DE102009058463A1 - Polyisocyanate mixture, useful e.g. in coating, comprises two various aromatic polyisocyanate mixtures based on diphenylmethane diisocyanate, polyether based on propylene oxide and amino group containing polyether based on propylene oxide - Google Patents

Abstract

Polyisocyanate mixture (I) made of diphenylmethane diisocyanate with 2 aromatic rings, polymer-diphenylmethane diisocyanate with 3 or more aromatic rings and an isocyanate-functional polyurethane, comprises: (a) at least an aromatic polyisocyanate mixture based on diphenylmethane diisocyanate; (b) at least an aromatic polyisocyanate mixture based on diphenylmethane diisocyanate; (c) at least an amino group free polyether based on propylene oxide; and/or (d) at least an amino group containing polyether based on propylene oxide. Polyisocyanate mixture (I) made of 1-15 wt.% of diphenylmethane diisocyanate with 2 aromatic rings, 20-50 wt.% of polymer-diphenylmethane diisocyanate with 3 or more aromatic rings and 40-75 wt.% of an isocyanate-functional polyurethane, comprises: (a) at least an aromatic polyisocyanate mixture based on diphenylmethane diisocyanate with at least 98% of isocyanate groups in 2,4'-positions, 0 to maximum 1% in 4,4'-positions and 0 to maximum 1% in 2,2'-positions, an isocyanate content of greater than 33 wt.% and a functionality of 2; (b) at least an aromatic polyisocyanate mixture based on diphenylmethane diisocyanate with less than 50% of 4,4'-isomers, 1-15% of 2,4'-isomers and 0.1-5% of 2,2'-isomers, an isocyanate content of 30-33 wt.% and a functionality of greater than 2.4; (c) at least an amino group free polyether based on propylene oxide with a hydroxyl number of 5-225 mg of potassium hydroxide (KOH)/g, and a functionality of at least 2; and/or (d) at least an amino group containing polyether based on propylene oxide with a hydroxyl number of 40-625 mg KOH/g, a functionality of at least 2 and an amine content of 0.25-7.75 wt.%, where (I) has an isocyanate content of 12-20 wt.%, isocyanate functionality of less than 2.4, a viscosity of less than 15000 mPa at 23[deg] C and a shear rate of 40 l/s. Independent claims are included for a process for preparing (I) comprising producing an isocyanate group containing polyurethane from the components (a), (c) and/or (d) and mixing the reaction product with (b), where an urethane group of isocyanate group containing polyurethane is allophanatized with an excess of (a), before the mixing with (b).

Description

The invention relates to novel polyisocyanate mixtures, their preparation by reacting 2,4'-diphenylmethane diisocyanate with polyetherol mixtures and other aromatic polyisocyanates and their use as isocyanate component for the production of moisture-curing coating, sealing and adhesives.

Moisture-curing adhesives and their preparation belong to the general state of the art and have been described many times in the literature. All prepolymers containing isocyanate groups, which are not stored under complete exclusion of moisture, lose isocyanate groups over time due to reaction with atmospheric moisture. Temperature stress promotes this process significantly. On the surface, this reaction proceeds rapidly, the diffusion into the interior of z. As moldings, foams or adhesive and sealant layers can take long periods. As long as this reaction takes place, the molecular weight or the crosslinking density increases, correspondingly, the physical properties change.

In particular in the field of adhesives, the fastest possible complete conversion of the free isocyanate groups of the prepolymer with atmospheric moisture is desirable in order to obtain the ready-to-use properties at an early stage. Nevertheless, a very good shelf life of the prepolymer must be given. Another important requirement is the heat resistance of the bonds, which is particularly required in structural wood bonding in the USA. To accelerate the curing process, the formulations are often external catalysts such. As organic tin compounds (dibutyltin dilaurate) or aminic accelerator (Dimorpholinodiethylether) added. However, these catalysts can adversely affect the storage stability under temperature load, in particular of prepolymers based on reactive aromatic isocyanates, as well as the property profile of the adhesive. There has therefore been no lack of attempts to provide isocyanate-containing prepolymers high reactivity, which have a high reactivity to moisture without the addition of external catalysts. Such prepolymers are often based on polyether or polyester polyols containing nitrogen atoms. These products are preferably used in one-part, moisture-curing foam applications. Further, many attempts have been made to improve the heat resistance of adhesions by organic and inorganic additives in the adhesive formulation, however, there is a need for new adhesive binders having significantly improved heat resistance to have higher degrees of freedom in adhesive formulation.

In the EP-A 0 002 768 For example, one-component foams containing prepolymers containing isocyanate group-containing prepolymers are described. These prepolymers are prepared by reacting a polyol mixture consisting of 90-100 wt .-% of an aminopolyether and / or polyester alcohol, with organic polyisocyanates and other additives, such. B. propellants in pressure vessels, such. As aerosol cans obtained. When relaxing to atmospheric pressure, with the help of z. As a valve foams the mixture and cured quickly under the influence of humidity to a dimensionally stable closed-cell polyurethane foam. However, such products are not suitable for the formulation of moisture-curing adhesives.

The DE-A 4 417 938 describes isocyanate group-containing prepolymers prepared from organic polyisocyanates and polyols, some of these polyols being based on aromatic aminopolyether polyols. Such prepolymers in particular exhibit a reduced tendency to crystallize and are suitable for the production of cellular or compact polyurethane plastics. For the production of adhesives such products are not suitable.

The EP-A 1 471 088 describes PU formulations based on polyisocyanates and polyether polyols with at least one aromatic and / or aliphatic NH ₂ - or NHR-group-containing initiator, which immediately or very quickly lead to good compatibility on mixing the polyol component with the polyisocyanates, so that the stirring time can be shortened in comparison with systems of the prior art. This good compatibility is particularly desirable in the production of PUR cast resins and potting compounds for moldings, which are prepared by curing in a mold prepared with release agent.

The DE-A 1 922 626 describes a process for preparing storage-stable, moisture-fast one-component polyurethane-based one-component systems. The polyurethane isocyanates based on amine-initiated polyethers obtainable by this process according to the Offenbahrungen and examples are in considerable amounts of suitable paint solvents (60 wt .-% solvent, 40 wt .-% polymer), such as esters, ketones or chlorinated hydrocarbons, and are useful as binders in one-component paint systems. Suitable solvent-free, low-viscosity one-component adhesives can not be produced by this process.

The WO1995 / 0010555 describes moisture-curing adhesive compositions consisting of the reaction product of a polyisocyanate and an isocyanate-reactive component containing at least one aliphatic amine-initiated polyol having an ethylene oxide content of at least 1%. Isocyanate-containing prepolymers based on polyethers with ethylene oxide units have a particularly high affinity for moisture. This can lead to increased blistering during the curing of the adhesives. This blistering is detrimental to the adhesion bond.

The from the WO 2009/124680 Although known prepolymers have a fast drying and formulated on the basis of these prepolymers adhesives acceptable strengths, the heat resistance of the resulting adhesive films but not yet meet the high demands of many users.

The DE-A 10 237 649 describes a 1K polyurethane adhesive containing at least one polyisocyanate prepolymer and at least one aminopolyether polyol wherein the molar ratio of ether groups to amine nitrogen in the aminoether polyol is 7 to 30. The proportion of aminopolyetherpolyols in the adhesive according to the invention is very low and amounts to only 0.2 to 4.0% by weight. This small proportion leads under Dimorpholinodiethyletherkatalyse already to a halving of the pressing time in the bonding of beech wood. However, the open time (that is, the processing time) is already significantly adversely affected by this small amount of aminopolyether.

The DE-A 10 304 153 describes a polyurethane prepolymer having as structural components a mixture of polyisocyanates having symmetrical and asymmetric isocyanate groups and a mixture of polyethers having functionalities <2.5 and> 2.5, wherein the proportion of polyisocyanates having symmetrical isocyanate groups is higher than that of polyisocyanates with asymmetric polyisocyanates. The inventive value of this patent application is that the claimed prepolymers are particularly bright. This issue is highly doubtful because the color of prepolymers does not depend on the isomer composition of polyisocyanates nor on the functionality of polyol components. This fact was confirmed when the relevant patent was granted EP-B 1 490 418 At least the molecular weights of the polyether components were severely limited.

The EP-A 1 072 620 describes a low-solvent adhesive composition consisting of up to 99.999 wt .-% of an isocyanate prepolymer, 0 to 20 wt .-% additives and excipients and 0.001 to 10 wt .-% of at least one morpholine derivative as an activator. The composition of the claimed prepolymer is chosen to be very broad, thus there are no specific properties of the resulting adhesive compositions. Furthermore, a morpholine derivative is absolutely necessary, which has a limiting effect, adversely affect the storage stability and can lead to compatibility problems. The EP-A 1 072 621 describes fibrous adhesive compositions based on the adhesive composition according to the EP-A 1 072 620 and 0.1 to 20 wt .-% of a filler containing at least one fiber, with the difference that no morpholine derivative, but a fiber-containing filler is absolutely necessary.

The object of the present invention was to provide novel polyisocyanate mixtures for adhesive applications which do not have the disadvantages of the prior art. They should have a low viscosity, improved storage stability, and without the addition of a separate activator fast film formation and a short film drying time, a high initial strength after a short sticking time and a high final strength after the shortest possible curing time and high heat resistance of the resulting bond.

This problem could be solved by providing the polyisocyanate mixtures according to the invention.

• A) 1 bis 15 Gew.-% Diphenylmethandiisocyanat mit 2 aromatischen Ringen
• B) 20 bis 50 Gew.-% Polymer-Diphenylmethandiisocyanat mit 3 und mehr aromatischen Ringen und
• C) 40 bis 75 Gew.-% eines isocyanatfunktionellen Polyurethans,

dadurch gekennzeichnet, dass die Polyisocyanatgemische Isocyanatgehalte von 12 bis 20 Gew.-%, Isocyanatfunktionalitäten von > 2,5, Viskositäten von < 10.000 mPa·s bei 23°C und einer Scherrate von 40 l/s aufweisen und dass sie enthalten:

• a) mindestens ein aromatisches Polyisocyanatgemisch auf Basis von Diphenylmethandiisocyanat mit mindestens 98,0% Isocyanatgruppen in 2,4'-Stellung; zwischen 0,0 und maximal 1,0% in 4,4'-Stellung und zwischen 0,0 bis maximal 1,0% in 2,2'-Stellung, einem Isocyanatgehalt von > 33 Gew.-% und einer Funktionalität von 2,0,
• b) mindestens ein aromatisches Polyisocyanatgemisch auf Basis von Diphenylmethandiisocyanat mit einem Anteil an 4,4'-Isomeren von < 50%, einem Anteil an 2,4'-Isomeren im Bereich von 1 bis 15% und einem Anteil von 2,2'-Isomeren im Bereich von 0,1 bis 5%, einem Isocyanatgehalt zwischen 30 und 33 Gew.-% und einer Funktionalität > 2,4,

sowie die Reaktionsprodukte (C) derselben mit

• c) mindestens einen aminogruppenfreien Polyether auf Basis von Propylenoxid mit einer OH-Zahl im Bereich von 5 bis 225 mg KOH/g, einer Funktionalität von mindestens 2,0 und/oder
• d) mindestens einen aminogruppenhaltigen Polyether auf Basis von Propylenoxid mit einer OH-Zahl im Bereich von 40 bis 625 mg KOH/g, einer Funktionalität von mindestens 2,0 und einem Amingehalt im Bereich von 0,25 bis 7,75 Gew.-%.

The invention therefore polyisocyanate mixtures consisting of

• A) 1 to 15 wt .-% diphenylmethane diisocyanate with 2 aromatic rings
• B) 20 to 50 wt .-% polymer diphenylmethane diisocyanate having 3 and more aromatic rings and
• C) 40 to 75% by weight of an isocyanate-functional polyurethane,

characterized in that the polyisocyanate mixtures have isocyanate contents of 12 to 20 wt .-%, isocyanate functionalities of> 2.5, viscosities of <10,000 mPa · s at 23 ° C and a shear rate of 40 l / s and that they contain:

• a) at least one aromatic polyisocyanate mixture based on diphenylmethane diisocyanate having at least 98.0% isocyanate groups in the 2,4'-position; between 0.0 and a maximum of 1.0% in the 4,4'-position and between 0.0 to a maximum of 1.0% in the 2,2'-position, an isocyanate content of> 33 wt .-% and a functionality of 2 , 0,
• b) at least one aromatic polyisocyanate mixture based on diphenylmethane diisocyanate having a proportion of 4,4'-isomers of <50%, a proportion of 2,4'-isomers in the range of 1 to 15% and a proportion of 2,2'-isomers Isomers in the range of 0.1 to 5%, an isocyanate content between 30 and 33 wt .-% and a functionality> 2.4,

and the reaction products (C) of the same with

• c) at least one amino group-free polyether based on propylene oxide having an OH number in the range of 5 to 225 mg KOH / g, a functionality of at least 2.0 and / or
• d) at least one amino group-containing polyether based on propylene oxide having an OH number in the range of 40 to 625 mg KOH / g, a functionality of at least 2.0 and an amine content in the range of 0.25 to 7.75 wt .-% ,

The invention also provides a process for the preparation of the prepolymers of the invention by reaction of specific aromatic polyisocyanate mixtures a) with specific polyetherol mixtures c) and / or d) and subsequent mixing with the aromatic polyisocyanate mixture b) and their use as isocyanate component in moisture-curing adhesives.

The viscosity of the polyisocyanate mixtures according to the invention is 23 ° C. and a shear rate of 40 l / s <15,000 mPa · s, preferably <12,000 mPa · s, more preferably <10,000 mPa · s and most preferably <9,000 mPa · s.

The isocyanate content of the polyisocyanate mixtures according to the invention is in the range of 12 to 20 wt .-%, preferably 13 to 19 wt .-% and particularly preferably in the range of 14 to 18 wt .-%. The average isocyanate functionality of the polyisocyanate mixtures according to the invention is> 2.20, preferably> 2.40 and more preferably> 2.60.

In the preparation of the polyisocyanate mixtures according to the invention, the polyisocyanate component a) is introduced into a reaction vessel and at temperatures in the range from 20 to 120 ° C., preferably from 30 to 110 ° C. and more preferably from 40 to 100 ° C., the polyol components c) and / or d) either alone, as a mixture or added in succession. After the reaction of a) with c) and / or d), the polyisocyanate component b) is added and mixed with the reaction components. The components a) to d) are preferably used in the proportions that the properties of the polyisocyanate mixture described above, in particular the viscosity, the isocyanate content and the functionality are achieved.

The polyisocyanate component a) consists of at least one aromatic polyisocyanate mixture based on diphenylmethane diisocyanate with at least 98.0% isocyanate groups in the 2,4'-position, between 0.0 and at most 1.0% in the 4,4'-position and between 0.0 and a maximum of 1.0% in the 2,2'-position, with a functionality of 2.0. The isocyanate content is> 33.0 wt .-%, preferably> 33.2 wt .-%, more preferably> 33.4 wt .-% and particularly preferably> 33.5 wt .-%.

The polyisocyanate component b) consists of at least one polyisocyanate mixture based on diphenylmethane diisocyanate with a proportion of 4,4'-isomers of <50%, preferably <48%, more preferably <47% and most preferably <46%; a proportion of 2,4'-isomers in the range of 1 to 15%, particularly preferably 2 to 14% and particularly preferably 2.5 to 13%; and a proportion of 2,2'-isomers in the range of 0 to 5%, preferably 0 to 4% and particularly preferably 0 to 3.5%; an isocyanate content between 30 and 33 wt .-%, particularly preferably 31 and 32 wt .-%; and a functionality> 2.0, preferably> 2.2, more preferably> 2.4 and very particularly preferably> 2.5.

The polyol component c) consists of at least one amino group-free polyether based on propylene oxide having an OH number in the range from 5 to 225 mg KOH / g, preferably 6 to 180 and more preferably 8 to 160 and a functionality of at least 2.0, preferably 2.0 to 4.0, more preferably 2.0 to 3.0, and most preferably 2.0 to 2.5. As starter molecules for the polyol component c) For example, polyols, such as. For example, ethylene glycol, propylene glycol, 1,4-butanediol, polyols, such as. As glycerol, trimethylolpropane or pentaerythritol and water into consideration.

The polyol component d) consists of at least one amino group-containing polyether based on propylene oxide having an OH number in the range from 40 to 625 mg KOH / g, preferably 45 to 550 and particularly preferably 50 to 500, a functionality of 2.0 to 4, 0, preferably 3.0 to 4.0, and an amine content in the range of 0.25 to 7.75, preferably 0.56 to 6.90 and particularly preferably 0.62 to 6.25 wt .-%. As starter molecules for the polyol component d), for example, amines, such as. As ethylenediamine, hexamethylenediamine, isophoronediamine, 4,4'-diaminodicyclohexylmethane, triethanolamine, N-methyldiethanolamine, n-hexylamine or cyclohexylamine into consideration.

The polyether polyols used in c) and / or d) can finely dispersed fillers and contain sedimentation-stable. Suitable fillers for the polyethers are, for example, organic fillers based on styrene-acrylonitrile copolymers or polyureas. The organic fillers can advantageously be produced in the presence of the filler-free base polyether in this by chemical reaction. Such a reaction may, for. Example, be a copolymerization of acrylonitrile with styrene in the presence of the polyether as the reaction medium. Another suitable chemical reaction is the reaction of diamines and / or hydrazine with diisocyanates to finely divided urea particles in the presence of the filler-free base polyether as the reaction medium. However, the fillers can also be prepared separately and incorporated with special dispersing using high shear forces in the filler-free base polyether sedimentation stable.

The preparation of the polyisocyanate mixtures according to the invention is expediently carried out by reaction of the isocyanate components a) with the polyol components c) and / or d), resulting in polyurethane mixtures containing isocyanate groups. Preferably, the isocyanate component a) is placed in a reaction vessel under an inert gas atmosphere and the polyol components alone, as a mixture or added in succession. The reaction temperatures are in the range of 20 to 120 ° C, preferably 30 to 110 ° C and particularly preferably 40 to 100 ° C. A possibly occurring exotherm is expediently absorbed by cooling so that the reaction between the isocyanate groups of components a) with the hydroxyl groups of components c) and / or d) proceeds at a constant temperature. The reaction is complete when the desired isocyanate contents or viscosities of the reaction stage are reached. Subsequently, the polyisocyanate component b) is metered into the previously synthesized urethane group-containing polyisocyanate mixture and mixed therewith.

In a particular embodiment, in the preparation of the polyisocyanate mixtures according to the invention after the reaction of the isocyanate components a) with the polyol components c) and / or d) an allophanatization reaction is carried out, excess isocyanate molecules a) being added to the urethane groups of the isocyanate group-containing polyurethanes previously formed. The reaction is complete when the desired isocyanate contents or viscosities of the reaction stage are reached. Subsequently, the polyisocyanate component b) is metered into the previously synthesized allophanate group and optionally urethane group-containing polyisocyanate mixture and mixed with it.

• A) 1 bis 15 Gew.-% Diphenylmethandiisocyanat mit 2 aromatischen Ringen
• B) 20 bis 50 Gew.-% Polymer-Diphenylmethandiisocyanat mit 3 und mehr aromatischen Ringen und
• C) 40 bis 75 Gew.-% eines isocyanatfunktionellen Polyurethans

und haben Isocyanatgehalte von 12 bis 20 Gew.-%, Isocyanatfunktionalitäten von > 2,5 und Viskositäten von < 10.000 mPa·s bei 23°C und bei einer Scherrate von 40 l/s.The polyisocyanate mixtures according to the invention consisting of

• A) 1 to 15 wt .-% diphenylmethane diisocyanate with 2 aromatic rings
• B) 20 to 50 wt .-% polymer diphenylmethane diisocyanate having 3 and more aromatic rings and
• C) 40 to 75 wt .-% of an isocyanate-functional polyurethane

and have isocyanate contents of 12 to 20 wt .-%, isocyanate functionalities of> 2.5 and viscosities of <10,000 mPa · s at 23 ° C and at a shear rate of 40 l / s.

The resulting polyisocyanate mixtures according to the invention are suitable without further additives especially for use as one-component, moisture-curing coating, adhesives and sealants. However, the combination with polyols, aspartic acid esters and polyamines is possible, which are then two-component systems to be processed. The polyisocyanate mixtures according to the invention are characterized by a rapid drying at room temperature and a very early bond strength, so that catalysts and accelerators can be completely dispensed with. For this reason, the polyisocyanate mixtures have an extremely good storage stability, even at elevated temperatures of up to 80 ° C. Furthermore, the viscosity is in a very favorable for the application area. The viscosity of the polyisocyanate mixtures according to the invention is 25 ° C. and a shear rate of 40 l / s <10,000 mPa · s, preferably <9,000 mPa · s, more preferably <8,000 mPa · s and most preferably <7,000 mPa · s. This is the Applicability given in different climates. The film-forming time of the adhesives prepared from the polyisocyanate mixtures according to the invention is at a layer thickness of 250 microns and climatic conditions of 23 ° C and 50% relative humidity between 30 and 75 min, preferably between 35 and 65 min and more preferably between 40 and 60 min. The film drying time of the adhesives prepared from the polyisocyanate mixtures according to the invention is at a layer thickness of 250 microns and climatic conditions of 23 ° C and 50% relative humidity at <100 min, preferably at <90 min and more preferably <80 min. The polyisocyanate mixtures according to the invention not only provide adhesives of rapid drying and high bond strength, but the bonds also have a significantly higher temperature resistance than adhesives of the prior art, which is clearly demonstrated by DTA measurements.

The invention will now be illustrated by the following non-limiting examples:

Example 1:

452.0 g of a Polypropylenoxidpolyethers based on 1,2-diaminoethane having an OH number of 60 mg KOH / g are placed in a 1 liter four-necked flask and stirred for 1 hour at 120 ° C under a vacuum of 20 mbar. It is then cooled to 70 ° C. The resulting polyol mixture is added within about 30 minutes to a mixture of 207.8 g of 2,4'-diphenylmethane diisocyanate (MDI) with an NCO content of 33.6% by weight and 0.1 g of dibutyltin dilaurate at 80.degree , It is stirred at 80 ° C until the isocyanate content is about 7.5% or constant. It is then cooled to 60 ° C and 340 g of a polyisocyanate based on MDI with an NCO content of 31.5 wt .-%, a content of 2,2'-MDI of 0.16%, a content of 2.4 '-MDI of 4.21% and a content of 4,4'-MDI of 39.2%, and a viscosity of 200 mPa · s (25 ° C) added. The mixture is then stirred at 60 ° C for 30 minutes. The result is a brownish colored polyisocyanate mixture having an NCO content of 15.3 wt .-%, a viscosity of 6,740 mPa · s (23 ° C, shear rate 40 l / s) and an average isocyanate functionality of about 2.65.

Example 2:

A mixture of 227.0 g of a polypropylene oxide polyether based on 1,2-propanediol having an OH number of 56 mg KOH / g and 227.0 g of a polypropylene oxide polyether based on 1,2-diaminoethane having an OH number of 60 mg KOH / g is placed in a 1 liter four-necked flask and stirred for 1 hour at 120 ° C under a vacuum of 20 mbar. It is then cooled to 70 ° C. The resulting polyol mixture is added within about 30 minutes to a mixture of 206.0 g of 2,4'-diphenylmethane diisocyanate (MDI) with an NCO content of 33.6% by weight and 0.1 g of dibutyltin dilaurate at 80.degree , It is stirred at 80 ° C until the isocyanate content is about 7.5% or constant. It is then cooled to 60 ° C and 340 g of a polyisocyanate based on MDI with an NCO content of 31.5 wt .-%, a content of 2,2'-MDI of 0.16%, a content of 2.4 '-MDI of 4.21% and a content of 4,4'-MDI of 39.2%, and a viscosity of 200 mPa · s (25 ° C) added. The mixture is then stirred at 60 ° C for 30 minutes. The result is a brownish colored polyisocyanate mixture having an NCO content of 15.4 wt .-%, a viscosity of 3840 mPa · s (23 ° C, shear rate 40 l / s) and an average isocyanate functionality of about 2.46.

Example 3:

450.4 g of a Polypropylenoxidpolyethers based on 1,2-diaminoethane having an OH number of 60 mg KOH / g are placed in a 1 liter four-necked flask and at 120 ° C for 1 hour under stirred a vacuum of 20 mbar. It is then cooled to 70 ° C. The resulting polyol mixture is added within about 30 minutes to a mixture of 148.2 g of 2,4'-diphenylmethane diisocyanate (MDI) with an NCO content of 33.6% by weight and 0.1 g of dibutyltin dilaurate at 80 ° C. , It is stirred at 80 ° C until the isocyanate content is about 5% or constant. It is then cooled to 60 ° C and 401.4 g of a polyisocyanate based on MDI with an NCO content of 31.5 wt .-%, a content of 2,2'-MDI of 0.16%, a content of 2 , 4'-MDI of 4.21% and a content of 4,4'-MDI of 39.2%, and a viscosity of 200 mPa · s (25 ° C) added. The mixture is then stirred at 60 ° C for 30 minutes. The result is a brownish colored polyisocyanate mixture having an NCO content of 15.2 wt .-%, a viscosity of 9,950 mPa · s (23 ° C, shear rate 40 l / s) and an average isocyanate functionality of about 2.97.

Example 4:

A mixture of 225.86 g of a polypropylene oxide polyether based on 1,2-propanediol having an OH number of 56 mg KOH / g and 225.86 g of a polypropylene oxide polyether based on 1,2-diaminoethane having an OH number of 60 mg KOH / g is placed in a 1 liter four-necked flask and stirred for 1 hour at 120 ° C under a vacuum of 20 mbar. It is then cooled to 70 ° C. The resulting polyol mixture is added over about 30 minutes to a mixture of 207.48 g of 2,4'-diphenylmethane diisocyanate (MDI) having an NCO content of 33.6% by weight and 0.1 g of dibutyltin dilaurate at 80 ° C. , It is stirred at 80 ° C until the isocyanate content is about 7.5% or constant. It is then cooled to 60 ° C and 340.79 g of a polyisocyanate based on MDI having an NCO content of 31.25 wt .-%, a content of 2,2'-MDI of 0.1%, a content of 2 , 4'-MDI of 3.1% and a content of 4,4'-MDI of 27.8%, and a viscosity of 680 mPa · s (25 ° C) added. The mixture is then stirred at 60 ° C for 30 minutes. The result is a brownish colored polyisocyanate mixture having an NCO content of 15.2 wt .-%, a viscosity of 5,270 mPa · s (23 ° C, shear rate 40 l / s) and an average isocyanate functionality of about 2.55.

Example 5:

338.1 g of a polypropylene oxide polyether based on triethanolamine having an OH number of 145 mg KOH / g are placed in a 1 liter four-necked flask and stirred for 1 hour at 120 ° C under a vacuum of 20 mbar. It is then cooled to 70 ° C. The resulting polyol mixture is added within about 30 minutes to a mixture of 299.4 g of 2,4'-diphenylmethane diisocyanate (MDI) with an NCO content of 33.6% by weight and 0.1 g of dibutyltin dilaurate at 80.degree , It is stirred at 80 ° C until the isocyanate content is about 7.5% or constant. It is then cooled to 60 ° C and 362.5 g of a polyisocyanate based on MDI having an NCO content of 31.5 wt .-%, a content of 2,2'-MDI of 0.16%, a content of 2 , 4'-MDI of 4.21% and a content of 4,4'-MDI of 39.2%, and a viscosity of 200 mPa · s (25 ° C) added. The mixture is then stirred at 60 ° C for 30 minutes. The result is a brownish colored polyisocyanate mixture having an NCO content of 17.6 wt .-%, a viscosity of 9,200 mPa · s (23 ° C, shear rate 40 l / s) and an average isocyanate functionality of about 2.63.

Example 6:

504.9 g of a polypropylene oxide polyether based on glycerol, which still contains 20 wt .-% of a reaction product of hydrazine hydrate and a mixture of isomers of 2,6- and 2,6-toluene diisocyanate (weight ratio 8: 2) finely dispersed, with a OH number of 28.5 mg KOH / g are placed in a 1 liter four-necked flask and stirred for 1 hour at 120 ° C under a vacuum of 20 mbar. It is then cooled to 70 ° C. The resulting polyol mixture is added within about 30 minutes to a mixture of 125.3 g of 2,4'-diphenylmethane diisocyanate (MDI) having an NCO content of 33.6% by weight and 0.1 g of dibutyltin dilaurate at 80.degree , It is stirred at 80 ° C until the isocyanate content is about 5% or constant. It is then cooled to 60 ° C and 369.8 g of a polyisocyanate based on MDI with an NCO content of 31.5 wt .-%, a content of 2,2'-MDI of 0.16%, a content of 2 , 4'-MDI of 4.21% and a content of 4,4'-MDI of 39.2%, and a viscosity of 200 mPa · s (25 ° C) added. The mixture is then stirred at 60 ° C for 30 minutes. The result is a beige / brownish colored polyisocyanate mixture having an NCO content of 14.5 wt .-%, a viscosity of 5,990 mPa · s (23 ° C, shear rate 40 l / s) and an average isocyanate functionality of about 2.50 ,

Example 7:

A mixture of 172.8 g of a polypropylene oxide polyether based on 1,2-propanediol having an OH number of 56 mg KOH / g and 129.6 g of a polypropylene oxide polyether based on 1,2-diaminoethane having an OH number of 60 mg KOH / g and 129.6 g of a polypropylene oxide polyether based on triethanolamine with a OH number of 145 mg KOH / g is presented in a 1 liter four-necked flask and stirred for 1 hour at 120 ° C under a vacuum of 20 mbar. It is then cooled to 70 ° C. The resulting polyol mixture is metered in over about 30 minutes to a mixture of 228.0 g of 2,4'-diphenylmethane diisocyanate (MDI) having an NCO content of 33.6% by weight and 0.1 g of dibutyltin dilaurate at 80.degree , It is stirred at 80 ° C until the isocyanate content is about 7.5% or constant. It is then cooled to 60 ° C and 340.0 g of a polyisocyanate based on MDI with an NCO content of 31.5 wt .-%, a content of 2,2'-MDI of 0.16%, a content of 2 , 4'-MDI of 4.21% and a content of 4,4'-MDI of 39.2%, and a viscosity of 200 mPa · s (25 ° C) added. The mixture is then stirred at 60 ° C for 30 minutes. The result is a brownish colored polyisocyanate mixture having an NCO content of 15.2 wt .-%, a viscosity of 6,800 mPa · s (23 ° C, shear rate 40 l / s) and an average isocyanate functionality of about 2.55.

Example 8:

A mixture of 521 g of a polypropylene oxide polyether based on 1,2-propanediol having an OH number of 14 mg KOH / g and 521 g of a polypropylene oxide polyether based on triethanolamine having an OH number of 145 mg KOH / g is dissolved in a 2 liter Presented four-necked flask and stirred for 1 hour at 120 ° C under a vacuum of 20 mbar. It is then cooled to 70 ° C. The resulting polyol mixture is added within about 30 minutes of a mixture of 593 g of 2,4'-diphenylmethane diisocyanate (MDI) with an NCO content of 33.6 wt .-% and 0.25 g of dibutyltin dilaurate at 80 ° C. It is stirred at 80 ° C until the isocyanate content is about 8.4% or is constant. It is then cooled to 60 ° C and 865 g of a polyisocyanate based on MDI with an NCO content of 31.25 wt .-%, a content of 2,2'-MDI of 0.1%, a content of 2.4 'MDI of 3.1% and a content of 4,4'-MDI of 27.8%, and a viscosity of 680 mPa · s (25 ° C) added. The mixture is then stirred at 60 ° C for 30 minutes. The result is a brownish colored polyisocyanate mixture having an NCO content of 16.1 wt .-%, a viscosity of 8,700 mPa · s (23 ° C, shear rate 40 l / s) and an average isocyanate functionality of about 2.75.

Example 9:

A mixture of 462 g of a polypropylene oxide polyether based on 1,2-propanediol having an OH number of 14 mg KOH / g and 462 g of a polypropylene oxide polyether based on triethanolamine having an OH number of 145 mg KOH / g is dissolved in a 2 liter Presented four-necked flask and stirred for 1 hour at 120 ° C under a vacuum of 20 mbar. It is then cooled to 70 ° C. The resulting polyol mixture is added within about 30 minutes to a mixture of 526 g of 2,4'-diphenylmethane diisocyanate (MDI) having an NCO content of 33.6% by weight and 0.25 g of dibutyltin dilaurate at 80 ° C. It is stirred at 80 ° C until the isocyanate content is about 8.4% or is constant. Thereafter, 0.25 g of zinc acetylacetonate are added and heated to 100 ° C. It is stirred at 100 ° C until the NCO content is about 6.1% or constant. It is then cooled to 60 ° C and 1050 g of a polyisocyanate based on MDI having an NCO content of 31.25 wt .-%, a content of 2,2'-MDI of 0.1%, a content of 2.4 'MDI of 3.1% and a content of 4,4'-MDI of 27.8%, and a viscosity of 680 mPa · s (25 ° C) added. The mixture is then stirred at 60 ° C for 30 minutes. The result is a brownish colored polyisocyanate mixture having an NCO content of 16.5 wt .-%, a viscosity of 6,300 mPa · s (23 ° C, shear rate 40 l / s) and an average isocyanate functionality of about 3.61.

As comparative examples not according to the invention the following example is given:

Example 10: (Comparison)

A mixture of 430 g of a polypropylene oxide polyether based on 1,2-propanediol having an OH number of 56 mg KOH / g and 430 g of a polypropylene oxide polyether based on 1,2-diaminoethane having an OH number of 60 mg KOH / g placed in a 3 liter four-necked flask and stirred for 1 hour at 120 ° C under a vacuum of 20 mbar. It is then cooled to 70 ° C. The resulting polyol mixture is within about 30 minutes of a mixture of 1140 g of a polyisocyanate based on diphenylmethane diisocyanate (MDI) with an NCO content of 31.5 wt .-%, a content of 2,2'-MDI of 2.3 Wt .-%, a content of 2,4'-MDI of 12.6 wt .-% and a content of 4,4'-MDI of 42.4 wt .-%, and a viscosity of 90 mPa · s at 25 ° C added. Then, using a possibly occurring exothermic reaction to 80 ° C is heated. It is stirred at 80 ° C until the isocyanate content is constant. The result is a brownish colored polyisocyanate mixture having an NCO content of 16.3 wt .-%, a viscosity of 5,400 mPa · s (25 ° C, shear rate 40 l / s) and an average isocyanate functionality of about 2.8.

Application testing:

As a comparison of the reactivity, the film formation time (FBZ, dry-hard time) and film drying times (FTZ, set-to-touch time) were detected ASTM D 5895 in the linear drying recorder and the viscosity at 25 ° C and a shear rate of 40 l / s (rotary viscometer with coaxial cylinders, DIN 53019 ). Further, the storage stability at 70 ° C was measured in terms of viscosity increase over time. The polyisocyanate mixture is said to be storage stable when the viscosity has less than doubled within 14 days of storage at 70 ° C. Example no. Viscosity [mPa.s] (25 ° C, shear rate 40 l / s) FBZ [min] FTZ [min] Storage stable within 14d at 70 ° C According to the invention 1 6740 37 49 Yes Yes 2 3840 58 83 Yes Yes 3 9950 27 47 Yes Yes 5 9200 3 14 Yes Yes 7 6800 24 33 Yes Yes 8th 8700 15 24 Yes Yes 10 5400 51 92 Yes No

The tested inventive polyisocyanate mixtures according to Examples 1 to 3 and 5 to 8 have a low viscosity of <10,000 mPa · s at 23 ° C and a shear rate of 40 l / s, good storage stability and high reactivity, resulting in short film formation and film drying times. The polyisocyanate mixture from Example 10 (comparison) also has a low viscosity and good storage stability, but the film drying time is significantly longer than in the polyisocyanate mixtures according to the invention. Although the polyisocyanate 2 of the invention has similar fast drying times as the comparative product 10, but the viscosity of the polyisocyanate 2 is significantly lower, which is a clear advantage.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 0002768A [0004]
• DE 4417938 A [0005]
• EP 1471088A [0006]
• DE 1922626 A [0007]
• WO 1995/0010555 [0008]
• WO 2009/124680 [0009]
• DE 10237649 A [0010]
• DE 10304153 A [0011]
• EP 1490418 B [0011]
• EP 1072620 A [0012, 0012]
• EP 1072621A [0012]

Cited non-patent literature

• ASTM D 5895 [0041]
• DIN 53019 [0041]

Claims (10)

Polyisocyanate mixtures consisting of: A. 1 to 15 wt .-% diphenylmethane diisocyanate with 2 aromatic rings B. 20 to 50 wt .-% polymer diphenylmethane diisocyanate with 3 and more aromatic rings and C. 40 to 75 wt .-% of an isocyanate-functional polyurethane , characterized in that the polyisocyanate mixtures isocyanate contents of 12 to 20 wt .-%, isocyanate functionalities of> 2.4, viscosities of <15,000 mPa · s at 23 ° C and a shear rate of 40 l / s and that they contain: a ) at least one aromatic polyisocyanate mixture based on diphenylmethane diisocyanate having at least 98.0% isocyanate groups in the 2,4'-position, between 0.0 and at most 1.0% in the 4,4'-position and between 0.0 and a maximum of 1, 0% in 2,2'-position, an isocyanate content of> 33 wt .-% and a functionality of 2.0, b) at least one aromatic polyisocyanate mixture based on diphenylmethane diisocyanate with a proportion of 4,4'-isomers of <50 %, a proportion of 2,4'-isomers in Ber oak of 1 to 15% and a proportion of 2,2'-isomers in the range of 0.1 to 5%, an isocyanate content between 30 and 33 wt .-% and a functionality> 2.4, and the reaction products (C) the same with c) at least one amino group-free polyether based on propylene oxide having an OH number in the range of 5 to 225 mg KOH / g, a functionality of at least 2.0 and / or d) at least one amino group-containing polyether based on propylene oxide with a OH number in the range of 40 to 625 mg KOH / g, a functionality of at least 2.0 and an amine content in the range of 0.25 to 7.75 wt .-%. Polyisocyanate mixtures according to claim 1, characterized in that they have isocyanate contents of 14 to 18 wt .-%, isocyanate functionalities of> 2.5 and viscosities of <10,000 mPa · s at 23 ° C and a shear rate of 40 l / s. Polyisocyanate mixtures according to Claims 1 and 2, characterized in that they have isocyanate contents of 14 to 18 wt .-%, isocyanate functionalities of> 2.5 and viscosities of <8,000 mPa · s at 23 ° C and a shear rate of 40 l / s. A process for the preparation of the polyisocyanate mixtures according to claim 1 to 3, characterized in that initially an isocyanate group-containing polyurethane from the components a), c) and / or d) is prepared and this reaction product is then mixed with the component b). A process for the preparation of the polyisocyanate mixtures according to claim 1 to 3, characterized in that first an isocyanate-containing polyurethane from the components a), c) and / or d) is prepared, then carried out with excess component a) an allophanatization reaction on the urethane groups of the isocyanate group-containing polyurethane and this reaction product is then mixed with the component b). Use of the polyisocyanate mixtures according to claims 1 to 3 for coating, sealant and adhesive applications. Use of the polyisocyanate mixtures according to claims 1 to 3 in moisture-curing coatings, sealants and adhesives. Adhesives containing polyisocyanate mixtures according to claims 1 to 3. With adhesives according to claim 8 coated substrates. Substrates bonded by adhesives according to claim 8.