Polyaddition product containing isocyanurate groups and uretdione groups, and a process for preparing same

Isocyanurate- and uretdione-group-containing polyaddition product of an isophorone diisocyanate comprising the reaction product of: PA1 i) an isophorone diisocyanate which contains isocyanurate groups and uretdione groups; and PA1 ii) a diol component selected from the group consisting of a diol, a disecondary diamine, a linear hydroxyl-containing polyester and a mixture thereof, PA1 wherein said isophorone diisocyanate comprises not more than 2% by weight of free isophorone diisocyanate and .gtoreq.5 wt. % of isophorone diisocyanate isocyanurate, PA1 wherein said isophorone diisocyanate is reacted with said diol component in an NCO/OH ratio of 1:0.5-1:0.95 and/or an NCO/NH ratio of 0.5:1 0.95:1.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a novel isocyanurate and 
uretdione-group-containing polyaddition product and a process for 
preparing same. 
2. Discussion of the Background 
DE-C 30 30 572 (U.S. Pat. No. 4,483,798) describes polyaddition products 
which contain uretdione groups and have in the meantime acquired economic 
importance for the preparation of PU powders free from blocking agents. 
These compounds claimed in DE-C 30 30 572 are polyaddition compounds of an 
isophorone diisocyanate (IPDI) which contains uretdione groups but no 
isocyanurate groups (referred to in the following text as isophorone 
diisocyanate uretdione and in abbreviated form as IPDI uretdione) and 
diols, the resulting addition product being reacted, if desired and wholly 
or partially, with monoalcohols and/or monoamines. 
A prerequisite for the preparation of the uretdione-group-containing 
polyaddition products from IPDI uretdione and diols is, as stated in DE-A 
30 30 572, p. 1, lines 20-35, a substantially isocyanurate-free IPDI 
uretdione, which is described in DE-C 30 30 513 (U.S. Pat. No. 4,476,054) 
and DE-A 37 39 549 (U.S. Pat. No. 4,912,210). DE-C 30 30 513 describes the 
dimerization of IPDI with tris(dialkylamino)phosphines, in DE-A 37 39 549 
with 4-dialkylamino-substituted pyridine. 
These uretdione-group-containing polyaddition products, which are prepared 
on the industrial scale, have a series of disadvantages which lie in the 
quality of the IPDI uretdione employed. For example, long reaction times 
are necessary for the dimerization of IPDI with substituted pyridines. 
Moreover, the IPDI uretdiones prepared in this way possess, as described 
in EP 0 478 990, a strong inherent color. It is also necessary to 
deactivate the pyridine residues present in the IPDI uretdione. 
It would be highly advantageous and desirable, in preparing a 
uretdione-group-containing polyaddition product, to be able to employ an 
IPDI uretdione which was not hampered by the above-mentioned disadvantages 
of the IPDI uretdione which is currently employed. 
It has surprisingly been found that it is possible to employ a IPDI 
uretdione further comprising isocyanurate groups (trimer of IPDI 
(isophorone diisocyanate isocyanurate)), such as that prepared in 
accordance with the teaching of DE-A 19 34 763 for the preparation of the 
uretdione-group-containing polyaddition products. This was all the more 
surprising since it is expressly stated in DE-C 30 30 572 that an IPDI 
uretdione prepared according to DE-A 19 34 763, which still contains 
20-40% by weight of the trimeric IPDI (IPDI isocyanurate) in the mixture, 
is unsuitable for specific subsequent reaction with, for example, diols. 
SUMMARY OF THE INVENTION 
The invention provides isocyanurate- and uretdione-group-containing 
polyaddition product comprising the reaction product of: 
i) an isophorone diisocyanate which contains isocyanurate groups and 
uretdione groups; and 
ii) a diol component selected from the group consisting of a, a disecondary 
diamine, a linear hydroxyl-containing polyester and a mixture thereof, 
wherein said isophorone diisocyanate comprises not more than 2% by weight 
of free isophorone diisocyanate and .gtoreq.5 wt. % of isophorone 
diisocyanate isocyanurate, 
wherein said isophorone diisocyanate is reacted with said diol component in 
an NCO/OH ratio of 1:0.5-1:0.95 and/or an NCO/NH ratio of 0.5:1 0.95:1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The isocyanurate- and uretdione-group-containing isophorone diisocyanate 
employed in accordance with the invention, which will be referred to below 
in abbreviated form as IPDI-UD/T, preferably contains &lt;2 wt. % of free 
IPDI, more preferably .ltoreq.1 wt. % of free IPDI, even more preferably 
.ltoreq.0.5 wt. %. 
The IPDI-UD/T preferably contains .gtoreq.5 wt. % of IPDI isocyanurate, 
more preferably .gtoreq.10 wt. %, even more preferably .gtoreq.15 wt. %, 
even more preferably .gtoreq.20 wt. % and preferably .ltoreq.40 wt. % of 
IPDI isocyanurate. 
The IPDI-UD/T preferably contains .ltoreq.95 wt. % of IPDI uretdione, more 
preferably .ltoreq.90 wt. %, even more preferably .ltoreq.85 wt. %, even 
more preferably .ltoreq.80 wt. % and preferably .gtoreq.60 wt. % IPDI 
uretdione. 
IPDI-UD/T, may be prepared by reacting IPDI using the catalysts described 
in DE-A 19 34 763. In this reaction, IPDI is reacted with 1-2% by weight 
of tributylphosphine at room temperature for 10-40 h. The longer the 
reaction of the IPDI, the higher the content of isocyanurate groups in the 
reaction mixture. The unreacted free IPDI is separated off from the 
reaction product by thin-film distillation at 100.degree.-140.degree. 
C./0.1 mbar. The IPDI-freed reaction product contains .ltoreq.1% of free 
IPDI and has an NCO content of 17-18%; the content of IPDI isocyanurate 
may vary depending on the IPDI conversion, from 20 to a maximum of 30% by 
weight. 
In the reaction of IPDI-UD/T with the diol component it is possible in this 
case to use a procedure in which the diol component is introduced in one 
go or else is added to the IPDI-UD/T by gradual introduction. 
Preferably, the reactants are mixed in the stated ratios. Then the 
IPDI-UD/T is introduced and the diol component is added. The reaction is 
carried out in the presence of solvents inert toward isocyanates at from 
20.degree. to 90.degree. C. Non-limiting examples of suitable solvents are 
aromatic hydrocarbons, such as toluene or xylene, chlorobenzene, 
nitrobenzene and ketones, such as acetone, methyl isobutyl ketone, 
cyclopentanone and cyclohexanone, or esters such as ethyl acetate and 
butyl acetate. 
Non-limiting examples of such diol components are diols such as ethylene 
glycol, 1,2- and 1,3-propylene glycol, 2-ethylhexane-1,3-diol, hexanediol, 
octanediol, decanediol, dodecanediol, neopentyl glycol, 
1,4-bishydroxymethylcyclohexane, 3(4),8(9)-bishydroxymethyltricyclodecane, 
2-methylpropane-1,3-diol, 3-methylpentane-1,5-diol, diethylene glycol and 
neopentyl glycol hydroxypivalate, 1,4-butanediol, as a linking diol, is 
preferably employed for synthesizing the isocyanurate-group-containing 
polyuretdione-polyurethanes according to the invention. 
As diol components it is also possible, advantageously, to employ linear 
hydroxyl-containing polyesters with a molar mass of between 250 and 2,000, 
preferably 300-1,500, as chain extenders for IPDI-UD/T. They may be 
prepared by, for example, combining diols and dicarboxylic acids. In 
addition to the above-mentioned diols trans- and cis-cyclohexanedimethanol 
(CHDM) are preferably employed for preparing the chain extenders. The 
preferred dicarboxylic acids include aliphatic, optionally alkyl-branched 
acids, such as succinic, adipic, suberic, azelaic and sebacic acid and 
2,2,4(2,4,4)-trimethyladipic acid; also included herein are lactones and 
hydroxycarboxylic acids, such as .epsilon.-caprolactone and hydroxycaproic 
acid. The diol/chain extender mixtures employed in the novel process are 
in a ratio of from 5:95. 
The reaction generally takes place at temperatures of 60.degree.-90.degree. 
C. The reaction components are heated at the temperatures indicated until 
all OH groups have reacted to form urethane groups. Depending on the 
reaction temperature, this takes 0.5-5 h. In order to accelerate the 
reaction it is also possible to employ catalysts, such as tin(II) acetate, 
tin(II) octoate, tin(II) laurate, dibutyltin diacetate, dibutyltin 
dilaurate, dibutyltin maleate or dioctyltin diacetate. 
The reaction mixtures are generally worked up by freeing the 
isocyanurate-group-containing polyuretdione-polyurethanes from any solvent 
used. Suitable apparatus for this are evaporating screws, filmtruders or 
else spray driers. 
A particularly advantageous variant of the invention consists in reacting 
the described reaction products (having free NCO groups) with monoalcohols 
in such a way that all or at least some of the NCO groups are reacted. The 
procedure comprises reacting the IPDI-UD/T with the component ii) (i.e. 
diol, disecondary diamine, or the linear hydroxyl-containing polyester) 
under the conditions already described and, after the reaction, not 
cooling the reaction product but adding the monoalcohol while retaining 
the temperature. The reaction mixture is then heated further until the 
equivalent amount of NCO per equivalent of OH employed has been reacted. 
The reaction products are isolated in a manner similar to that described 
above. Suitable monohydric alcohols are methanol, ethanol, n-butanol, 
2-ethylhexanol and n-decanol. In place of the monoalcohols it is also 
possible to employ primary or secondary monoamines. Examples of suitable 
monoamines are n-propylamine, n-butylamine, n-hexylamine and dibutylamine. 
A particularly advantageous variant of the invention consists in reacting 
IPDI-UD/T with the diol component and/or the OH-containing linear 
polyesters (OH-containing chain extenders) such that the reaction products 
contain terminal OH groups, i.e. such that the IPDI-UD/T is reacted with 
the diol component and/or chain extender in an NCO/OH ratio of 
0.5:1-0.95:1. These polyaddition compounds of IPDI-UD/T and diols and/or 
chain extenders have the feature, relative to their counterparts 
containing NCO groups and/or urethane or urea groups, of being of 
heightened reactivity (under hot conditions) with respect to OH-containing 
reactants. 
If, in accordance with the invention, disecondary diamines are employed as 
component ii) instead of diols or OH-containing chain extenders, it has 
been found particularly advantageous to operate at room temperature in 
solution. The disecondary diamine is added a little at a time in the 
proportion indicated to the dissolved IPDI-UD/T at a rate such that the 
temperature of the reaction mixture does not exceed 40.degree. C. After 
the diamine has been added the reaction is at an end and, if the reaction 
products contain free NCO groups or secondary amino groups, the 
solvent--generally acetone--is removed as above for the corresponding 
IPDI-UD/T-diol adducts. If the free NCO groups of the reaction products 
are to be reacted wholly or partially with monoalcohols, the monoalcohol 
is added to the reaction mixture after the diamine has been added and the 
mixture is heated at 60.degree. C. until 1 NCO equivalent has reacted per 
equivalent of OH employed. The solvent is then removed as already 
described a number of times. 
The diamines to be employed in accordance with the invention may be 
disecondary diamines which are prepared in two stages, the 1st stage 
comprising condensation of a (cyclo)aliphatic diamine having two primary 
amino groups with an aldehyde or ketone to form the Schiff base, and the 
2nd stage comprising hydrogenation of the Schiff base. For the 
condensation reaction to form the Schiff base, suitable diamines are in 
principle all (cyclo)aliphatic diamines, examples being ethylenediamine, 
1,2-diaminopropane, 2-methylpentamethylenediamine, hexamethylenediamine, 
2,2,4(2,4,4)-trimethylhexamethylenediamine, isophoronediamine (IPD), 
1,2-diaminocyclohexane and 1,3-bis(aminomethyl)benzene. Suitable carbonyl 
compounds to be employed for the preparation of the Schiff base are in 
principle all (cyclo)aliphatic aldehydes and ketones; however, preference 
is given to the use of isobutyraldehyde, 2-ethylhexanal, methyl ethyl 
ketone, methyl isobutyl ketone, diisobutyl ketone, cyclohexanone and 
3,5,5-trimethylcyclohexanone. A particularly advantageous variant of the 
process according to the invention consists in employing disecondary 
diamines as are obtained by reaction of diprimary diamines with acrylates, 
for example methyl, ethyl, butyl or 2-ethylhexyl acrylate. The reaction of 
the diamine with the acrylate takes place at 60.degree.-80.degree. C. in a 
molar ratio of 1:2. 
The present invention additionally provides the polyaddition products 
containing isocyanurate groups and uretdione groups which have been 
prepared as claimed from isophorone diisocyanate which contains 
isocyanurate groups and uretdione groups and has been prepared using 
tertiary phosphines, and from diols and/or linear hydroxyl-containing 
polyesters having a molar mass of 250-2,000, preferably 300-1,500, and, if 
desired, monoalcohols and/or monoalmines. 
The polyaddition products according to the invention, namely 
1. adducts having terminal free NCO groups; 
2. those whose NCO groups are reacted wholly or partially with monoalcohols 
or monoamines; and 
3. those with terminal OH groups are generally compounds with a molecular 
weight (Mn) in the range 1,500-10,000, preferably 3,000-7,000. The 
polyaddition products have a melting point of 80.degree.-160.degree. C., 
preferably 90.degree.-130.degree. C. 
The compounds according to the invention are particularly suitable as 
hardeners for (thermoplastic) compounds of relatively high functionality 
having Zerewitinoff active hydrogen atoms. In combination with such 
compounds having Zerewitinoff active hydrogen atoms, the polyaddition 
products form systems which can be cured above 160.degree. C., preferably 
180.degree. C., to form high-grade plastics. The most important area of 
application for such systems is that of PU powder coatings. 
Having generally described this invention, a further understanding can be 
obtained by reference to certain specific examples which are provided 
herein for purposes of illustration only and are not intended to be 
limiting unless otherwise specified. 
EXPERIMENTAL SECTION 
I. Preparation of the Isophorone Diisocyanate Containing Isocyanurate 
Groups and Uretdione Groups (IPDI-UD/T) 
1,000 parts by weight of IPDI are left to react with 10 parts by weight of 
tributylphosphine at room temperature for about 40 h. When the reaction 
mixture has an NCO content of about 32%, the unreacted IPDI is separated 
off together with the catalyst in a thin-film evaporator at 140.degree. 
C./0.1 mbar. 
The residue, the isophorone diisocyanate containing isocyanurate groups and 
uretdione groups, contains 1% by weight of IPDI and has an NCO content of 
17.4%. After heating at 180.degree. C. for 1 h the NCO content is 32.8%. 
The tributylphosphine content is 0.07%. 
II. General Preparation Procedure for the Hydroxyl-Containing Linear 
Polyesters 
The starting components are placed in a reactor and are heated to about 
140.degree. C. with the aid of an oil bath. After the substances have 
predominantly melted, 0.1% by weight of di-n-butyltin oxide is added as 
catalyst. Initial elimination of H.sub.2 O occurs at about 150.degree. C. 
The temperature is raised to about 190.degree. C. over the course of 2-3 h 
and the esterification is brought to an end over the course of about 10 h. 
Throughout the reaction period the mixture is stirred and a gentle stream 
of nitrogen is passed through the reaction mixture. The acid number of the 
polyesters was in each case &lt;2 mg of KOH/g. 
1. 1 mol of adipic acid and 2 mol of neopentyl glycol (NPG) were reacted in 
accordance with the general preparation procedure. The reaction product 
had the following characteristics: 
OH number mg of KOH/g!: 340.+-.10 
viscosity mPa.s! at 25.degree. C.: 1,600.+-.200 
2. 1.25 mol of adipic acid and 2.25 mol of NPG were reacted in accordance 
with the general preparation procedure. The reaction product had the 
following characteristics: 
OH number mg of KOH/g!: 290.+-.15 
viscosity mPa.s! at 25.degree. C.: 2,000.+-.200 
3. 4 mol of adipic acid, 3 mol of NPG and 2 mol of hexanediol were reacted 
in accordance with the general preparation procedure. The reaction product 
had the following characteristics: 
OH number mg of KOH/g!: 105.+-.10 
viscosity mPa.s! at 25.degree. C.: 3,400.+-.300 
III. Disecondary Diamines 
The diamines (1-3) employed in the process according to the invention were 
prepared in a known manner by reacting the diamine with the carbonyl 
compound (in Example 3.: vice versa) followed by hydrogenation. 
1. N,N'-diisobutylisophoronediamine 
2. 1,1,6,6-tetraisopropyl-2,5-diazahexane 
3. N,N'-di-tert-butylethylenediamine 
4. The diamine in this example (4) was prepared by reacting 1 mol of 
isophorone diamine and 2 mol of t-butyl acrylate. Its amine equivalent 
weight was 214. 
IV. General Preparation Procedure for the Polyaddition Compounds According 
to the Invention Containing Isocyanurate Groups and Uretdione Groups 
1. IPDI-UD/T and diols/OH-containing linear poly-ester 
The polyol component and the IPDI-UD/T are dissolved in acetone to give a 
solution with a strength of about 50%. 0.02% by weight of dibutyltin 
dilaurate is added with vigorous stirring under an inert gas atmosphere 
and the mixture is heated at boiling until 1 NCO equivalent has reacted 
per mole of OH groups. This takes about 3-4 h. 
If the free NCO groups are also to be blocked with monoalcohols, the 
monoalcohol is added at this point and heating is continued until 1 NCO 
equivalent has reacted per mole of monoalcohol. Following reaction, the 
acetone is distilled off. A vacuum is applied in order to remove the last 
traces of acetone. 
2. IPDI-UD/T and disecondary diamines 
The IPDI-UD/T is dissolved in acetone. The disecondary diamine is added at 
room temperature with intense stirring at a rate such that the temperature 
does not rise above 40.degree. C. After the diamine has been added the 
reaction is over; the acetone is then separated off as described under 
IV.1. 
If the free NCO groups of the reaction product are also to be blocked 
wholly or partially with a monoalcohol, then before separating off the 
acetone the monoalcohol is added to the acetone solution together with 
0.02% of DBTL and the mixture is heated at 60.degree. C. until 1 NCO 
equivalent has reacted per mole of monoalcohol. The acetone is then 
separated off as under IV.1. 
__________________________________________________________________________ 
Composition in mol Chemical and physical 
characteristics 
Example OH-containing 
Disecondary NCO content (% by weight) 
Melting 
Glass transition 
No. IPDI-UD/T 
Diol polyester 
diamine 
R--OH/R.sub.2 NH 
free total .degree.C. 
temperature 
.degree.C.! 
__________________________________________________________________________ 
1 3 2 B -- -- -- 4.7 18.5 108-115 
75-91/82 
2 4 3 B -- -- -- 3.4 17.0 111-117 
77-93/85 
3 5 4 B -- -- -- 2.6 16.1 115-122 
82-97/91 
4 10 9 B -- -- -- 1.1 14.3 126-140 
88-105/94 
5 10 11 B -- -- -- 0.1 11.0 108-116 
80-95/90 
6 15 14 B -- -- 2C.sub.8 H.sub.17 OH 
0.3 12.3 130-142 
101-115/107 
7 15 14 CHDM 
-- -- 2HN(C.sub.4 H.sub.2).sub.2 
0.1 11.2 164-170 
112-125/118 
8 15 13 B 10.1 -- -- 0.5 12.4 125-136 
89-106/95 
9 15 12 B 20.2 -- -- 0.4 11.9 121-132 
85-101/91 
10 5 -- -- 4 IPD-A 140 
-- 1.9 12.5 146-161 
125-142/133 
11 10 -- -- 9 DTB-EDA 
-- 1.1 10.7 125-140 
101-119/109 
12 10 -- -- 9 EDA 128 
-- 0.8 9.6 151-159 
133-151/141 
__________________________________________________________________________ 
B: butanediol 
CHDM: 1,4bis(hydroxymethyl)cyclohexane 
IPDA 140: N,Ndiisobutylisophoronediamine 
DTBEDA: N,Ndi-tert-butylethylenediamine 
EDA 128: 1,1,6,6tetraisopropyl-2,5-diazahexane 
Obviously, numerous modifications and variations of the present invention 
are possible in light of the above teachings. It is therefore to be 
understood that within the scope of the appended claims, the invention may 
be practiced otherwise than as specifically described herein. 
This application is based on German patent application DE 19 60 6030.3 
filed in the German Patent Office on Feb. 19, 1996, the entire contents of 
which are hereby incorporated by reference.