HK1093077B - Reactive polyurethane prepolymers with low monomeric diisocyanate content - Google Patents

Description

Reactive polyurethane prepolymers with low monomeric diisocyanate content

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority from german application DE 102004060284 filed on 12, 15/2004.

Technical Field

The present invention relates to reactive polyurethanes with a low content of monomeric diisocyanates and also to their preparation and to their use in reactive one-and two-component adhesives/sealants, assembly foams, casting compounds, and flexible, rigid and integral foams.

Background

In these applications, substances known as isocyanate (NCO) prepolymers are generally used, which can then be cured with water (known as 1K 1-component systems) or with alcohols or amines (known as 2K 2-component systems). These NCO prepolymers preferably contain terminal isocyanate (NCO) groups.

To obtain polyurethanes containing terminal NCO groups, the polyfunctional alcohols are generally reacted with an excess of monomeric polyisocyanates, usually diisocyanates, and any unreacted isocyanates are removed again after the reaction.

However, residual monomer contents which are too high for products to be used as low-monomer-content products which do not need to be marked in adhesive and sealant field products are generally obtained, which can also be processed at high service temperatures without increased workplace safety measures.

Furthermore, the monomeric isocyanates contained in the coatings, adhesive bonds or sealants can migrate over time or can lead to CO by reaction with atmospheric moisture₂And the liberation of the corresponding amine, which in turn can give rise to other undesirable qualities.

In the field of food packaging, the amount of amines, in particular primary aromatic amines, which are formed as a result of the transfer of diisocyanates must be below the limit of detection of anilino hydrochloride of 0.2. mu.g of aniline hydrochloride per 100ml of sample (Bundesinstitut fur sundhedilichen Verbrauchutzund Veterin)rmedizin [ German Federal Consumer Health Protection and veterinary Medicine Institute (German Federal Institute of Consumer Health Protection and veterinary Medicine)]BGVV, collected according to the statutory guidelines for the analysis method according to § 35LMBG [ German Food and daily article regulations (German Food and Commoditie Sact)]Analysis of the food/determination of the primary aromatic amines in aqueous test foods).

There is therefore a need for reactive polyurethanes and/or polyurethane prepolymers having a significantly reduced fraction of monomeric diisocyanates, preferably below 0.1% by weight, and reactive one-and two-component adhesives/sealants, assembly foams, casting compounds, and flexible, rigid and integral foams based thereon.

It is furthermore desirable that the NCO prepolymers produced have a particularly low viscosity, so that no additional solvents have to be added to adjust the viscosity during processing and use of the adhesives and sealants, if possible.

To prepare such NCO-functional prepolymers which meet the above conditions in the sealant and adhesive field, typically organotin compounds such as dibutyltin Dilaurate (DBTL) or bismuth carboxylates are used.

However, tin compounds are hindered by their toxicity, especially in food contact. Bismuth carboxylates are on the contrary considered toxicologically unanimous, they lead to a somewhat higher viscosity in the end product and also to a very low residual monomer content.

Disclosure of Invention

It was therefore an object of the present invention to find catalysts which give at least the same low residual monomer content in the prepolymer as when using the abovementioned classes of catalysts, but which do not have the toxicity of tin compounds and give prepolymers which preferably have a lower viscosity than prepolymers prepared analogously using bismuth catalysts.

It has now surprisingly been found that particular fluorine-bearing zirconium (IV) acetylacetonate complexes achieve the stated object.

The present invention therefore provides the use of zirconium (IV) acetylacetonate complexes as urethanization catalysts, at least one acetylacetonate ligand present in the catalyst bearing a fluorine substituent.

Accordingly, in one aspect, the present invention provides a process for the preparation of a carbamate-containing compound, the process comprising the step of reacting an isocyanate-containing compound with an isocyanate-reactive compound in the presence of a zirconium (IV) acetylacetonate complex as catalyst, wherein at least one acetylacetonate ligand present in the catalyst bears a fluorine substituent.

Also provided by the present invention is a process for preparing NCO-functional polyurethane prepolymers having a NOC content of from 0.2% to 12% by weight, in which at least one monomeric asymmetric diisocyanate having a molecular weight of from 160g/mol to 500g/mol and at least one polyether polyol and/or polyester polyol are reacted with one another in a ratio of isocyanate groups to hydroxyl groups of from 1.05: 1 to 2.0: 1 in the presence of zirconium (IV) acetylacetonate complexes, at least one of the acetylacetonate ligands present in the catalyst carrying a fluorine substituent.

Detailed Description

As used herein, for example, and unless otherwise expressly specified, all numbers may be read as if prefaced by the word "about", even if the term does not expressly appear. Also, any numerical range recited herein is intended to include all sub-ranges subsumed therein.

The zirconium (IV) acetylacetonate complexes for use in the present invention preferably carry at least one CF₃Each acetylacetonate ligand, and particularly preferably zirconium (IV) acetylacetonate complexes, comprises exclusively at least one CF₃A radical acetylacetonate ligand. Very particular preference is given to tris (1, 1, 1-trifluoro-acetylacetonato) zirconium (IV) and tris (1, 1, 1, 5, 5, 5-hexafluoroacetylacetonato) zirconium (IV).

Further provided by the present invention is a process for preparing NCO-functional polyurethane prepolymers having a NOC content of from 0.2% to 12% by weight, wherein at least one monomeric asymmetric diisocyanate having a molecular weight of from 160g/mol to 500g/mol and at least one polyether polyol and/or polyester polyol are reacted with one another in a ratio of isocyanate groups to hydroxyl groups of from 1.05: 1 to 2.0: 1 in the presence of zirconium (IV) acetylacetonate complexes, at least one of the acetylacetonate ligands present in the catalyst carrying a fluorine substituent.

The NCO content of the reactive polyurethane prepolymers thus obtainable is preferably from 0.5% to 10% by weight and particularly preferably from 1.0% to 8% by weight.

The monomeric asymmetric diisocyanates A) used for the purposes of the present invention are aromatic, aliphatic or cycloaliphatic diisocyanates having molecular weights of from 160g/mol to 500g/mol, which have NCO groups of different reactivity with polyols. The different reactivity of the NCO groups of the diisocyanates is brought about by different adjacent substituents to the NCO groups on the molecule, which are shielded by steric shielding, for example by reducing the reactivity of one NCO group compared with another NCO group, and/or by different bonding of the NCO groups to the remainder of the molecule, for example in the form of primary or secondary NCO groups.

Examples of suitable aromatic asymmetric diisocyanates are 2, 4-tolylene diisocyanate (2, 4-TDI), naphthalene-1, 8-diisocyanate (1, 8-NDI) and diphenylmethane 2, 4 '-diisocyanate (2, 4' -MDI).

Examples of suitable cycloaliphatic asymmetric diisocyanates are 1-isocyanatomethyl-3-isocyanato-1, 5, 5-trimethylcyclohexane (isophorone diisocyanate, IPDI), 1-methyl-2, 4-diisocyanatocyclohexane or the hydrogenation products of the abovementioned aromatic diisocyanates, in particular hydrogenated 2, 4' -MDI.

Examples of aliphatic asymmetric diisocyanates are 1, 6-diisocyanato-2, 2, 4-trimethylhexane, 1, 6-diisocyanato-2, 4, 4-trimethylhexane and lysine diisocyanate. Preferred asymmetric diisocyanates are 2, 4-tolylene diisocyanate (2, 4-TDI), diphenylmethane 2, 4 '-diisocyanate (2, 4' -MDI) and 1-isocyanatomethyl-3-isocyanato-1, 5, 5-trimethylcyclohexane (isophorone diisocyanate, IPDI).

In the context of the present invention, diphenylmethane 2, 4 ' -diisocyanate (2, 4 ' -MDI) comprises polyisocyanates having a 2, 4 ' -MDI content of more than 95% by weight, more preferably more than 97.5% by weight. In addition, the 2, 2' -MDI content is less than 0.5% by weight, more preferably less than 0.25% by weight.

In the context of the present invention, 2, 4-tolylene diisocyanate (2, 4-TDI) comprises a polyisocyanate having a 2, 4-TDI content of greater than 95% by weight, preferably greater than 97.5% by weight, and very preferably greater than 99% by weight. Polyether polyols and/or polyester polyols known per se from polyurethane chemistry can be used as polyol component B).

Polyether polyols which can be used as polyol component B) are known per se to the person skilled in the art of polyurethane chemistry. They are typically obtained from the reaction of low molecular weight polyfunctional OH or NH-functional compounds as starting materials with cyclic ethers or mixtures of different cyclic ethers. The catalyst used here is a base, such as KOH or a double metal cyanide-based system. Preparation processes suitable for this purpose are known to the person skilled in the art, for example, see U.S. Pat. No. 5, 6486361 or L.E.St.Pierre, polyether moiety I, polyalkylene oxides and other polyethers, eds Norman G.Garlord; high polymer Vol.XIII; interscience Publishers; newark 1963; p.130 and pages below.

Suitable starters preferably contain from 2 to 8, more preferably from 2 to 6, hydrogen atoms capable of polyaddition with cyclic ethers. Examples of such compounds are water, ethylene glycol, 1, 2-or 1, 3-propanediol, 1, 3-butanediol, 1, 4-butanediol, 1, 6-hexanediol, bisphenol A, neopentyl glycol, glycerol, trimethylolpropane, pentaerythritol and sorbitol.

Suitable cyclic ethers include alkylene oxides, such as ethylene oxide, propylene oxide, butylene oxide, epichlorohydrin or styrene oxide or tetrahydrofuran.

Preferred polyether polyols for B) are those based on the above-mentioned starters and comprising propylene oxide, ethylene oxide and/or tetrahydrofuran units, more preferably comprising propylene oxide and/or ethylene oxide units.

The polyether polyols suitable as polyol component B) have number-average molecular weights of 200-20000g/mol, preferably 500-12000g/mol and more preferably 1000-8000 g/mol. A limiting factor for the molecular weight is the OH number of the polyol determined in accordance with DIN 53240.

Polyester polyols which can be used as polyol component B) represent polyesters which contain more than one OH group, preferably two terminal OH groups, in the context of the present invention. Such polyesters are known to those skilled in the art.

Thus, for example, polyester polyols which are produced by reaction of low molecular weight alcohols, in particular ethylene glycol, diethylene glycol, neopentyl glycol, hexanediol, butanediol, propylene glycol, glycerol or trimethylolpropane, with caprolactone can be used. Also suitable as polyfunctional alcohols for the preparation of the polyester polyols are 1, 4-hydroxymethyl-cyclohexane, 2-methyl-1, 3-propanediol, butane-1, 2, 4-triol, triethylene glycol, tetraethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, dibutylene glycol and polybutylene glycol.

Further suitable polyester polyols can be prepared by polycondensation. For example, difunctional and/or trifunctional alcohols may be condensed with substoichiometric amounts of dicarboxylic and/or tricarboxylic acids, or reactive derivatives thereof, to form polyester polyols. Examples of suitable dicarboxylic acids are adipic acid or succinic acid and their higher homologues having up to 16 carbon atoms, and also unsaturated dicarboxylic acids such as maleic acid or fumaric acid, and aromatic dicarboxylic acids, in particular the isomeric phthalic acids, such as phthalic acid, isophthalic acid or terephthalic acid. Examples of suitable tricarboxylic acids include citric acid and 1, 2, 4-trimellitic acid. The acids may be used alone or as a mixture of two or more thereof. Particularly suitable alcohols are hexanediol, butanediol, ethylene glycol, diethylene glycol, neopentyl glycol, 3-hydroxy-2, 2-dimethylpropyl, 3-hydroxy-2, 2-dimethylpropionate or trimethylolpropane or mixtures of two or more thereof.

Particularly suitable acids are phthalic acid, isophthalic acid, terephthalic acid, adipic acid or dodecanedioic acid or mixtures thereof.

High molecular weight polyester polyols include, for example, the reaction products of polyfunctional, preferably difunctional alcohols (optionally together with small amounts of trifunctional alcohols) with polyfunctional, preferably difunctional carboxylic acids. Instead of the free polycarboxylic acids, the corresponding polycarboxylic anhydrides or corresponding polycarboxylic esters with alcohols preferably containing 1 to 3 carbon atoms can be used instead, if possible. The polycarboxylic acids may be aliphatic, cycloaliphatic, aromatic or heterocyclic or both. They may, for example, be optionally substituted by alkyl groups, alkenyl groups, ether groups or halogens. Examples of suitable polycarboxylic acids include succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, phthalic acid, isophthalic acid, terephthalic acid, 1, 2, 4-trimellitic acid, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, tetrachlorophthalic anhydride, endomethylenetetrahydrophthalic anhydride, glutaric anhydride, maleic acid, maleic anhydride, fumaric acid, dimer fatty acids or trimer fatty acids or mixtures of two or more thereof.

Polyesters obtainable from lactones, for example based on epsilon-caprolactone, also known as "polycaprolactone", or, for example, hydroxycarboxylic acids, omega-hydroxycaproic acid, can likewise be used.

However, oleochemical-derived polyester polyols may also be used. For example, such polyester polyols can be prepared by: at least part of the fatty mixture containing ethylenically unsaturated fatty acids is completely ring-opened with one or more epoxidized triglycerides of alcohols containing 1 to 12 carbon atoms, and the triglyceride derivatives are subsequently partly transesterified to form alkyl ester polyols containing 1 to 12 carbon atoms in the alkyl group.

The number-average molecular weight of the polyester polyols used in B) is 200-10000g/mol, preferably 1000-6000 g/mol.

The zirconium compounds used in C) correspond to the above definition of the fluorine-bearing zirconium (IV) acetylacetonate complex to be used.

The reaction of the monomeric asymmetric diisocyanates with the polyols is carried out at temperatures of from 20 ℃ to 150 ℃, preferably from 25 ℃ to 100 ℃ and particularly preferably from 40 ℃ to 80 ℃.

The amount of catalyst used may be from 1 to 10000ppm, preferably from 20 to 1000ppm and particularly preferably from 100 to 500ppm, based on the total solids.

The polyurethane prepolymers of the present invention are preferably prepared in a one-shot process. In this case, the polyols of component B) are mixed individually or as a mixture with the isocyanate component A) and the homogeneous mixture is stirred until a constant NCO value is obtained. The reaction temperature is selected to be from 20 ℃ to 150 ℃, preferably from 25 ℃ to 100 ℃ and more preferably from 40 ℃ to 80 ℃. Preferably both reactants and reaction product are liquid at the reaction temperature chosen so that no additional solvent is required for homogenization and for reducing the viscosity of the reaction mixture.

The preparation of the polyurethane prepolymers containing terminal NCO groups can of course also be carried out continuously in stirred tank cascades or in suitable mixing devices, for example high-speed mixers operating according to the rotor-stator principle.

The NCO content was determined by the customary NCO titration procedure in polyurethane chemistry according to DIN 1242.

To stop the reaction or to deactivate the catalyst, it is optionally possible to add a mineral or organic acid, such as hydrochloric acid, sulfuric acid, phosphoric acid or derivatives thereof, formic acid, acetic acid or another alkanol or an organic acid or an acid-releasing component, such as an acid halide. Examples of suitable acid chlorides are formyl chloride, acetyl chloride, propionyl chloride and benzoyl chloride. It is particularly advantageous to stop the reaction if one of the abovementioned known amine or organometallic catalysts is used during the preparation of the prepolymer.

Benzoyl chloride is preferably used as a stopper.

In the case of exclusively polyether polyols as polyol component B), the reactive polyurethane prepolymers of the invention comprise less than 0.3% by weight, preferably less than 0.2% by weight, and particularly preferably less than 0.1% by weight, of monomeric asymmetric diisocyanates.

In addition, a residual monomer content of less than 1.0% by weight, preferably less than 0.5% by weight, is obtained.

The polyurethane prepolymers prepared by the process of the invention exclusively using polyether polyols have a viscosity at 25 ℃ of from 100 mPas to 150000 mPas, preferably from 500 mPas to 100000 mPas and very preferably from 500 mPas to 80000 mPas.

The invention further provides prepolymers obtainable by the process of the invention and also provides their use in the production of polyurethane plastics, coatings, casting compounds, assembly foams, rigid and integral foams, adhesive bonds and/or seals, preferably moisture-curing sealants and/or adhesives based on the prepolymers necessary according to the invention.

Example (b):

all percentages are by weight unless otherwise indicated.

The viscosity was determined using a viskotest VT 550 rotational viscometer from ThermoHaake, Karlsruhe, DE with an SV measuring cup and an SV DIN 2 measuring device at the measurement temperature indicated in each case.

The amount of free monomeric diisocyanate was determined by HPLC after derivatizing the sample with 9- (methylaminomethyl) -anthracene in examples 1-3.

The instrument comprises the following steps: HPLC apparatus: hewlett Packard, HP1050

And (3) detection: fluorescence detector Hewlett Packard, HP1046a

Wavelength: ex. -244 nm, em. -404 nm

Response time 1000ms

PMT increment of 10

Separating the column: LiChrophher 60RP selection for B, 5 μm (125 mm. times.4.0 mm, Merck)

Mobile phase:

eluent A: acetonitrile 100ml, water 900ml, tetrabutylammonium hydrogen sulfate 2g

Eluent B: acetonitrile 900ml, water 100ml, tetrabutylammonium hydrogen sulfate 2g

Gradient: t min A [% ] B [% ]

0 40 60

5 40 60

8 10 90

Flow rate: 1.5ml/min

Total run time: 15min

Posr time: 5min

Temperature: 40 deg.C

Injection volume: 10 μ l

The amount of free monomeric diisocyanate was determined by Gel Permeation Chromatography (GPC) in examples 4-14 and comparative examples 1-5. The measurements were performed at room temperature. The eluent used was THF, the flow rate was 1ml/min and the injection volume was 50. mu.l. The separation column used was packed with 5 μm separation material and had a porosity of 500The GPC column of (MZ-Analyzenchnik, Mainz, MZ-Gel SD-plus). The overall length of the separation column was 120 cm. The detector used is a refractive index detector.

The NCO content of the prepolymer and of the reaction mixture was determined in accordance with DIN EN 1242.

Polyether A:by DMC catalysis through ImpactThe polypropylene glycol prepared by the process has nominal functionality of 2 and hydroxyl value of 56mg KOH/g (Desmophen)2062 BD，Bayer MaterialScience AG，Leverkusen，DE)。

Polyether B:by DMC catalysis through ImpactThe polypropylene glycol prepared by the process has a nominal functionality of 2 and a hydroxyl value of 28mg KOH/g (Acclaim)4200，Bayer Material ScienceAG，Leverkusen，DE)。

Polyether C:by DMC catalysis through ImpactThe polypropylene glycol prepared by the process has a nominal functionality of 2 and a hydroxyl number of 56mg KOH/g (Desmophen 2061 BD, Bayer MaterialScience AG, Leverkusen, DE).

Polyether D:by DMC catalysis through ImpactThe polypropylene glycol prepared by the process has a nominal functionality of 3 and a hydroxyl value of 28mg KOH/g (Acclaim)6300，Bayer Material ScienceAG，Leverkusen，DE)。

Polyether E:polyether polyols having a nominal functionality of 2 and a hydroxyl number of 260mg KOH/g were prepared by propoxylation of propylene glycol (Desmophen 1262 BD, Bayer MaterialScience AG, Leverkusen, DE).

Polyether F:a polyester polyol having a composition of 33.5% by weight of 1, 6-hexanediol, 20.5% by weight of neopentyl glycol and 46.0% by weight of adipic acid, a hydroxyl value of 56mg KOH/g and an acid value of 1.0mg KOH/g.

Catalyst A:zirconium (IV) hexafluoroacetylacetonate, Strem chemicals inc, Kehl, DE.

Catalyst B:zirconium (IV) trifluoroacetylacetonate, Sigma-Aldrich Chemie GmbH, Munich, DE.

Catalyst C:dibutyltin Dilaurate (DBTL), Goldschmidt TIBGmbH, Mannheim DE under the name Tegokat218。

Proglyde DMM: dipropylene glycol dimethyl ether

MPA: methoxypropyl acetate

eq cat: val cat, specified amount of material related to the central atom (metal)

The cat proportion is as follows: the amount of catalyst, the more catalyst used, the higher the cat ratio.

Example 1A) -1G)

The reactive polyurethanes according to Table 1 were prepared by introducing 2, 4 '-MDI having a 2, 4' isomer content of at least 97.5% as monomeric asymmetric diisocyanate and heating it to 50 ℃. The heating is then switched off and polyether A is metered in over the course of 10 minutes. The reaction was continued at a reaction temperature of 80 ℃ for 4 hours. The reaction mixture was then cooled to room temperature and the NOC content, the free unreacted monomeric 2, 4' -MDI content and the viscosity at 23 ℃ were measured. The measured data are reported in table 1.

Table 1: reaction of 2, 4' -MDI with polyether A at different temperatures; the ratio of NCO/OH is 1: 1;

the viscosity was measured at 23 ℃.

Ex.

eq cat

cat ratio

Catalyst and process for preparing same

Temperature of

NCO[％]

Free MDI [ wt.%]

Viscosity [ mPas ]]

1A

5.834E-06

1.0

DBTL

80℃

2.4

0.01

18700

1B

8.75E-06

1.5

Zirconium hexafluoroacetylacetonate (IV)

80℃

2.4

0.01

18500

1C

8.75E-06

1.5

Bismuth 2-ethylhexanoate

80℃

2.5

0.05

20900

1D

8.75E-06

1.5

Is free of

80℃

4.1

n.c.

1950

1E

8.75E-06

1.5

2-Ethylhexanoic acid tin

80℃

2.6

n.c.

31900

1F

8.75E-06

1.5

(1, 5-cyclopentadienyl) (hexafluoroacetylacetonato) silver (I)

80℃

4.1

n.c.

2000

1G

1.167E-05

2.0

Zirconium trifluoroacetylacetonate (IV)

80℃

2.7

n.c.

18700

n.c. ═ incomplete reaction

Example 2A) -2Y)

The reactive polyurethanes according to Table 2 were prepared by introducing 2, 4 '-MDI having a 2, 4' isomer content of at least 97.5% as monomeric asymmetric diisocyanate and heating it to 50 ℃. The heating is then switched off and polyether B is metered in over the course of 10 minutes. The reaction is continued for 2 or 4 hours at a reaction temperature of 60 ℃ or 80 ℃. The reaction mixture was then cooled to room temperature and the NOC content, the free unreacted monomeric 2, 4' -MDI content and the viscosity at 23 ℃ were measured. The measured data are reported in table 2.

Table 2: reaction of 2, 4' -MDI with polyether B at different temperatures; the ratio of NCO/OH is 1: 1;

the viscosity was measured at 23 ℃.

Ex.	eq cat	cat ratio	Catalyst and process for preparing same	Time	Temperature of	NCO[％]	Free MDI [ wt. ]%]	Viscosity [ mPas ]]
									2A	0.0000052	1.0	B(OEt)3	4h	80℃	n.c.
2B	0.0000157	3.0	B(OEt)3	4h	80℃	n.c.
									2C	0.0000052	1.0	Bismuth 2-ethylhexanoate	4h	60℃	1.3	0.01	16900
2D	0.0000079	1.5	Bismuth 2-ethylhexanoate	2h	80℃	1.3	0.07	20100
									2E	7.859E-06	1.5	Bismuth 2-ethylhexanoate	2h	80℃	1.4	0.12	19700
2F	0.0000052	1.0	Bismuth neodecanoate	4h	60℃	1.3	0.01	17100
									2G	0.0000079	1.5	Bismuth neodecanoate	2h	80℃	1.4	0.06	19300
2H	7.859E-06	1.5	Bismuth neodecanoate	2h	80℃	1.4	0.04	20800
									2J	0.0000157	3.0	Borane-pyridine complexes	4h	60℃	n.c.
2K	0.0000157	3.0	Borane-pyridine complexes	4h	60℃	n.c.
									2L	0.0000052	1.0	DBTL	4h	60℃	1.4	0.01	15700
2M	0.0000052	1.0	DBTL	2h	80℃	1.3	0.01	17400
									2N	0.0000052	1.0	DBTL	2h	80℃	1.3	0.01	19500
2O	0.0000262	5.0	Sb(OiPr)3	4h	80℃	n.c.
									2P	0.0000052	1.0	2-Ethylhexanoic acid tin	4h	60℃	1.3	0.21	27700
2Q	0.0000079	1.5	2-Ethylhexanoic acid tin	2h	80℃	1.3	0.34	28600
									2R	7.859E-06	1.5	2-Ethylhexanoic acid tin	2h	80℃	1.5	0.38	33100
2S	0.0000157	3.0	Tetra (dimethylamino) silane	4h	60℃	n.c.

2T

0.0000157

3.0

Tetra (dimethylamino) silane

4h

60℃

n.c.

2U

0.0000262

5.0

Ti(OBu)4

4h

60℃

1.4

0.01

19400

2V

0.0000052

1.0

Ti(OBu)4

4h

60℃

n.c.

2W

0.0000157

3.0

Tris (dimethylamino) borane

4h

60℃

n.c.

2X

0.0000262

5.0

VO(OiPr)3

4h

80℃

n.c.

2Y

0.0000052

1.0

2-Ethyl hexanoic acid zinc salt

4h

60℃

1.5

0.04

16400

n.c. ═ incomplete reaction

Example 3A) -3M)

The reactive polyurethanes according to table 3 were prepared by introducing 2, 4 '-MDI having a 2, 4' isomer content of at least 97.5% as monomeric asymmetric diisocyanate in the corresponding concentrations in the solvents indicated in table 3 and heating it to 50 ℃. The heating is then switched off and polyether B is metered in over the course of 10 minutes. The reaction was continued for 4 hours at a reaction temperature of 80 deg.C (run 3 h: 2 h). The reaction mixture was then cooled to room temperature and the NOC content, the free unreacted monomeric 2, 4' -MDI content and the viscosity at 23 ℃ were measured. The measured data are reported in table 3.

Table 3: reaction of 2, 4' -MDI with polyether B at different temperatures; the ratio of NCO/OH is 1: 1;

the viscosity was measured at 23 ℃.

Ex.

eq cat

Ratio of Cat

Catalyst and process for preparing same

Concentration of

Time

Temperature of

NCO[％]

MDI[wt％]

Viscosity [ mPas ]]

3A

0.0000157

3.0

Trifluoroacetylacetone aluminium (III)

10％，MPA

4h

80℃

n.c.

2190

3B

0.0000052

1.0

DBTL

10％，MPA

4h

80℃

1.32

＜0.1

16330

3C

0.0000157

3.0

Hexafluoroacetylacetonato iron (III)

10％，MPA

4h

80℃

1.28

＜0.1

24000

3D

0.0000157

3.0

Ethyl trimethoxy germanium

10％，MPA

4h

80℃

n.c.

？

2140

3E

0.0000157

3.0

Copper (II) ketotrifluoroacetylpropan

10％，MPA

4h

80℃

1.6

0.2

10440

3F

0.0000157

3.0

Hexafluoroacetylacetonatomagnesium (II)

10％，MPA

4h

80℃

n.c.

1940

3G

0.0

Is free of

10％，MPA

4h

80℃

n.c.

2220

3H

7.859E-06

1.5

Trimethylantimony dichloride

10％，MPA

2h

80℃

n.c.

3J

0.0000157

3.0

Yttrium hexafluoroacetylacetonate (III)

10％，MPA

4h

80℃

n.c.

2220

3K

0.0000157

3.0

Hexafluoroacetylacetonatotin (II)

10％，MPA

4h

80℃

1.43

0.2

19550

3L

8.75E-06

1.5

Zirconium hexafluoroacetylacetonate (IV)

10% in ProglydeDMM

4h

80℃

1.32

0.01

16550

3M

1.167E-05

2.0

Zirconium hexafluoroacetylacetonate (IV)

10% in ProglydeDMM

4h

80℃

1.34

＜0.1

18800

n.c. ═ incomplete reaction

Example 4:

20.26g (0.081mol) of 2, 4 '-MDI (2, 4' isomer content > 97.5%) are melted at a temperature of 50 ℃ in a heatable and coolable glass flask with stirrer device and dropping funnel. To the molten diisocyanate, first 30mg of catalyst A and then 179.74g (0.045mol) of polyether B were added with stirring, which were dehydrated beforehand at 100 ℃ and under a vacuum of 15mbar, these additions being carried out such that the temperature at 50 ℃ did not rise. After the polyether had been completely added, the reaction mixture was heated to 60 ℃ and stirred further at this temperature until a constant NCO content of 1.43% (theory: 1.51%) was reached after a reaction time of 4 hours. The catalyst was then deactivated by addition of 45mg of benzoyl chloride and the product was partitioned. The NCO content of the final product was 1.43%.

Example 5:

20.26g (0.081mol) of 2, 4 '-MDI (2, 4' isomer content > 97.5%) are melted at a temperature of 50 ℃ in a heatable and coolable glass flask with stirrer device and dropping funnel. To the molten diisocyanate, first 30mg of catalyst B and then 179.74g (0.045mol) of polyether B were added with stirring, which were dehydrated beforehand at 100 ℃ and under a vacuum of 15mbar, these additions being carried out such that the temperature at 50 ℃ did not rise. After the polyether had been completely added, the reaction mixture was heated to 60 ℃ and stirred further at this temperature until a constant NCO content of 1.42% (theory: 1.51%) was reached after a reaction time of 4 hours. The catalyst was then deactivated by addition of 45mg of benzoyl chloride and the product was partitioned. The NCO content of the final product was 1.42%.

Example 6:

151.53g (0.606mol) of 2, 4 '-MDI (2, 4' isomer content > 97.5%) are melted at a temperature of 50 ℃ in a heatable and coolable glass flask with stirrer device and dropping funnel. To the molten diisocyanate, first 225mg of catalyst A and then a mixture of 269.70g (0.067mol) of polyether B and 1078.77g (0.18mol) of polyether D, which were dehydrated beforehand at 100 ℃ under a vacuum of 15mbar, were added with stirring, these additions being carried out such that the temperature at 50 ℃ did not rise. After the polyether had been completely added, the reaction mixture was heated to 60 ℃ and stirred further at this temperature until a constant NCO content of 1.50% (theory: 1.50%) was reached after a reaction time of 2 hours. The catalyst was then deactivated by addition of 375mg of benzoyl chloride and the product was partitioned. The NCO content of the final product was 1.50%.

Example 7:

151.53g (0.606mol) of 2, 4 '-MDI (2, 4' isomer content > 97.5%) are melted at a temperature of 50 ℃ in a heatable and coolable glass flask with stirrer device and dropping funnel. To the molten diisocyanate, first 225mg of catalyst A and then a mixture of 1078.77g (0.27mol) of polyether B and 269.70g (0.045mol) of polyether D, which was dehydrated beforehand at 100 ℃ and under a vacuum of 15mbar, were added with stirring, these additions being carried out such that the temperature at 50 ℃ did not rise. After the polyether had been completely added, the reaction mixture was heated to 60 ℃ and stirred further at this temperature until a constant NCO content of 1.36% (theory: 1.50%) was reached after a reaction time of 2 hours. The catalyst was then deactivated by addition of 375mg of benzoyl chloride and the product was partitioned. The NCO content of the final product was 1.36%.

Example 8:

32.85g (0.131mol) of 2, 4 '-MDI (2, 4' isomer content > 97.5%) are melted at a temperature of 50 ℃ in a heatable and coolable glass flask with stirrer device and dropping funnel. To the molten diisocyanate, first 30mg of catalyst A and then 167.15g (0.084mol) of polyether C were added with stirring, which were dehydrated beforehand at 100 ℃ and under a vacuum of 15mbar, these additions being carried out such that the temperature at 50 ℃ did not rise. After the polyether had been completely added, the reaction mixture was heated to 60 ℃ and stirred further at this temperature until a constant NCO content of 2.13% (theory: 2.0%) was reached after a reaction time of 2 hours. The catalyst was then deactivated by addition of 40mg of benzoyl chloride and the product was partitioned. The NCO content of the final product was 2.13%.

Example 9:

35.51g (0.142mol) of 2, 4 '-MDI (2, 4' isomer content > 97.5%) are melted at a temperature of 50 ℃ in a heatable and coolable glass flask with stirrer device and dropping funnel. To the molten diisocyanate, first 30mg of catalyst A and then 164.49g (0.082mol) of polyether C were added with stirring, which had been dehydrated beforehand at 100 ℃ and under a vacuum of 15mbar, these additions being carried out such that the temperature at 50 ℃ did not rise. After the polyether had been completely added, the reaction mixture was heated to 60 ℃ and stirred further at this temperature until, after a reaction time of 4 hours, a constant NCO content of 2.46% (theory: 2.5%) was reached. The catalyst was then deactivated by addition of 40mg of benzoyl chloride and the product was partitioned. The NCO content of the final product was 2.46%.

Example 10:

36.68g (0.147mol) of pure 2, 4 '-MDI (2, 4' isomer content > 97.5%) are melted at a temperature of 50 ℃ in a heatable and coolable glass flask with stirrer device and dropping funnel. To the molten diisocyanate, first 30mg of catalyst A and then 163.32g (0.082mol) of polyether C were added with stirring, which had been dehydrated beforehand at 100 ℃ and under a vacuum of 15mbar, these additions being carried out such that the temperature at 50 ℃ did not rise. After the polyether had been completely added, the reaction mixture was heated to 60 ℃ and stirred further at this temperature until a constant NCO content of 2.69% (theory: 2.74%) was reached after a reaction time of 5 hours. The catalyst was then deactivated by addition of 40mg of benzoyl chloride and the product was partitioned. The NCO content of the final product was 2.69%.

Example 11:

96.16g (0.385mol) of pure 2, 4 '-MDI (2, 4' isomer content > 97.5%) are melted at a temperature of 50 ℃ in a heatable and coolable glass flask with stirrer device and dropping funnel. To the molten diisocyanate, first 30mg of catalyst A and then 103.86g (0.242mol) of polyether E were added with stirring, which were dehydrated beforehand at 100 ℃ and under a vacuum of 15mbar, these additions being carried out such that the temperature at 50 ℃ did not rise. After the polyether had been completely added, the reaction mixture was heated to 60 ℃ and stirred further at this temperature until a constant NCO content of 5.67% (theory: 6.0%) was reached after a reaction time of 3.5 hours. The catalyst was then deactivated by addition of 40mg of benzoyl chloride and the product was partitioned. The NCO content of the final product was 5.67%.

Example 12:

47.7g (0.191mol) of pure 2, 4 '-MDI (2, 4' isomer content > 97.5%) are melted at a temperature of 50 ℃ in a heatable and coolable glass flask with stirrer device and dropping funnel. To the molten diisocyanate, first 30mg of catalyst A and then a mixture of 113.22g (0.028mol) of polyether B and 39.08g (0.091mol) of polyether E, which had been dehydrated beforehand at 100 ℃ and under a vacuum of 15mbar, were added with stirring, these additions being carried out such that the temperature at 50 ℃ did not rise. After the polyether had been completely added, the reaction mixture was heated to 60 ℃ and stirred further at this temperature until a constant NCO content of 2.84% (theory: 3.0%) was reached after a reaction time of 4 hours. The catalyst was then deactivated by addition of 40mg of benzoyl chloride and the product was partitioned. The NCO content of the final product was 2.84%.

Example 13:

37.74g (0.151mol) of pure 2, 4 '-MDI (2, 4' isomer content > 97.5%) are melted at a temperature of 70 ℃ in a heatable and coolable glass flask with stirrer device and dropping funnel. To the molten diisocyanate, first 30mg of catalyst B and then 162.26g (0.084mol) of polyether F were added with stirring, which were dehydrated beforehand at 100 ℃ and under a vacuum of 15mbar, these additions being carried out such that the temperature at 70 ℃ did not rise. After the polyether had been completely added, the reaction mixture was stirred further at 70 ℃ until a constant NCO content of 2.79% (theory: 2.82%) was reached after a reaction time of 1 hour. The catalyst was then deactivated by addition of 60mg of benzoyl chloride and the product was partitioned. The NCO content of the final product was 2.79%.

Example 14:

37.74g (0.151mol) of pure 2, 4 '-MDI (2, 4' isomer content > 97.5%) are melted at a temperature of 70 ℃ in a heatable and coolable glass flask with stirrer device and dropping funnel. To the molten diisocyanate, first 30mg of catalyst A and then 162.26g (0.084mol) of polyether F were added with stirring, which were dehydrated beforehand at 100 ℃ and under a vacuum of 15mbar, these additions being carried out such that the temperature at 70 ℃ did not rise. After the polyether had been completely added, the reaction mixture was stirred further at 70 ℃ until a constant NCO content of 2.78% (theory: 2.82%) was reached after a reaction time of 1.5 hours. The catalyst was then deactivated by addition of 60mg of benzoyl chloride and the product was partitioned. The NCO content of the final product was 2.78%.

Comparative example 1:

36.68g (0.147mol) of pure 2, 4 '-MDI (2, 4' isomer content > 97.5%) are melted at a temperature of 50 ℃ in a heatable and coolable glass flask with stirrer device and dropping funnel. To the molten diisocyanate 163.32g (0.082mol) of polyether C were added with stirring, which had been dehydrated beforehand at 100 ℃ and under a vacuum of 15mbar, the addition being carried out such that the temperature at 50 ℃ did not rise. After the polyether had been completely added, the reaction mixture was heated to 60 ℃ and stirred further at this temperature until a constant NCO content of 2.73% (theory: 2.74%) was reached after a reaction time of 32 hours. After which the product was partitioned. The NCO content of the final product was 2.73%.

Comparative example 2:

36.68g (0.147mol) of pure 2, 4 '-MDI (2, 4' isomer content > 97.5%) are melted at a temperature of 50 ℃ in a heatable and coolable glass flask with stirrer device and dropping funnel. To the molten diisocyanate, first 20mg of catalyst C and then 163.32g (0.082mol) of polyether C were added with stirring, which had been dehydrated beforehand at 100 ℃ and under a vacuum of 15mbar, these additions being carried out such that the temperature at 50 ℃ did not rise. After the polyether had been completely added, the reaction mixture was heated to 60 ℃ and stirred further at this temperature until a constant NCO content of 2.72% (theory: 2.74%) was reached after a reaction time of 5 hours. The catalyst was then deactivated by addition of 30mg of benzoylammonia and the product was partitioned. The NCO content of the final product was 2.72%.

Comparative example 3:

20.26g (0.081mol) of pure 2, 4 '-MDI (2, 4' isomer content > 97.5%) are melted at a temperature of 50 ℃ in a heatable and coolable glass flask with stirrer device and dropping funnel. To the molten diisocyanate 179.74g (0.045mol) of polyether B were added with stirring, which was previously dehydrated at 100 ℃ and under a vacuum of 15mbar, the addition being carried out such that the temperature at 50 ℃ did not rise. After the polyether had been completely added, the reaction mixture was heated to 60 ℃ and stirred further at this temperature until a constant NCO content of 1.49% (theoretical: 1.51%) was reached after a reaction time of 60 hours. After which the product was partitioned. The NCO content of the final product was 1.49%.

Comparative example 4:

20.26g (0.081mol) of pure 2, 4 '-MDI (2, 4' isomer content > 97.5%) are melted at a temperature of 50 ℃ in a heatable and coolable glass flask with stirrer device and dropping funnel. To the molten diisocyanate, first 20mg of catalyst C and then 179.74g (0.045mol) of polyether C were added with stirring, which were dehydrated beforehand at 100 ℃ and under a vacuum of 15mbar, these additions being carried out such that the temperature at 50 ℃ did not rise. After the polyether had been completely added, the reaction mixture was heated to 60 ℃ and stirred further at this temperature until a constant NCO content of 1.37% (theory: 1.51%) was reached after a reaction time of 4 hours. The catalyst was then deactivated by addition of 30mg of benzoyl chloride and the product was partitioned. The NCO content of the final product was 1.37%.

Comparative example 5:

37.74g (0.151mol) of pure 2, 4 '-MDI (2, 4' isomer content > 97.5%) are melted at a temperature of 70 ℃ in a heatable and coolable glass flask with stirrer device and dropping funnel. To the molten diisocyanate 162.26g (0.084mol) of polyether F were added with stirring, which was dehydrated beforehand at 100 ℃ and under a vacuum of 15mbar, the addition being carried out such that the temperature at 70 ℃ did not rise. After the polyether had been completely added, the reaction mixture was stirred further at 70 ℃ until a constant NCO content of 2.82% (theory: 2.82%) was reached after a reaction time of 7.5 hours. After which the product was partitioned. The NCO content of the final product was 2.82%.

Table 4: residual monomer content and viscosity for examples 4-12 and comparative examples 1-4

Examples	Residual monomer [ wt.%]	Viscosity [ mPas ] at 25 ℃]	Viscosity [ mPas ] at 100 ℃]
				4	＜0.05	16000	425
5	0.1	17900	410
				6	＜0.1	19750	648
7	＜0.1	20700	598
				8	0.1	13900	269
9	0.1	12700	227
				10	0.2	16200	315
11	0.2	Not detected	672
				12	＜0.05	81800	557
C1	0.9	18450	333
				C2	0.3	16390	410
C3	0.5	15900	521
				C4	＜0.05	18425	445

Table 5: residual monomer content and viscosity for examples 13-14 and comparative example 5

Examples	Residual monomer [ wt.%]	Viscosity [ mPas ] at 100 ℃]
			13	0.9	1830
14	1.0	1740
			C5	1.7	2760

It is clear from the examples of the invention and the comparative examples that by using the catalyst of the invention, a reactive polyurethane prepolymer having both a significantly reduced residual monomer content and a significantly reduced viscosity is successfully prepared and that a tin-containing catalyst may not be used.

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.

Claims (3)

1. A process for preparing NCO-functional polyurethane prepolymers having an NCO content of 0.2 to 12% by weight, wherein

A) At least one monomeric asymmetric diisocyanate having a molecular weight of 160g/mol to 500g/mol and

B) at least one polyether polyol and/or polyester polyol

C) Reacting with each other in the presence of a zirconium (IV) acetylacetonate complex in a ratio of isocyanate groups to hydroxyl groups of from 1.05: 1 to 2.0: 1, at least one of the acetylacetone ligands present in the catalyst bearing a fluorine substituent.

2. The process according to claim 1, wherein the asymmetric diisocyanate in component A) is selected from the group consisting of 2, 4-tolylene diisocyanate (2, 4-TDI), diphenylmethane 2, 4 '-diisocyanate (2, 4' -MDI), 1-isocyanatomethyl-3-isocyanato-1, 5, 5-trimethylcyclohexane (isophorone diisocyanate, IPDI) or mixtures thereof.

3. A process as claimed in claim 1, wherein in C) use is made of zirconium (IV) acetylacetonate complexes with exclusively in each case at least one CF₃The radical acetylacetonate ligand acts as a ligand.