Note: Descriptions are shown in the official language in which they were submitted.
CA 022~3119 1998-11-09
Le A 32 640-US Eck/ng~/N l / v /~.u~
HYDROP~IT,17,1NG AGENT PRECURSOR, A PROCESS FOR ITS PREP-
ARATION AND ITS USE AS A DISPERSING AGENT FOR AQUEOUS
POLYURETHANE DISPERSION
FIELD OF THE INVENTION
The present invention relates to a new hydrophilizing agent and its preparation and
use, in particular as a dispersing agent in aqueous polyurethane dispersions.
BACKGROUND OF THE INVENTION
lû It is known that NCO prepolymers are hydrophilized by reaction with suitable
molecules with ionic groups, e.g., carboxylate anions. It is also known that poly-
urethanes hydrophilized in this way can be converted into polyurethane plastics
which can then be dispersed in water for the production of coatings for substrates
such as textiles, sheet metals, stone or wood. A review article by Rosthauser and
Nachtkamp in "Advances in Urethane Science and Technology", Volume lû, page
121 - 162 (1987) summarizes the knowledge in this field.
ACS Registry Number 8454û-26-1 discloses ~-AIanine, N-[(5-amino-1,3,3-
trimethylcyclohexyl)methyl]-,monopotassium salt. British Patent 1,339,357, (British
2û version of DE-A 2,û34,479), discloses dispersing agent building blocks made with
the alkali metal salt of the addition product of an a-olefinic carboxylic acid, i.e.,
acrylic acid, and an aliphatic diprimary diamine. Alkali metal salts used to make the
alkali metal salt of the addition product of an a-olefinic carboxylic acid and adiamine are prepared from the hydroxides, carbonates or bicarbonates of sodium,
potassium or lithium. The alkali metal salts are critical, and there is no suggestion
that the polyurethane lattices can be made without the alkali metal salt of the addition
product of an a-olefinic carboxylic acid and a diamine. There is no suggestion that
cyclic diamines, e.g., isophorone diisocyanate, can be used. The agents can be used
to make polyurethane lattices, which when dried, are intended to have little tendency
3û to swell in water and suitable resistance to water. To make the polyurethane lattices,
a prepolymer containing isocyanate group reacts with the alkali metal salt of the
LeA32640-US CA 022~3119 1998-11-09
addition product of an a-olefinic carboxylic acid and an aliphatic diamine.
These agents are disadvantageous because they are permanently hydrophilized (dueto the presence of the non-volatile base content, e.g., sodium), and do not have the
lower hydrophilicity that is desired in some applications. Correspondingly, the
coatings formed by the dispersing agents after being applied and stoving of a
polyurethane dispersion such that the textile coatings or the lacquers produced with
them still have an increased sensitivity to water. It would be desired to develop a
hydrophilizing agent sufficiently versatile so that it can have either temporary hydro-
philicity or permanent hydrophilicity. Another disadvantage of this group of
dispersing agents is the intense yellow-brown intrinsic color, which manifests itself
noticeably in a troublesome manner in pale-colored coatings.
The object of the invention is to overcome the disadvantages above, and therefore
provide a dispersing agent which on the one hand is colorless and on the other hand
can be temporarily hydrophilized or permanently hydrophilized. It is a further object
of the invention to develop a simple process for making the dispersing agent. This
object has been achieved with the discovery of the compound according to the
invention.
SUMMARY OF THE INVENTION
The invention relates to a hydrophilizing agent precursor prepared by the Michael
addition of 1-amino-3,3,5-trimethyl-5-aminomethyl-cyclohexane with an oc,~-
unsaturated carboxylic acid. The term "Michael Addition" is known and refers to the
overall addition to a"B-unsaturated carbonyl compounds in which an a,~-unsaturated
carbonyl compound undergoes a nucleophilic attack at the end of the double bond
further from the carbonyl group. The hydrophilizing agent precursor can be perma-
nently or temporarily neutralized to form a hydrophilizing agent, depending on the
desired application. The invention also relates to the use of the hydrophilizing agent
as a chain lengthener of NCO prepolymers for use in the preparation of an aqueous
polyurethane dispersion. The invention also relates to a hydrophilized polyurethane
coating on a substrate, e.g., leather and textiles.
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DETAILED DESCRIPTION OF THE INVENTION
The invention relates to a hydrophilizing agent precursor prepared by Michael
addition of 1-amino-3,3,5-trimethyl-5-aminomethyl-cyclohexane with an a,~-
unsaturated carboxylic acid. IPDA is a known compound which can be obtained
5 from commercial sources. The a,~-unsaturated carboxylic acids include but are not
limited to acrylic acid, methacrylic acid or crotonic acid and can also be obtained
commercially. Generally, the a"~-unsaturated carboxylic acid is used in an amount
ranging from 1 to 2 mol. Specific amounts are given in the examples below or canbe readily obtained with routine experimentation. The fact that an a"B-unsaturated
10 acid is reacted directly with IPDA and that this reaction product is a storage stable,
almost colorless compound is essential to the invention. This storage-stable
compound can be incorporated into NCO prepolymer chains and then neutralized.
Preferably, the invention relates to the Michael addition product of IPDA and acrylic
15 acid, in which a compound mixture of unreacted IPDA, mono-adduct and di-adduct
forms. The mono-adduct predominantly formed has the formula
NH2
~ CH--NH CH2--CH2 COOM
in which
M represents H, an alkali/alkaline earth metal, such as Na, K, "2Ca or "2Mg, or
an amine moiety. Suitable amine moieties include NH4+ and N(R)3, where R
is methyl, ethyl and/or hydroxyether.
25 The hydrophilizing agent precursor of the invention is neutralized permanently or
temporarily, depending on the needs of a specific application. Suitable neutralizing
agents for temporary hydrophilization include but are not limited to (i) volatile
tertiary amines, e.g., dimethyl ethanol amine or triethylamine, and (ii) diprimary
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Le A 32 640-US
amines which can be incorporated by isophoronediamine or 4,4' diamino-
dicyclohexylmethane, and the like. Suitable neutralizing agents for permanently
hydrophilization include metal bases, e.g., alkali/alkaline earth metal hydroxide.
Generally, the neutralizing agent is used in an amount up to the equivalent of the
5 COOH groups. Specific amounts of the neutralizing agent are given in the examples
below or can be readily obtained with routine experimentation.
The hydrophilizing agent precursor according to the invention can be used in anyway to meet the objects of the invention. The hydrophili7.ing agent precursors
10 according to the invention, for instance, can be prepared by first introducing 1 mol of
IPDA into a reaction vessel, preferably in water or isopropanol. ~,~-unsaturated car-
boxylic acid, e.g., acrylic acid, can then be added dropwise into the reaction vessel at
room temperature with stirring. The reaction manifests itself by a slight
exothermicity. After the addition of the acid, the mixture is subsequently stirred at
15 40~C for 1 hour, and a clear colorless solution results. The clear and colorless
solution of the hydrophilizing agent can then be suitably employed. For example, the
solution can be added in a suitable amount to an acetonic NCO prepolymer solution
at approx. 40~C, so that the hydrophilizing agent becomes incorporated into the
polyurethane chains. Neutralization is then carried out with the calculated amount of
20 base. It can then be decided whether a permanent hydrophilization, that is to say a
neutralization with non-volatile metal hydroxides, or only a temporary
hydrophilization, e.g., without an alkali metal. That is to say a neutralization with
amines, is desired. An acetonic polyurethane solution can be dispersed in water in
accordance with known techniques and further processed into an aqueous
25 polyurethane dispersion for coatings by removal of the acetone by distillation. The
preparation method generally does not utilize acyclic diamines. Specific amountscan be obtained by routine experimentation. Coatings can be made by applying thedispersion over a suitable substrate and drying the dispersion at a suitable
temperature, e.g., 80~C.
The resulting film (coating) has properties which are suitable for substrates such as
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textile materials, paper, plastics, metals, and glass. Film properties can be
characterized by determining the film's modulus, tensile dry strength, elongation at
break dry, tensile wet strength, elongation at break wet, and the like. Example S
below shows film properties of a coating prepared in accordance to the invention.
5 Properties of other coatings can be determined by routine experimentation.
As already mentioned in part, the hydrophilizing agents according to the invention
have the following advantageous properties:
- easy preparation
10 - no yellow coloration, and instead colorlessness
- possibility of choice of salt formation with non-volatile bases (metal
hydroxides) or with volatile bases (amines)
- good compatibility with NCO prepolymers
- extension of the range of carboxylate-containing dispersing agents available.
The last two points are explained as follows. Carboxylate-containing hydrophiIizing
agents have a weaker permanent hydrophilicity than sulfonate-containing
hydrophilizing agents, and for this reason the former are also preferred for aqueous
lacquer applications or textile coatings with a high level of properties. However,
20 only few such hydrophilization building blocks exist on the market, such as
carboxylate-containing compounds of dimethylolpropionic acid.
The hydrophilizing agents according to the invention supplement the range available
in this respect and extend the possibilities of combinations of chemicals, because the
25 new hydrophilizing components are based on the IPDA hard segment, which is
known to have a good compatibility. They are therefore particularly suitable forcoating surfaces of the most diverse working substances and materials, e.g., textile
materials, paper, plastics, metals, glass, etc., can be coated with them.
30 The invention is further described in the following illustrative examples. All parts
are by weight unless otherwise indicated.
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EXAMPLES
Example 1
Batch:
85.0 g (1 eq NH2)* isophoronediamine
36.0 g (0.5 mol) acrylic acid
282.0 g water
403.0 g (1 eq NH/NH2) dispersing agent solution
solids: calc. 30%
1 acid equivalent: 806 g
* based on the C=C double bond
Procedure:
IPDA and water were initially introduced into the reaction vessel at room
5 temperature. Acrylic acid was added dropwise to this mixture, while stirring, the
mixture warming slightly. When the addition of the acrylic acid has ended, the
mixture was subsequently stirred at 45~C for 1 hour. A clear, colorless dispersing
agent solution (30%) with an NH/NH2 equivalent weight of 403 g and an acid
equivalent of 806 g was obtained.
This dispersing agent solution can also easily be prepared in concentrated form, for
example 50 or 60%. However, there was then the risk of crystallizing out at roomtemperature. Nevertheless, if these high-solids variants were stored at 60 to 70~C,
they also remain liquid.
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Example 2 (use example)
Batch:
235.0 g (0 236 eq) of a polycarbonate based on hexane-1,6-
diol of OH number 56
80.0 g (0.080 eq) of a polytetramethylene glycol of OH
number 56
10.0 g (0.020 eq) of a monofunctional ethylene oxide
polyether of molecular weight 500
4.3 g (0.064 eq) dimethylpropionic acid
33.6 g (0.400 eq) 1,6-diisocyanatohexane (HDI)
35.6 g (0.320 eq) 1 -isocyanato-3,3,5-trimethyl-5-isocyanato-
methyl-cyclohexane (IPDI)
28.2 g (0.070 eq) dispersing agent according to
Example 1
7.65 g (0.090 eq) 1-amino-3,3,5-trimethyl-5-aminomethyl-
cyclohexane (IPDA)
8.08 g (0.08 eq) triethylamine
612.0 g water
1,055.43 g dispersion (40%)
viscosity (23~C) approx. 900 mPa s
Procedure:
The above polyols were dewatered at 100~C under 40 mbar for 30 min. and cooled to
approx. 90~C. The two diisocyanates were added all at once, while stirring, and the
reaction was carried out at 90~C for approx. 2 hours. An NCO content of 3.2% wasmeasured, the calculated content being 3.36%. The mixture was diluted with 400 gacetone and a mixture of aqueous dispersing agent solution, IPDA and triethylamine
was added to the acetonic NCO prepolymer solution, which has been heated to
approx. 45~C. Thereafter, the mixture was subsequently stirred at 45~C for approx.
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Le A 32 640-US
another 1 hour and dispersed with water. After the acetone has been distilled off
(45~C/100 mbar), a milky-blue dispersion with a solids content of approx. 40% and a
viscosity (23~C) of approx. 900 mPa-s was obtained.
5 As a leather coating, the dispersion has suitable fastnesses to creasing, in particular
cold creasing (over 10,000 at -10~C and -30~C).
Example 3
lO This example describes the preparation of the hydrophilizing agent in an organic
solvent.
Batch:
170.0 g (2.0 eq) isophoronediamine
72.0 g (l.0 mol) acrylic acid
358.0 g isopropanol
600.0 g (2.0 eq NH/NH2) dispersing agent solution
solids: calc. approx. 40%
l acid equivalent: calc. 600 g
l 5 Procedure:
Isophoronediamine and isopropanol were initially introduced into the reaction vessel
and heated up to 40~C. Acrylic acid was added dropwise to this mixture, while
stirring, a slight exothermicity being observed. After the addition of the acrylic acid,
20 the mixture was subsequently stirred at 45~C for 2 hours. A ready-to-use colorless
dispersing agent solution with an NH/NH2 equivalent of 300 g and an acid equivalent
of 600 g was obtained
.
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Example 4 (according to the invention)
In contrast to Example 1, there is a 10% neutralization of the carboxyl groups with
KOH here.
Batch:
85.0 g (1 eqNH2) isophoronediamine
36.0 g (0.5 mol) acrylic acid
282.2g water
2.8 g (0.05 mol) potassium hydroxide
406.0 g (1.0 eq NH/NH2) dispersing agent solution
solids: calc. approx. 30.1%
1 acid equivalent: 902 g
Procedure:
10 The procedure was as described in Example 1, and when the reaction has ended, the
stated amount of solid potassium hydroxide was also stirred in. A clear, colorless
dispersing agent solution (approx. 30%) which already contains permanent salt
groups to the extent of 10 equivalent % and also 90 equivalent % non-neutralizedcarboxyl groups was obtained. The equivalent weight, based on the NH or NH2
groups was 406 g.
Example 5 (use example)
In this example, neutralization of the dispersing agent was carried out to the extent of
20 30 equivalent % with 4,4'-diamino-dicyclohexyl-methane, which was incorporated
during curing (heat) of the coating. Consequently, a permanent hydrophilization of
only 10 equivalent % on the part of the KOH exists in the cured coating.
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Batch:
49.5 g (0.022 eq) of a monofunctional ethylene
oxide/propylene oxide polyether of OH
number 25
80.0 g (0.080 eq) of a polypropylene glycol of OH number
56
110.0 g (0.110 eq) of a polycarbonate based on 1,6-
dihydroxyhexane of OH number 56
110.0 g (0.110 eq) of a propylene oxide polyether started on
trimethylolpropane of OH number 56
76.5 g (0.612 g) 4,4'-diisocyanato-diphenylmethane
12.18 g (0.14 eq) butanone oxime
60.90 g (0.15 eq) dispersing agent according to
Example 4
14.70 g (0.14 eq) 4,4'-diamino-dicyclohexylmethane
533 57 water
1047.35 g dispersion
solids: 45%
viscosity (23~C): approx. 500 mPa s
Procedure:
5 The above polyols were dewatered at 100~C under 20 mbar and cooled to approx.
60~C. Thereafter, the total amount of polyurethane MDI was added all at once, while
stirring, the mixture was heated slowly to 70~C and the reaction was carried out at
this temperature for approx. 3 hours, until the NCO content has fallen to approx.
2.75%, an NCO content of 2.86% being calculated. The mixture was diluted with
500 g acetone and brought to approx. 40~C, and another control NCO measurement
was carried out. An NCO content of approx. 1.2% was found, the calculated content
being 1.3%. Thereafter, butanone oxime was added, the mixture was stirred at 40~C
for approx. 20 min and an NCO content of approx. 0.58% was determined, the
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calculated content being 0.67%. The dispersing agent solution according to Example
4 was then added and the mixture was subsequently stirred at 40~C for approx. 30min, until no further NCO content was detectable. The diamine was now stirred in,
and after approx. 15 min. the mixture was dispersed with water. After the acetone
5 has been distilled off (45~C/100 mbar), a milky-blue dispersion with a solids content
of 45% and a viscosity at 23~C of approx. 500 mPa s was obtained. In spite of the
potentially reactive character, the dispersion was stable on storage.
Properties of the coating from the above dispersion
10 The dispersion was processed to a film or a gluing layer between PVC and
polyamide according to a particular drying program (approx. I min. 80~C, approx. 1
min. 120~C and approx. 1 min. 140~C).
Film properties:
100% modulus 2.3 MPa
Tensile strength dry 11.0 MPa
Elongation at break dry 490%
Tensile strength wet 8.8 MPa
Elongation at break wet 510%
Swelling vol. EE 502%
Swelling vol. H2O 33%
Film weight 70 g/m2
Adhesive strength on polyamide:
dry (N/2.5 cm) 34
wet (N/2.5 cm) 18
Although the invention has been described in detail in the foregoing for the purpose of
illustration, it is to be understood that such detail is solely for that purpose and that
variations can be made therein by those skilled in the art without departing from the
spirit and scope of the invention.
