U.S. patent application number 10/761643 was filed with the patent office on 2005-07-21 for process for preparing aspartates.
Invention is credited to Danielmeier, Karsten, Gambino, Charles A., Gertzmann, Rolf, Henderson, Karen M., Roesler, Richard R., Squiller, Edward P., Vargo, Michele E., Wayt, Terrell D..
Application Number | 20050159560 10/761643 |
Document ID | / |
Family ID | 34679324 |
Filed Date | 2005-07-21 |
United States Patent
Application |
20050159560 |
Kind Code |
A1 |
Danielmeier, Karsten ; et
al. |
July 21, 2005 |
PROCESS FOR PREPARING ASPARTATES
Abstract
The present invention relates to novel aspartates, their method
of production and the use of these aspartates as reactive
components for polyisocyanates in two-component polyurethane
coating compositions and for preparing polyurethane prepolymers.
The aspartates are prepared by first reacting a di- or polyamine
with an unsaturated ester and then reacting the resultant product
with a maleimide.
Inventors: |
Danielmeier, Karsten;
(Sollingen-Burg, DE) ; Gambino, Charles A.;
(McDonald, PA) ; Gertzmann, Rolf; (Leverkusen,
DE) ; Roesler, Richard R.; (Wexford, PA) ;
Wayt, Terrell D.; (Moundsville, WV) ; Vargo, Michele
E.; (Pittsburgh, PA) ; Squiller, Edward P.;
(Bridgeville, PA) ; Henderson, Karen M.;
(Coraopolis, PA) |
Correspondence
Address: |
BAYER MATERIAL SCIENCE LLC
100 BAYER ROAD
PITTSBURGH
PA
15205
US
|
Family ID: |
34679324 |
Appl. No.: |
10/761643 |
Filed: |
January 21, 2004 |
Current U.S.
Class: |
525/422 ;
528/335; 528/422 |
Current CPC
Class: |
C07D 207/416 20130101;
C09D 175/04 20130101; C08G 18/3821 20130101; C08G 18/792
20130101 |
Class at
Publication: |
525/422 ;
528/422; 528/335 |
International
Class: |
C08G 063/02; C08G
069/26 |
Claims
What is claimed is:
1. An aspartate of the formula: 3where x represents an m-valent
organic residue obtained by removing the primary amino group or
groups from a di- or polyamine containing primary amino groups and
having a number average molecular weight of 60 to 6000, and which
may contain further functional groups that either are reactive with
isocyanate groups or are inert to isocyanate groups at temperatures
of up to 100.degree. C., R.sub.3 and R.sub.4 may be identical or
different and represent hydrogen or organic groups which are inert
towards isocyanate groups at a temperature of 100.degree. C. or
less, R.sub.1 and R.sub.2 may be identical or different and
represent organic groups which are inert towards isocyanate groups
at a temperature of 100.degree. C. or less, R.sub.5 and R.sub.6 may
be the same or different and represent moieties selected from the
group consisting of i) hydrogen, ii) straight or branched C.sub.1
to C.sub.8 alkyl groups, which may be substituted with up to three
aryl groups containing from 6 to 10 carbon atoms, iii) C.sub.6 to
C.sub.10 aryl groups, which may be substituted with up to three
alkyl groups having from 1 to 3 carbon atoms, and iv) together form
a six-membered cycloalkyl group, with said cycloalkyl group being
substituted with from 0 to 3 alkyl groups having from 1 to 3 carbon
atoms, R.sub.7 represents a moiety selected from the group
consisting of i) hydrogen, ii) straight or branched C.sub.1 to
C.sub.8 alkyl groups, which may be substituted with up to three
aryl groups containing from 6 to 10 carbon atoms, and iii) C.sub.6
to C.sub.10 aryl groups, which may be substituted with up to three
alkyl groups having from 1 to 3 carbon atoms, a and b represent
integers of from 1 to 5, provided that the sum of a and b is from 2
to 6.
2. The aspartate of claim 1, wherein X represents a divalent
hydrocarbon group obtained by removing the amino groups from
1-amino-3-aminomethyl-3,- 5,5-trimethyl-cyclohexane (isophorone
diamine or IPDA), bis-(4-aminocyclohexyl)-methane,
bis-(4-amino-3-methylcyclohexyl)-methane- , 1,6-diamino-hexane,
2-methyl pentamethylene diamine, ethylene diamine or
3,3'-[1,2-ethanediylbis(oxy)]bis (1-propaneamine).
3. The aspartate of claim 1, wherein R.sub.3 and R.sub.4 are
hydrogen.
4. The aspartate of claim 1, wherein R.sub.1 and R.sub.2 are each
alkyl groups having from 1 to 8 carbon atoms.
5. A process for preparing an aspartate of the formula: 4where x
represents an m-valent organic residue obtained by removing the
primary amino group or groups from a di- or polyamine containing
primary amino groups and having a number average molecular weight
of 60 to 6000, and which may contain further functional groups that
either are reactive with isocyanate groups or are inert to
isocyanate groups at temperatures of up to 100.degree. C., R.sub.3
and R.sub.4 may be identical or different and represent hydrogen or
organic groups which are inert towards isocyanate groups at a
temperature of 100.degree. C. or less, R.sub.1 and R.sub.2 may be
identical or different and represent organic groups which are inert
towards isocyanate groups at a temperature of 100.degree. C. or
less, R.sub.5 and R.sub.6 may be the same or different and
represent moieties selected from the group consisting of i)
hydrogen, ii) straight or branched C.sub.1 to C.sub.8 alkyl groups,
which may be substituted with up to three aryl groups containing
from 6 to 10 carbon atoms, iii) C.sub.6 to C.sub.10 aryl groups,
which may be substituted with up to three alkyl groups having from
1 to 3 carbon atoms, and iv) together form a six-membered
cycloalkyl group, with said cycloalkyl group being substituted with
from 0 to 3 alkyl groups having from 1 to 3 carbon atoms, R.sub.7
represents a moiety selected from the group consisting of i)
hydrogen, ii) straight or branched C.sub.1 to C.sub.8 alkyl groups,
which may be substituted with up to three aryl groups containing
from 6 to 10 carbon atoms, and iii) C.sub.6 to C.sub.10 aryl
groups, which may be substituted with up to three alkyl groups
having from 1 to 3 carbon atoms, a and b represent integers of from
1 to 5, provided that the sum of a and b is from 2 to 6, comprising
A) reacting at a temperature of 0 to 100.degree. C., in solution or
in the absence of a solvent and at an equivalent ratio of primary
amino groups in component a) to C.dbd.C double bonds in component
b) of from about 1.1:1 to about 3.0:1 a) di- or polyamines
corresponding to formula (II) X[--NH.sub.2].sub.m (II) with b)
compounds corresponding to formula (III)
R.sub.3OOC--C(R.sub.5).dbd.C(- R.sub.6)--COOR.sub.4 (III) wherein
X, R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are as defined above and m
represents an integer of from 2 to 6, and B) reacting the resultant
product with a maleimide.
6. The process of claim 5, wherein X represents a divalent
hydrocarbon group obtained by removing the amino groups from
1-amino-3-aminomethyl-3,- 5,5-trimethyl-cyclohexane (isophorone
diamine or IPDA), bis-(4-aminocyclohexyl)-methane,
bis-(4-amino-3-methylcyclohexyl)-methane- , 1,6-diamino-hexane,
2-methyl pentamethylene diamine, ethylene diamine or
3,3'-[1,2-ethanediylbis(oxy)]bis (1-propaneamine).
7. The process of claim 5, wherein R.sub.3 and R.sub.4 are
hydrogen.
8. The process of claim 5, wherein R.sub.1 and R.sub.2 are each
alkyl groups having from 1 to 8 carbon atoms.
9. The process of claim 5, wherein said maleimide is of the
formula: 5where R.sub.5, R.sub.6 and R.sub.7 are as defined
above.
10. A two-component coating composition which comprises, as binder,
a) a polyisocyanate component and b) an isocyanate-reactive
component containing b1) the aspartate of claim 1, b2) optionally
other isocyanate-reactive compounds, wherein the equivalent ratio
of isocyanate groups to isocyanate-reactive groups is from about
0.8:1 to about 2.0:1.
11. A prepolymer containing urea, urethane, allophanate and/or
biuret structures comprising the reaction product of a
polyisocyanate with the aspartate of claim 1.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to novel aspartates, a process
for preparing them from primary amines and maleates and to their
use as reactive components for polyisocyanates in two-component
polyurethane coating compositions and for preparing polyurethane
prepolymers.
[0002] Two-component coating compositions which contain, as binder,
a polyisocyanate component combined with one or more
isocyanate-reactive components are known. They are suitable for
preparing high quality coatings which are hard, elastic, abrasion
resistant, solvent resistant and weather resistant.
[0003] Secondary polyamines which contain ester groups have become
established in the two-component surface coating industry. They are
particularly suitable, in combination with lacquer polyisocyanates,
as binders in low-solvent or solvent-free, high solids coating
compositions because they provide rapid curing of the coatings at
low temperatures.
[0004] These secondary polyamines are polyaspartates and are
described, e.g., in U.S. Pat. Nos. 5,126,170, 5,214,086, 5,236,741,
5,243,012, 5,364,955, 5,412,056, 5,623,045, 5,736,604, 6,183,870,
6,355,829, 6,458,293 and 6,482,333 and published European Patent
Application 667,362. In addition, aspartates containing aldimine
groups are also known (see U.S. Pat. Nos. 5,489,704, 5,559,204 and
5,847,195). Secondary aspartic acid amide esters are also known
(see U.S. Pat. No. 6,005,062). Their use as the only
isocyanate-reactive component or mixed with other
isocyanate-reactive components in two-component coating
compositions are also described in the above-identified
patents.
[0005] The process for preparing these polyaspartates is the
reaction of the corresponding primary polyamines with maleates or
fumarates corresponding to the formula
R.sub.1OOC--C(R.sub.3).dbd.C(R.sub.4)--COOR.sub.2
[0006] wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are identical
or different organic groups, resulting in the formation of
secondary polyamines. Due to stearic, structural and electronic
effects, these secondary amino groups have sufficiently reduced
reactivity towards isocyanate groups to be mixable with
polyisocyanates in a reliable and easy manner.
[0007] The reaction which is used to prepare polyaspartates is the
addition of primary amines to the activated C--C double bond in
vinyl carbonyl compounds, which has been described in the
literature (see Chem. Ber. 1946, 38, 83; Houben Weyl, Meth. d. Org.
Chemie, Vol. 11/1, 272 (1957); Usp. Chimii 1969, 38,1933). It has
been found, however, that this reaction does not proceed to
completion during the course of the actual synthesis process (e.g.,
24 hours with stirring at 60.degree. C.). The actual extent of the
reaction is dependent upon the type of primary polyamine. Thus, the
degree of conversion (measured by the concentration of free,
unconverted maleate and fumarate, into which maleate rearranges in
the presence of basic catalysts) after 1 day with 1,6-hexanediamine
is about 90 to 93%. The degree of conversion after 1 day with a
cycloaliphatic polyamine having sterically hindered primary amino
groups, i.e., 4,4'-diamino-3,3'-dimethyldicyclohexylmethane is only
77%. Complete or essentially complete conversion is achieved only
after several days or, in the case of
4,4'-diamino-3,3'-dimethyldicyclohexyl-methane, only after several
months.
[0008] In a typical commercial production, the reaction is run for
sixteen hours when the conversion is somewhere between 75 and 95%
complete depending on the amine used. The "unfinished" material is
drummed and held in storage until the reaction is complete. This
typically takes anywhere from two weeks to six months. U.S. Pat.
No. 5,821,326 describes the use of certain five-membered aromatic
ring compounds as catalyst to accelerate the preparation of the
aspartates.
[0009] The conventional aspartates are capable of a further
transformation (after curing with an isocyanate) to form a
hydantoin ring structure. This hydantoin formation might lead to a
shrinking of the coating and undesired alcohol formation. It would
also be desirable to prepare an aspartate that would be less prone
to hydantoin formation.
DESCRIPTION OF THE INVENTION
[0010] The present invention is directed to novel aspartates of the
formula: 1
[0011] where
[0012] X represents an m-valent organic residue obtained by
removing the primary amino group or groups from a di- or polyamine
containing primary amino groups and having a number average
molecular weight of 60 to 6000, and which may contain further
functional groups that either are reactive with isocyanate groups
or are inert to isocyanate groups at temperatures of up to
100.degree. C.,
[0013] R.sub.3 and R.sub.4 may be identical or different and
represent hydrogen or organic groups which are inert towards
isocyanate groups at a temperature of 100.degree. C. or less (both
are preferably hydrogen),
[0014] R.sub.1 and R.sub.2 may be identical or different and
represent organic groups which are inert towards isocyanate groups
at a temperature of 100.degree. C. or less (preferably a C.sub.1 to
C.sub.8 alkyl and most preferably methyl or ethyl),
[0015] R.sub.5 and R.sub.6 may be the same or different and
represent moieties selected from the group consisting of i)
hydrogen, ii) straight or branched C.sub.1 to C.sub.8 alkyl groups,
which may be substituted with up to three aryl groups containing
from 6 to 10 carbon atoms, iii) C.sub.6 to C.sub.10 aryl groups,
which may be substituted with up to three alkyl groups having from
1 to 3 carbon atoms, and iv) together form a six-membered
cycloalkyl group, with said cycloalkyl group being substituted with
from 0 to 3 alkyl groups having from 1 to 3 carbon atoms,
[0016] R.sub.7 represents a moiety selected from the group
consisting of i) hydrogen, ii) straight or branched C.sub.1 to
C.sub.8 alkyl groups, which may be substituted with up to three
aryl groups containing from 6 to 10 carbon atoms, and iii) C.sub.6
to C.sub.10 aryl groups, which may be substituted with up to three
alkyl groups having from 1 to 3 carbon atoms,
[0017] a and b represent integers of from 1 to 5, provided that the
sum of a and b is from 2 to 6.
[0018] The products of the present invention, when combined with a
polyisocyanate, have longer potlifes and provide for harder
coatings than aspartates of the prior art. In addition, the
products have less of a tendency to form hydantoin rings.
[0019] The present invention also relates to a process for
preparing aspartates of the above formula comprising
[0020] A) reacting at a temperature of 0 to 100.degree. C., in
solution or in the absence of a solvent and at an equivalent ratio
of primary amino groups in component a) to C.dbd.C double bonds in
component b) of from about 1.1:1 to about 3.0:1
[0021] a) di- or polyamines corresponding to formula (II)
X[--NH.sub.2].sub.m (II)
[0022] with
[0023] b) compounds corresponding to formula (III)
R.sub.1OOC--C(R.sub.3).dbd.C(R.sub.4)--COOR.sub.2 (III)
[0024] wherein
[0025] X, R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are as defined
above and
[0026] m represents an integer of from 2 to 6, and
[0027] B) reacting the resultant product with a maleimide.
[0028] The present invention also relates to a two-component
coating composition which contains, as binder,
[0029] a) a polyisocyanate component and
[0030] b) an isocyanate-reactive component containing
[0031] b1) a compound corresponding to formula (I) and
[0032] b2) optionally other isocyanate-reactive compounds,
[0033] wherein the equivalent ratio of isocyanate groups to
isocyanate-reactive groups is from about 0.8:1 to about 2:1, and
optionally, additives known in surface coatings technology.
[0034] Finally, the present invention also relates to prepolymers
containing urea, urethane, allophanate and/or biuret structures,
which are based on the reaction product of polyisocyanates with the
aspartates of the invention, optionally in admixture with one or
more isocyanate-reactive components.
[0035] The polyamines useful herein include i) high molecular
weight amines having molecular weights of 400 to about 10,000,
preferably 800 to about 6,000, and ii) low molecular weight amines
having molecular weights below 400. The molecular weights are
number average molecular weights (M.sub.n) and are determined by
end group analysis (NH number). Examples of these polyamines are
those wherein the amino groups are attached to aliphatic,
cycloaliphatic, araliphatic and/or aromatic carbon atoms.
[0036] Suitable low molecular polyamine starting compounds include
ethylene diamine, 1,2- and 1,3-propane diamine,
2-methyl-1,2-propane diamine, 2,2-dimethyl-1,3-propane diamine,
1,3- and 1,4-butane diamine, 1,3- and 1,5-pentane diamine,
2-methyl-1,5-pentane diamine, 1,6-hexane diamine,
2,5-dimethyl-2,5-hexane diamine, 2,2,4- and/or
2,4,4-trimethyl-1,6-hexane diamine, 1,7-heptane diamine, 1,8-octane
diamine, 1,9-nonane diamine, 1,10-decane diamine, 1,11-undecane
diamine, 1,12-dodecane diamine,
1-amino-3-aminomethyl-3,5,5-trimethyl cyclohexane, 2,4- and/or
2,6-hexahydrotoluylene diamine, 2,4'- and/or
4,4'-diamino-dicyclohexylmethane,
3,3'-dialkyl-4,4'-diamino-dicyclohexyl methanes (such as
3,3'-dimethyl-4,4'-diamino-dicyclohexyl methane and
3,3'-diethyl-4,4'-diamino-dicyclohexyl methane), 1,3- and/or
1,4-cyclohexane diamine, 1,3-bis(methylamino)-cyclohexane,
1,8-p-menthane diamine, hydrazine, hydrazides of semicarbazido
carboxylic acids, bis-hydrazides, bis-semicarbazides, phenylene
diamine, 2,4- and 2,6-toluylene diamine, 2,3- and 3,4-toluylene
diamine, 2,4'- and/or 4,4'-diaminodiphenyl methane, higher
functional polyphenylene polymethylene polyamines obtained by the
aniline/formaldehyde condensation reaction,
N,N,N-tris-(2-amino-ethyl)-amine, guanidine, melamine,
N-(2-aminoethyl)-1,3-propane diamine, 3,3'-diamino-benzidine,
polyoxypropylene amines, polyoxyethylene amines, mixed propylene
oxide/ethylene oxide diamines (such as
3,3'-[1,2-ethanediylbis(oxy)]bis (1-propaneamine)),
2,4-bis-(4'-aminobenzyl)-aniline and mixtures thereof.
[0037] Preferred polyamines are
1-amino-3-aminomethyl-3,5,5-trimethylcyclo- hexane (isophorone
diamine or IPDA), bis-(4-aminocyclohexyl)-methane,
bis-(4-amino-3-methylcyclohexyl)-methane, 1,6-diamino-hexane,
2-methyl pentamethylene diamine, ethylene diamine and
3,3'-[1,2-ethanediylbis(oxy)- ]bis (1-propaneamine).
[0038] Suitable high molecular weight polyamines correspond to the
polyhydroxyl compounds used to prepare the NCO prepolymers with the
exception that the terminal hydroxy groups are converted to amino
groups, either by amination or by reacting the hydroxy groups with
a diisocyanate and subsequently hydrolyzing the terminal isocyanate
group to an amino group. Preferred high molecular weight polyamines
are amine-terminated polyethers such as the Jeffamine resins
available from Huntsman.
[0039] Suitable optionally substituted maleic or fumaric acid
esters for use in the preparation of the aspartates are those
corresponding to the formula
R.sub.1OOC--C(R.sub.3).dbd.C(R.sub.4)--COOR.sub.2
[0040] wherein R.sub.3, R.sub.4, R.sub.5 and R.sub.6 are as
previously defined. Examples include the dimethyl, diethyl,
di-n-butyl and mixed alkyl esters of maleic acid and fumaric acid
and the corresponding maleic or fumaric acid esters substituted by
methyl in the 2- and/or 3-position. Suitable maleates or fumarates
for preparing the aspartates of the present invention include
dimethyl, diethyl, di-n-propyl, di-isopropyl, di-n-butyl and
di-2-ethylhexyl maleates, methylethylmaleate or the corresponding
fumarates.
[0041] The aspartates of the present invention are prepared by
first reacting component Aa) with component Ab) at temperatures of
0 and 100.degree. C., preferably 20 to 80.degree. C. and more
preferably 20 to 60.degree. C. wherein (i) the equivalent ratio of
primary amino groups in component a) to C.dbd.C double bond
equivalents in component b) is from about 1.1:1 to about 3.0:1,
preferably from about 1.1:1 to about 2.0:1. The reaction time may
vary from about 1 to about 4 hours, depending upon the type of
polyamine and the desired maximum residual concentration of
reactants in the reaction mixture. The resultant product is then
reacted with a maleimide.
[0042] Useful maleimides are those of the structure: 2
[0043] where R.sub.5, R.sub.6, and R.sub.7 are as defined above.
Specifically useful maleimides include N-methyl maleimide, N-ethyl
maleimide, N-propyl maleimide, N-isopropyl maleimide, N-isobutyl
maleimide, N-butyl maleimide, N-amyl maleimide, N-ethylamyl
maleimide, N-methylisoamyl maleimide, N-methylhexyl maleimide,
N-phenyl maleimide, N-ethyl-2-methylmaleimide, N-2,3-trimethyl
maleimide, 3-methyl-N-phenyl maleimide,
N-phenyl-3,4,5,6-tetrahydrophthalimide and 3-phenyl-N-phenyl
maleimide.
[0044] This second reaction is typically conducted at a temperature
of from about 50 to about 100.degree. C., for times ranging from
about 1 to about 4 hours. The ratio of reactants is chosen so that
at least one mole of maleimide is present for each unreacted amine
group. The excess maleimide can then be removed to give a 100%
resinous product, or it can remain and can serve as a solvent.
[0045] The process to prepare the aspartates of the present
invention may either be performed in solution or in the absence of
a solvent. Solvent may also be added after the synthesis process,
for example, to lower the viscosity. Suitable solvents include any
organic solvents, preferably those known from surface coating
technology. Examples include acetone, methyl ethyl ketone, methyl
isobutyl ketone, n-butyl acetate, methoxypropyl acetate, toluene,
xylene and higher aromatic solvents (such as the Solvesso solvents
from Exxon).
[0046] The aspartates prepared according to the invention may be
directly used as reactive components for polyisocyanates after
concluding the synthesis process.
[0047] One use of the aspartates of the present invention is to
prepare coatings from two-component coating compositions
containing, as binder,
[0048] a) a polyisocyanate component and
[0049] b) an isocyanate-reactive component containing
[0050] b1) the aspartates of the invention and
[0051] b2) optionally other known isocyanate-reactive
components.
[0052] Suitable polyisocyanate components a) are known and include
the polyisocyanates known from polyurethane chemistry, e.g., low
molecular weight polyisocyanates and lacquer polyisocyanates
prepared from these low molecular weight polyisocyanates. Preferred
are the lacquer polyisocyanates, which are known from surface
coating technology. These lacquer polyisocyanates contain biuret
groups, isocyanurate groups, allophanate groups, uretdione groups,
carbodiimide groups and/or urethane groups and are preferably
prepared from (cyclo)aliphatic polyisocyanates.
[0053] Suitable low molecular weight polyisocyanates for use in
accordance with the present invention or for preparing the lacquer
polyisocyanates are those having a molecular weight of 140 to 300,
such as 1,4-tetramethylene diisocyanate, 1,6-hexamethylene
diisocyanate (HDI), 2,2,4- and/or 2,4,4-trimethyl-hexamethylene
diisocyanate, dodecamethylene diisocyanate,
2-methyl-1,5-diisocyanatopentane, 1,4-diisocyanatocyclohexa- ne,
1-isocyanato-3,3,5-trimethyl-5-isocyanato-methylcyclohexane (IPDI),
2,4- and/or 4,4' diisocyanato-dicyclohexyl-methane,
1-isocyanato-1-methyl-3(4)-isocyanatomethyl-cyclohexane (IMCI),
2,4- and/or 2,6-hexahydrotoluylene diisocyanate (H.sub.6TDI), 2,4-
and/or 4,4'-diisocyanatodiphenylmethane or mixtures of these
isomers with their higher homologs (which may be obtained in known
manner by the phosgenation of aniline/formaldehyde condensates),
2,4- and/or 2,6-diisocyanatotoluene, and mixtures thereof. The use
of low molecular weight polyisocyanates themselves is not
preferred. Also, lacquer polyisocyanates prepared from aromatic
polyisocyanates, such as 2,4- and/or 2,6-diisocyanatotoluene, are
also less preferred. The lacquer polyisocyanates containing
urethane groups are preferably based on low molecular weight
polyhydroxyl compounds having molecular weights of 62 to 300, such
as ethylene glycol, propylene glycol and/or trimethylolpropane.
[0054] Preferred lacquer polyisocyanates for use as component a)
are those based on 1,6-hexamethylene diisocyanate and having an NCO
content of 16 to 24 wt. % and a maximum viscosity at 23.degree. C.
of 10,000, preferably 3,000 mPa.multidot.s.
[0055] Component b1) is selected from the aspartates of the present
invention. Preferably, X represents a divalent hydrocarbon group
obtained by removing the amino groups from
1-amino-3-aminomethyl-3,5,5-trimethyl-c- yclohexane (isophorone
diamine or IPDA), bis-(4-aminocyclohexyl)-methane,
bis-(4-amino-3-methylcyclohexyl)-methane, 1,6-diaminohexane,
2-methyl pentamethylene diamine, ethylene diamine and
3,3'-[1,2-ethanediylbis(oxy)- ]bis (1-propaneamine).
[0056] Particularly preferred starting components b1) include those
aspartates in which R.sub.1 and R.sub.2 represent C.sub.1 to
C.sub.8 alkyl groups such as methyl, ethyl, n-propyl, isopropyl,
n-butyl or 2-ethylhexyl.
[0057] Optional starting components b2) are known compounds
containing at least two isocyanate-reactive groups, including
groups which react with isocyanate groups under the effect of
either moisture or/and heat. Examples include hydroxy-functional
polyacrylates and polyesterpolyols Mixtures of these compounds may
also be used.
[0058] In the binders used according to the invention, the amounts
of components a), b1) and (optionally) b2) are selected such that
the equivalent ratio isocyanate groups to isocyanate-reactive
groups is from about 0.8:1 to about 2.0:1, and preferably from
about 0.8:1 to about 1.2:1.
[0059] The binders according to the invention are prepared by
mixing the individual components either in the absence of a solvent
or in the presence of the solvents which are conventionally used in
polyurethane surface coating technology. Suitable solvents include
ethyl acetate, butyl acetate, methoxypropyl acetate, methyl
isobutyl ketone, methyl ethyl ketone, xylene, N-methylpyrrolidone,
petroleum spirit, chlorobenzene, Solvesso solvent or mixtures
thereof.
[0060] Preferably, the ratio by weight of binder components a) and
b) to solvent in the coating compositions according to the
invention is from about 40:60 to about 100:0, more preferably from
about 60:40 to about 100:0.
[0061] The coating compositions may also contain the known
additives from surface coating technology. These include pigments,
fillers, flow control agents, catalysts and anti-settling
agents.
[0062] The properties of the coatings obtained from the coating
compositions according to the invention may be adjusted by
appropriate selection of the type and ratios of starting components
a), b1) and b2).
[0063] The coating compositions may be applied to any substrate in
a single layer or in several layers by known methods, e.g., by
spraying, painting, immersing, flooding or by using rollers or
spreaders. The coating compositions according to the invention are
suitable for preparing coatings on substrates, such as metals,
plastics, wood or glass. The coating compositions are especially
suitable for coating steel sheeting, which is used for the
production of vehicle bodies, machines, cladding panels, barrels
and containers. The substrates may be provided with suitable primer
coats prior to applying the coating compositions according to the
invention. Drying of the coatings may take place at a temperature
of about 0 to 160.degree. C.
[0064] The process for producing coatings using the aspartates of
the present invention may also be used for the production of
prepolymers containing urea, urethane, allophanate and/or biuret
structures.
[0065] The aspartates of the present invention may be directly used
after completion of the synthesis process because, in contrast to
prior art aspartates, an approximately complete degree of
conversion is achieved. As a result of the low concentration of
maleates, fumarates and primary amino groups, these products are
toxicologically and physiologically harmless. They also exhibit a
reasonable, as opposed to a vigorous, reactivity towards
isocyanates. Due to their low viscosity, they are a more than
suitable alternative, as reactive diluents, to the environmentally
polluting organic solvents previously used and may therefore be
used in high quality, low-solvent or even solvent-free, high
solids, two-component coating compositions.
[0066] All parts and percentages in the examples which follow are
by weight, unless otherwise indicated.
EXAMPLE 1
[0067] A round bottom flask was fitted with stirrer, heating
mantle, nitrogen inlet, thermocouple and addition funnel. 58 parts
(1.0 eq.) of 2-metyl-1,5-pentandiamine was added to the flask at
room temperature. 137.7 parts (0.8 eq.) of diethyl maleate was
added through the addition funnel over a period of sixty minutes.
The temperature of the flask rose to 35.degree. C. The reaction was
heated to 60.degree. C. and held for seven hours at which time an
iodometric titration showed that the reaction was complete. The
reaction mixture was cooled to room temperature. 25.02 parts (0.2
eq.) of N-ethylmaleimide was added. The temperature was held at
25.degree. C. for eight hours until the reaction was complete. The
clear, nearly colorless final product had a viscosity of 260 cps
and an amine number of 251 (theoretical amine number: 253).
EXAMPLE 2
[0068] A round bottom flask was fitted with stirrer, heating
mantle, nitrogen inlet, thermocouple and addition funnel. 105 parts
(1.0 eq.) of bis-(paraaminocyclohexyl)methane was added to the
flask at room temperature. 129 parts (0.75 eq.) of diethyl maleate
was added through the addition funnel over a period of sixty
minutes. The temperature of the flask rose to 33.degree. C. The
reaction was heated to 60.degree. C. and held for ten hours at
which time an iodometric titration showed that the reaction was
complete. The reaction mixture was cooled to room temperature.
31.28 parts (0.25 eq.) of N-ethylmaleimide was added. The
temperature was held at 25.degree. C. for eight hours, after which
time the reaction was complete. The clear, nearly colorless final
product had a viscosity of 6300 cps and an amine number of 209
(theoretical amine number: 211).
EXAMPLE 3
[0069] A round bottom flask was fitted with stirrer, heating
mantle, nitrogen inlet, thermocouple and addition funnel. 85 parts
(1.0 eq.) of 5-amino-1,3,3-trimethylcyclohexanemethylamine
("isophorone diamine") was added to the flask at room temperature.
137.7 parts (0.80 eq.) of diethyl maleate was added through the
addition funnel over a period of sixty minutes. The temperature of
the flask rose to 35.degree. C. The reaction was heated to
60.degree. C. and held for ten hours at which time an iodometric
titration showed that the reaction was complete. The reaction
mixture was cooled to room temperature. 25.1 parts (0.20 eq.) of
N-ethylmaleimide was added. The temperature was held at 25.degree.
C. for eight hours, after which time the reaction was complete. The
clear, nearly colorless final product had a viscosity of: 2070 cps
and an amine number of 223 (theoretical amine number: 227).
[0070] The samples from the Examples were hand mixed with Desmodur
N-3300 (a trimerized hexane diisocyanate having an NCO content of
21.8% and an equivalent weight of 192), at a NCO to NH equivalent
ratio of 1. Viscosity was measured on a Brookfield Viscometer.
Sample drytime was measured by doing a drawdown of the mixed sample
on glass. Samples were drawn down at 10 mils wet. At 2 minute
intervals, a cotton ball was pressed on the drawdown to test for
film cure. The sample film was completely cured when the cotton
ball did not leave an imprint. Shore D Hardness was measured by
pouring the mixed sample into an aluminum cup and testing for
hardness 3 days later with a Shore Durometer Type D-2, ASTM D2240.
Results were as reported in the following table:
1 Drytime, Potlife, Appearance of minutes mins. Shore D film
Example <2 <2 79 Clear 1 Example 10 8 75 Clear 2 Example 25
20 75 Clear 3 (Shore D hardness - 3 days after mix)
[0071] 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 except as it may be limited
by the claims.
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