-octadecyl-3,5-ditert.butyl-4-hydroxy-
phenyl)-propionate; 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
phosphonates; 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 ethylenelvinyl acetate (EVA), ethylene/acrylic acid, ethylenelmeth-
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,
CA 02338378 2001-O1-22
WO 00/05290 30 PCT/EP99/04890
which increase the wettability of the adhesives.
The following Examples are intended to illustrate the invention
without limiting it in any way.
Examples
Explanationf the raw materials and abbreviations in Table
o 1:
A1-A5 : adhesive formulations 1 to 5
H : hardener (polyol mixture), OHV = 138.8
PE1 : polyether based on propylene glycol
PE 2 : polyether based on propylene glycol
DEG : diethylene glycol
PES : polyester based on adipic acid, diethylene
glycol,
phthalic acid and dipropylene glycol with 2
OH groups
PE3 : polyether based on propylene glycol
MDI-C : MDI carbodiimide dimer
HDI-T : HDI trimer
HDI-O : HDI oligomer
MDI-P : polymeric MDI (distillation bottom residue)
ADR-1 : OH:NCO addition ratio for component A and
component B
ADR-T : total OH:NCO addition ratio
V : viscosity (Brookfield RVTD, 40C)
MC : monomer contents in % by weight (based on
formulation as a whole)
m-TDI : monomeric TDI
m-MDI : monomeric MDI
OHV : OH value in [mg KOH/g]
NCO value : NCO content in % by weight (based on formulation
as
a whole)
NCO-F : final NCO content
CA 02338378 2001-O1-22
WO 00/05290 31 PCT/EP99/04890
Table 1.
Adhesive formulations (all figures - % by weight unless otherwise
indicated)
Raw OHV or A1 A2 A3 A4 A5 H
materials NCO value
PE1 111 29.4 29.4 29.4 29.4 29.4
PE2 267 9.8 9.8 g.8 9.8 9.8
DEG 1056 4.9 4.9 4.9 4.9 4.9 1.8
PES 108 93.0
PE 3 373 5.2
TDI 48.3 25.6 24.9 24.9 24.9 24.9
M D I 33.4 30.9 20.0 20.0 20.0 20.0
MDI-C 33 13.1
HDI-T 21 20.6
HDI-0 21.9 19.8
MDI-P 31 14.0
NCO-F 14.0 13.5 13.3 13.1 14.3
ADR-1 1.6 1.6 1.6 1.6 1.6
ADR-G 2.76 2.76 2.76 2.76 2.76
V [mPas]
40C 2700 4450 6000 5300 4320
50C 1200 1800 2550 1970 1790
60C 550 956 1200 950 790
m-TDI 0.03 0.03 0.07 0.07 0.09
m-MDI 30 24 16 14 20
CA 02338378 2001-O1-22
WO 00105290 32 PCTIEP99/04890
Explanations and abbreviations in Table 2:
E1-8 : Examples 1 to 8
C1-2 : Comparison Example 1 and 2
LS : laminate structure
F1 : 12 p thick polyethylene terephthalate (PETP)
film
F2 : 70 p thick polyethylene (PE) film with a plasticizer
content of 400 ppm erucic acid amide (EAA)
F3 : 60 p thick polyethylene (PE) film with a plasticizer
content of 800 ppm erucic acid amide (EAA)
(EAA) LA laminate adhesion
:
SSA : sealing seam adhesion
coh. AS cohesive adhesive splitting
:
adh. alt. alternating adhesion, adhesion failure takes
: place
alternately at both materials
The mixing ratio of adhesive preparation to hardener was 1:1 in E1
to E8 and 100:70 in C1 and C2.
In all Examples, the quantity applied was 2 g/m2.
CA 02338378 2001-O1-22
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