Note: Descriptions are shown in the official language in which they were submitted.
~3~!~6~6
POLYURETHANE BASED NULTI-PURPO8E HOUSEHOLD ADHESIVE
Field of the Invention
This invention relates to multi-purpose household
adhesives, also known as universal household adhesives,
which are used for bonding a number of substrates
encountered in the home, such as paper, cardboard, photo-
graphs, fabrics, leather, felt, bast, cork, films, metals
such as aluminum and iron, china, ceramics, glass, wood,
and various plastics, including for example polystyrene
foams. These adhesives are expected to produce an adequate
adhesive effect on these various substrates which differ
chemically and physically in their surface structure and
which are normally subjected to a special surface treatment
before industrial bonding.
Statement of Related Art
Compared with the large variety of classes and types
of adhesive used in industry and workshops, there are only
a few substances which are capable of meeting the stringent
demands imposed on the versatility of a multi-purpose
household adhesive. Among those substances, only polyvinyl
acetate and its copolymers are widely used - normally in
solution or, for gluing wood, in the form of a dispersion.
The demand for versatility represents a particularly
difficult selection criterion for an adhesive. Ultimately,
it means that the adhesive molecules must show high afffin-
ity for both polar and apolar interfaces. Accordingly, thestatement that a certain substance is suitable as an adhe-
sive does not indicate to one skilled in the art whether it
can also be used as a multi-purpose household adhesive.
In addition to the versatility requirement, there has
also recently been a demand for physiologically
unobjectionable, transparent, aqueous multi-purpose
household adhesives free from the odors associated with
:~3~65~
common solvent-based adhesives. However, these adhesives
are expected to produce dried films with substantial
resistance to water. In addition, these water-based
adhesives are also expected to be able to bond substrates
that are difficult to bond, such as plastics.
This requirement profile has not heretofore been fully
satisfied either by the binders hitherto preferred for
multi-purpose adhesives, namely polyvinyl acetate and vinyl
acetate copolymers, or by such alternatives as nitrocel-
lulose. Although polyvinyl acetate can be produced withoutsolvents in the form of aqueous dispersions, the disper-
sions obtained are not transparent, but milky white. They
show good performance properties when used, for example, as
wood glue. The acrylates and styrene acrylates widely used
as dispersion adhesives are also not known commercially in
the form of transparent household adhesives with the
properties mentioned.
DE-OS 15 95 602, which goes back to the year 1966,
broadly describes a process for the production of cati-
onically modified polyurethane dispersions which containquaternary ammonium groups in a quantity of at least 0.21%
as an emulsifying component. The specification names
numerous polyols, numerous isocyanate compounds, and
numerous cationic salt-forming components as modifiers.
The usual chain-extending agents are also mentioned. It is
possible by the process in question to produce optically
almost clear colloidal dispersions of aggregates which give
tack-free or tacky films. The use of the products as
adhesives is also generally mentioned without any
particulars.
The broad disclosure of DE 15 95 602 encompasses both
polyurethane dispersions, in which polyesters are used as
the OH-functional component, and also those in which poly-
ethers or polyacetals are used. However, polyurethane
dispersions based on polyurethanes synthesized from OH-
functional polyesters are not suitable as multi-purpose h-
ousehold adhesives because they undergo hydrolysis during
133965~
storage and hence do not have the required storage
stability. Polyurethane dispersions based on polyethylene
oxide and/or polypropylene oxide as OH-functional component
are also not suitable as multi-purpose adhesives because
they show poor adhesion to plastics and thus do not satisfy
the versatility requirement.
Although DE 15 95 602 mentions polytetrahydrofuran as
a possible polyol, there is no reference to the fact that
this particular polyol is a suitable basis for polyurethane
dispersions for multi-purpose household adhesives.
Published Japanese patent application No. 62(1987)-
112676 published on 23 May 1987 describes an aqueous poly-
urethane adhesive comprising a polyurethane which has been
obtained by reaction of a polytetrahydrofuran diol with a
polyfunctional isocyanate. More particularly, the
published Japanese application teaches reacting
polytetrahydrofuran diol (with a molecular weight of 400 to
2,000) with organic diisocyanates and a dimethylol alkanoic
acid, subjecting the product of this reaction to chain
extension with hydrazine and, after neutralization with a
tertiary amine, reacting the product with a water-soluble
epoxide or a water-soluble aziridine. Bonding is obtained
by crosslinking of the carboxyl-terminated polyurethane
with the polyepoxide or polyaziridine. There is no
teaching in the Japanese patent application that polyure-
thane dispersions of the type in question may be used,
without any addition of epoxide or aziridine, as multi-
purpose "single-part" household adhesives.
An object of the present invention is to provide
aqueous, transparent materials that satisfy the complex and
partly conflicting requirements mentioned above in regard
to multi-purpose household adhesives.
Description of the Invention
It has now surprisingly been found that specially
selected aqueous polyurethane dispersions are excellent
multi-purpose household adhesives. The polyurethane
dispersions according to the invention consist of adducts
133~6~6
of polyfunctional isocyanates with selected polyfunctional
hydroxy or amino compounds. The reaction products contain
co-condensed units capable of salt formation in aqueous
solution.
In particular, the adhesives useful in the present
invention include products from reaction of:
- a polyol mixture consisting completely or partly of
polytetrahydrofuran,
- a difunctional or more than difunctional isocyanate
component used in an OH:NCO ratio of 1:0.5 to 1:2.0,
preferably 1:1.0 to 1:1.7 and more preferably 1:1.05
to 1:1.6 thereto,
- a functional component capable of salt formation in
aqueous solution and
15 - optionally a chain-extending agent
as a universal household adhesive.
The polyurethanes forming the basis of the polyure-
thane dispersions used in accordance with the invention are
based on a polyol mixture consisting completely or partly
of polytetrahydrofuran, in which the polytetrahydrofuran
content, based on polyol mixtures, should be no less than
30% by weight and, preferably, no less than 70% by weight.
In the context of the invention, the term polytetrahydro-
furan applies to polyethers which may be theoretically or
actually prepared by ring-opening polymerization of tetra-
hydrofuran and have a hydroxyl group at either end of the
chain. Suitable products have a degree of oligomerization
of from approximately 1.5 to 150 and preferably from 5 to
100 .
In addition to or instead of the polytetrahydrofuran
diols, it is also possible to use the analogous compounds
in which up to 50% of the tetrahydrofuran units involved in
the synthesis of the polyols are replaced by ethylene oxide
or propylene oxide. Among these compounds, preference is
attributed to those which consist of 25 to 30 mol-% ethyl-
ene oxide units and 75 to 70 mol-% tetrahydrofuran oxide
units. In addition to the diols based on tetrahydrofuran,
:~3396S~i
the analogous diamines may also be used.
In addition, up to 70% by weight of the polytetra-
hydrofuran polyols on which the polyurethane dispersions
used in accordance with the invention are based may be
replaced by other polyols typically used in preparations of
the type in question. A general rule in this regard is
that these other polyols must contain at least two reactive
hydrogen atoms and should be substantially linear with a
molecular weight in the range from 300 to 20,000 and pref-
erably in the range from 500 to 6,000. Preferred other
polyols are polyesters, polyacetals, polyethers, polythio-
ethers, polyamides and/or polyester amides containing on
average 2 to 4 hydroxyl groups.
Suitable polyethers are, for example, the polymeriza-
tion products of ethylene oxide, propylene oxide, butyleneoxide and copolymerization and graft polymerization prod-
ucts thereof and the polyethers obtained by condensation of
polyhydric alcohols or mixtures thereof and the polyethers
obtained by alkoxylation of polyhydric alcohols, amines,
polyamines and aminoalcohols. Isotactic polypropylene
glycol may also be used.
Suitable and preferred polyacetals include the
compounds obtainable from glycols, such as diethylene
glycol, triethylene glycol, hexanediol, and formaldehyde;
and polyacetals prepared by polymerization of cyclic
acetals.
Among the polythioethers, the condensates of thiodi-
glycol alone or with other glycols, dicarboxylic acids,
formaldehyde, aminocarboxylic acids, or aminoalcohols are
suitable and preferred. Depending on the co-components,
the products are polythioethers, polythio mixed ethers,
polythioether esters, or polythioether ester amides.
Hydroxyl terminated compounds such as these may also be
used in alkylated form or in admixture with alkylating
agents.
Suitable and preferred polyesters, polyester amides,
and polyamides include the predominantly linear condensates
~3~96S6
,
obtained from polybasic, saturated and unsaturated
carboxylic acids or their anhydrides and polyhydric,
saturated and unsaturated alcohols, aminoalcohols,
diamines, polyamines, and mixtures thereof and also
polyterephthalates or polycarbonates. Polyesters of
lactones, for example caprolactone, or of hydroxycarboxylic
acids may also be used. The polyesters may contain
terminal hydroxyl or carboxyl groups. Relatively high
molecular weight polymers or condensates such as, for
example, polyethers, polyacetals, and polyoxymethylenes may
also be used as alcohol component in the synthesis of the
polyurethane dispersions used in this invention.
Hydroxyl terminated compounds and polymers already
containing urethane or urea groups and modified natural
polyols, such as castor oil, may also be used as part of
the polyol mixture, as may other compounds containing basic
nitrogen atoms such as, for example, polyalkoxylated
primary amines or polyesters or polythioethers containing
alkyl diethanolamine in co-condensed form. Polyols
obtainable by complete or partial ring opening of
epoxidized triglycerides with primary or secondary hydroxyl
compounds, for example the reaction product of epoxidized
soybean oil with methanol, are also suitable.
Suitable multifunctional isocyanates for reaction to
make dispersions according to the invention include any
aromatic and aliphatic diisocyanates such as, for example,
1,5-naphthalene diisocyanate, 4,4'-diphenylmethane
diisocyanate, 4,4'-diphenyl dimethyl methane diisocyanate,
di- and tetraalkyl diphenyl methane diisocyanate, 4,4'-
dibenzyl diisocyanate, 1,3-phenylene diisocyanate, 1,4-
phenylene diisocyanate, the isomers of tolylene diisocya-
nate, 1-methyl-2,4-diisocyanatocyclohexane, 1,6-
diisocyanato-2,2,4-trimethyl hexane, 1,6-diisocyanato-
2,4,4-trimethyl hexane, 1-isocyanatomethyl-3-isocyanato-
1,5,5-trimethyl cyclohexane, chlorinated and brominated
diisocyanates, phosphorus-containing diisocyanates, 4,4'-
diisocyanatophenyl perfluoroethane, tetramethoxy butane-
~96~û
1,4-diisocyanate, butane-1,4-diisocyanate, hexane-1,6-
diisocyanate, dicyclohexyl methane diisocyanate,
cyclohexane-1,4-diisocyanate, ethylene diisocyanate,
phthalic acid-bis-isocyanatoethyl ester, also polyisocya-
S nates containing reactive halogen atoms, such as 1-chloro-
methylphenyl-2,4-diisocyanate, 1-bromomethylphenyl-2,6-
diisocyanate, 3,3-bis-chloromethylether-4,4'-diphenyl
diisocyanate. Suitable sulfur-containing polyisocyanates
may be obtained, for example, by reaction of 2 moles of
hexamethylene diisocyanate with 1 mole of thiodiglycol or
dihydroxydihexyl sulfide. Preferred diisocyanates include
isophorone diisocyanate, which is most preferred, and
trimethyl hexamethylene diisocyanate, m-and/or p-
tetramethyl xylene diisocyanate, l,4-diisocyanatobutane,
1,2-diisocyanatododecane and dimer fatty acid diisocyanate.
The multifunctional isocyanates may be used individually or
in mixtures. Cyclic or branched aliphatic diisocyanates,
such as isophorone diisocyanate, are generally preferred.
Also suitable and of special interest are partly
masked polyisocyanates which provide for the formation of
self-crosslinking polyurethanes, for example dimeric
tolylene diisocyanate, or polyisocyanates partly reacted,
for example, with phenols, tertiary butanol, phthalimide,
and/or caprolactam.
Suitable chain extending agents containing reactive
hydrogen atoms include:
- saturated and unsaturated glycols, such as ethylene
glycol or condensates of ethylene glycol, butane-1,3-
diol, butane-1,4-diol, butenediol, propane-1,2-diol,
propane-1,3-diol, neopentyl glycol, hexanediol, bis-
hydroxymethyl cyclohexane, dioxyethoxy hydroquinone,
terephthalic acid-bis-glycol ester, succinic acid di-
2-hydroxyethyl amide, succinic acid di-N-methyl-(2-
hydroxyethyl)-amide, 1,4-di-(2-hydroxymethylmercapto)-
2,3,5,6-tetrachlorobenzene, 2-methylene propane-1,3-
diol, 2-methylpropane-1,3-diol;
- aliphatic, cycloaliphatic and aromatic diamines, such
1~96~&
as ethylenediamine, hexamethylenediamine, 1,4-cyclo-
hexylenediamine, piperazine, N-methyl propylenedi-
amine, diaminodiphenylsulfone, diaminodiphenyl ether,
diaminodiphenyl dimethylmethane, 2,4-diamino-6-phenyl
triazine; and 3,3'-dibromo-4,4'-diaminodiphenyl
methane (diamines known to be health hazards, such as
for example hydrazine, diaminodiphenyl methane, the
isomers of phenylenediamine, carbohydrazides, and
hydrazides of dicarboxylic acids are not recommended;)
10 - aminoalcohols, such as ethanolamine, propanolamine,
butanolamine, N-methyl ethanolamine, N-methyl
isopropanolamine;
- aliphatic, cycloaliphatic, aromatic and heterocyclic
mono- and diaminocarboxylic acids, such as glycine, 1-
and 2-alanine, 6-aminocaproic acid, 4-aminobutyric
acid, the isomeric mono- and diaminobenzoic acids, the
isomeric mono- and diaminonaphthoic acids; and
- water.
Suitable special chain-extending agents containing at
least one basic nitrogen atom include, for example, mono-,
bis- or polyalkoxylated aliphatic, cycloaliphatic, aromatic
or heterocyclic primary amines, such as N-methyl
diethanolamine, N-ethyl diethanolamine, N-propyl
diethanolamine, N-isopropyl diethanolamine, N-butyl
diethanolamine, N-isobutyl diethanolamine, N-oleyl
diethanolamine, N-stearyl diethanolamine, ethoxylated
coconut oil fatty amine, N-allyl diethanolamine, N-methyl
diisopropanolamine, N-ethyl diisopropanolamine, N-propyl
diisopropanolamine, N-butyl diisopropanolamine, N-
cyclohexyl diisopropanolamine, N,N-diethoxylaniline, N,N-
diethoxyl toluidine, N,N-diethoxyl-l-aminopyridine, N,N'-
diethoxyl piperazine, dimethyl-bis-ethoxyl hydrazine, N,N'-
bis-(2-hydroxyethyl)-N,N'-diethylhexahydro-p-
phenylenediamine, N-12-hydroxyethyl piperazine, polyal-
koxylated amines, such as propoxylated methyl diethanol-
amine, also such compounds as N-methyl-N,N-bis-3-aminopro-
pylamine, N-(3-aminopropyl)-N,N'-dimethyl ethylenediamine,
~3965~
N-(3-aminopropyl)-N-methyl ethanolamine, N,N'-bis-(3-
aminopropyl)-N,N'-dimethyl ethylenediamine, N,N'-bis-(3-
aminopropyl)-piperazine,N-(2-aminoethyl)-piperazine,N,N'-
bisoxyethyl propylenediamine, 2,6-diaminopyridine, dieth-
anolaminoacetamide, diethanolamidopropionamide, N,N-bis-
oxyethylphenyl thiosemicarbazide, N,N-bis-oxyethylmethyl
semicarbazide, p,p'-bis-aminomethyl dibenzyl methylamine,
2,6-diaminopyridine,2-dimethylaminomethyl-2-methylpropane-
1,3-diol.
Suitable chain-extending agents containing R-S020-
groups and/or halogen atoms capable of quaternization
include, for example, glycerol-l-chlorohydrin, glycerol
monotosylate, pentaerythritol-bis-benzenesulfonate,
glycerol monomethanesulfonate, adducts of diethanolamine
and chloromethylated aromatic isocyanates or aliphatic
haloisocyanates, such as N,N-bis-hydroxyethyl-N'-m-
chloromethyl phenylurea, N-hydroxyethyl-N'-chlorohexyl
urea, glycerol monochloroethyl urethane, bromoacetyl
dipropylene triamine, and chloroacetic acid diethanolamide.
The polyurethanes on which the polyurethane disper-
sions used in accordance with the invention are based con-
tain a functional component capable of salt formation in
aqueous solution as a necessary constituent. This
functional component may be a dihydroxy or a diamino
compound containing an ionizable carboxylic acid, sulfonic
acid, or ammonium group. These compounds may either be
used as such or they may be prepared in situ. To introduce
compounds bearing ionizable carboxylic acid groups into the
polyurethane, one skilled in the art may add dihydroxycar-
boxylic acids to the polyols. A preferred dihydroxycar-
boxylic acid is dimethylolpropionic acid.
To introduce sulfonic acid groups capable of salt
formation, a diaminosulfonic acid may be added to the
polyols. Examples are 2,4-diaminobenzenesulfonic acid and
also the N-(~-aminoalkane)-~-aminoalkanesulfonic acids
described in DE 20 35 732.
To introduce ammonium groups capable of salt formation
13~6~6
into the polymer, it is also possible in accordance with DE
15 95 602 cited above to modify the polyurethane prepolymer
with an aliphatic or aromatic diamine in such a way the
chains are terminated by primary amino groups which may
then be converted into quaternary ammonium compounds or
into amine salts with standard alkylating agents.
It is preferred to make the polyurethane prepolymers
to be used soluble in water by means of carboxylic acid or
sulfonic acid groups because polyurethane dispersions
containing anionic modifiers such as these can be removed
under alkaline conditions, i.e. adhesives of the type in
question can be removed from certain substrates, for
example from fabrics, by washing under proper conditions.
The polymers are present at least partially in salt
form in the polyurethane dispersions used in accordance
with the invention. In the case of the preferred polymers
modified with carboxylic acids or sulfonic acids, alkali
metal salts, ammonia, or primary, secondary, or tertiary
amines, are preferably present as counterions. In the
cationically modified products, acid anions, for example
chloride, sulfate, or the anions of organic carboxylic
acids, are present as counterions. The groups capable of
salt formation may be completely or partly neutralized by
the counterions. An excess of neutralizing agent is also
possible.
As already mentioned in the discussion of the chain
extending agents to be used according to the invention,
compounds which are known to be dangerous or detrimental to
health are not desirable in the adhesives. This is
especially important because the present invention provides
a very versatile adhesive which is likely be used by types
of people, such as children, the elderly, people with
illnesses, and pregnant women, whose health is particularly
at risk. Therefore in a particularly preferred embodiment,
not only the chain extending agents but also the remaining
components of the adhesive are selected in as far as
possible to be physiologically unobjectionable. In this
~3~96~6
connection for example, the partial or, if possible, total
absence of organic solvents is to be aimed at. In this
connection also, it is worth noting that the much discussed
danger to health of polyurethane adhesives containing free
isocyanate or unreacted isocyanate groups of the polymers
or prepolymers does not occur in the present invention,
because the polyurethanes are dispersed in water and the
isocyanate groups, as is known to those skilled in the art,
react very rapidly with the water. Thus it can be
guaranteed that the polyurethane dispersions according to
the invention contain no physiologically offensive reactive
NCO groups.
To produce the polyurethanes particularly suitable for
the purposes of the invention, the polyols and an excess of
diisocyanate are preferably reacted to form an isocyanate-
terminated polymer, suitable reaction conditions including
reaction times and temperatures being chosen for the par-
ticular isocyanate(s) used. One skilled in the art knows
that the reactivity of the constituents to be reacted
necessitates maintenance of a suitable balance between
reaction velocity and unwanted secondary reactions which
lead to discoloration and a reduction in molecular weight.
The reaction is typically carried out with stirring over
approximately 1 to 6 hours at approximately 50~C to approx-
imately 120DC.
The preferred production process is the so-called
acetone process described by D. Dietrich, Angew. Makromol.
Chem., 98, 133 (1981). The polyurethane dispersions used
in accordance with the invention may also be produced by
the process according to DE 15 95 602. A more recent
suitable process for the production of polyurethane
dispersions is described in DE 36 03 996 and in the prior
art cited therein, namely: DE-PS 880 485, DE-AS 10 44 404,
US-PS 3,036,998, DE-PS 11 78 586, DE-PS 1 184 946, DE-AS 12
37 306, DE-AS 14 95 745, DE-OS 15 95 602, DE-OS 17 70 068,
DE-OS 20 19 324, DE-OS 20 35 732, DE-OS 24 46 440, DE-OS 23
45 256, DE-OS 24 27 274, US-PS 3,479,310 and Angewandte
6 5~ ~
Chemie 82, 53 (1970) and Angew. Makromol. Chem. 26, 85 et
seq (1972).
Of the processes mentioned, the "acetone process"
according to DE-OS 14 95 745 (= US-PS 3,479,310) and DE-OS
14 95 847 (GB-PS 1,067,788) is of particular importance.
In this process, an NCO-terminated prepolymer is generally
first prepared and then dissolved in an inert solvent,
followed by chain extension in solution to form the high
molecular weight polyurethane. The hydrophilic groups
required for dispersion are preferably introduced either by
the incorporation of diols bearing ionic and/or potentially
ionic and, optionally, nonionic hydrophilic groups into the
prepolymer or by the use of corresponding amines as chain-
extending agents. Dispersion takes place continuously in
tanks equipped with stirrers and, optionally, baffles. The
solvent used is generally distilled off from the stirred
tank immediately after dispersion in water.
Other processes for the production of polyurethane
prepolymers, more especially for the continuous production
of polyurethane prepolymers, are described in DE-OS 22 60
870, 23 11 635 and 23 44 135.
To obtain substantially clear, i.e. from water-clear
and transparent to translucent, polyurethane dispersions
according to the invention, it is important to maintain an
appropriate ratio between the component(s) capable of salt
formation and the other polyurethane-forming components.
Thus, it is preferred to use the component capable of salt
formation, when it is dimethylolpropionic acid, in
quantities of from 1 to 30~ by weight, more preferably in
quantities of from 2 to 20% by weight, and most preferably
in quantities of from 10 to 18% by weight, based on total
polyol reacted to form the urethane. In addition, the
transparency depends on the degree of neutralization. One
skilled in the art is able, through a few preliminary
tests, to determine what quantity of modifier capable of
ion formation and what quantity of neutralizing agent
produce an adequate degree of transparency. In general, as
~3396~
little of these components as possible to obtain the needed
degree of transparency will be used, because they can
adversely affect the water resistance of the adhesive film
if used in excessive quantities.
The polyurethane dispersions according to the inven-
tion are two-phase aqueous/polyurethane dispersions, pref-
erably comprising the polyurethane phase as a colloid or
sol, with a particle size of 10 to 100 nanometers. These
dispersions are preferably optically translucent to
transparent, and are to be distinguished from optically
clear "true" solutions.
The solids content of the adhesive solutions according
to the invention may be varied within wide limits. Solids
contents of from 20 to 70% by weight and preferably from 30
to 50% by weight have proved effective in practice.
The practice of the invention may be further
appreciated from the following operating examples and
comparison examples.
E x a m p 1 e s
General Synthesis Procedure
The polyols are dissolved or dispersed in acetone.
The component capable of ion formation is then added with
stirring. Diisocyanate is then added at temperatures of 50
to 70~ C until there is no further reduction in the NCO
content. The reaction mixture is then neutralized at 60~
C, for example with N-methyl morpholine. After about 30
minutes, water is added. After dispersion for 30 minutes,
the acetone is distilled off, ultimately under a fairly
high vacuum at temperatures of 55 to 60~ C.
The ingredients used in the Example according to the
invention and in Comparison Example 1 are shown in Table 1.
Some results of adhesion tests with these adhesives and two
other commercial types of household adhesives are shown in
Table 2.
1~39~56
Table 1
Ingredient Parts by Weiqht (pbw) Used in:
Example Comparison
ExamPle 1 -
Polytetrahydrofuran 100 pbw
Glycerol-started polyether - 100 pbw
polyol, OH value 34
Oleochemical polyol - 82 pbw
according to DE 37 04 350,
OH value 160
Dimethylolpropionic acid lS.58 pbw 21.50 pbw
Acetone 50 pbw 50 pbw
Isophorone diisocyanate 48.9 pbw 98.05 pbw
N-methyl morpholine 11.63 pbw 16.04 pbw
Deionized water 233 pbw 450 pbw
Table 2
Substrates Tensile Shear Strength in Newton-meters
Bonded Per Square Meter of Bonded Surface*
Example Comparison Universal PVAc
Example 1 adhesive, disper-
solvent- sion
based
Wood/PVC 6.0 1.4 n.d. 1.6
Wood/wood 8.5 4.5 6-7 3.0
Wood/alu 6.0 4.9 1.4 2.0
Wood/ABS 5.0 1.4 5.5 with 1.5
swelling of
the ABS
PVC = poly(vinyl chloride) plastic; alu = aluminum metal;
ABS = acrylonitrile-butadiene-styrene plastic; n.d. = not
determined; * indicates measured according to DIN 53 254.
.~3~65~
Test of Speed of Bond Formation
For this test, a 60 ~m thick adhesive film was applied
to chromo paper with a wire wound coating bar. Immediately
another piece of the same paper was pressed against the wet
adhesive film. The two pieces of paper were slowly rubbed
against one another until the development of an adhesive
bond caused one of the pieces of paper to tear. The time
to such tearing was found to be as shown in Table 3.
Table 3
Example Comparison Universal adhesive PVAc disper-
Example 1 solvent-based sion
15 secs. 20 secs. 70 secs. 25 secs.
Additional comparison examples were prepared in the
same general manner as indicated above for the
preparation of the Example and Comparison Example 1, but
using a polyester diol that is conventional for making
polyurethanes, rather than a polyether diol as required
for this invention, to be reacted to produce the
polyurethane used in these comparison examples.
Additional information about the diol used and the
amounts of various ingredients used to make the polymers
is shown in Table 4, as are the results of the adhesion
tests done with these products.
Storage Test
Polyurethane dispersions made according to the
Example and according to Comparison Example 1 to 4 were
subjected to a storage test at temperatures of 50~C. The
observed change in viscosity is shown in Table 5.
The results in Tables 4 and 5 show that with some of
the comparative Examples, notably Comparative Example 4,
one can initially obtain adhesive strengths about as good
as with the Examples according to the invention. The
Comparative Examples, however, have far less storage
stability. On the other hand, Comparison Example 1 has
13396.56
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Comparison Example 2 3.700 0.180
Comparison Example 3 3.500 0.120
Comparison Example 4 3.600 0.410
reasonably good storage stability but substantially poorer
adhesion for all the substrates shown in Table 2. Thus the
Example according to the present invention possesses a
unique combination of properties: the ability to bond
strongly a wide variety of materials, including paper,
wood, metal, and several plastics; no loss in viscosity
after three months storage; transparency; and freedom from
any significant amount of organic solvents, with their
associated nuisance of odor and hazard of fire.
