HK1144696B - Moisture-curing polyisocyanate mixtures - Google Patents

Description

Moisture-curing polyisocyanate mixtures

RELATED APPLICATIONS

This application claims the benefit of german patent application No. 102008052765.3 filed on 22/10/2008, which is hereby incorporated by reference in its entirety for all useful purposes.

Technical Field

The invention relates to moisture-curing polyisocyanate mixtures, to a method for the production thereof and to the use thereof as binders in lacquers (lacquer), coatings, adhesives (adhesive) and sealants (binder).

Background

Moisture-curing prepolymers as constituents of one-component paints have been known for a long time (e.g.H.Kittel, Lehrbuch der Lacke und Beschichthyhtungen, 2, S.Hirzel Verlag, Stuttgart, Leipzig, 1998). Such systems consist of polyurethane prepolymers having free terminal isocyanate groups (NCO groups). After application, crosslinking takes place under the influence of atmospheric moisture to form urea groups.

Prepolymers based on aromatic isocyanates, in particular 2, 4-and optionally 2, 6-Toluene Diisocyanate (TDI), are particularly suitable for quick drying. In particular, polyisocyanates containing isocyanurate groups based on the TDI type are valuable components for the preparation of fast drying polyurethane coatings for wood and furniture applications. Rapid drying is caused by the high degree of crosslinking of these products. This results in a rapid increase in the glass transition temperature during the crosslinking reaction to form urea groups.

However, such fast-drying systems are often brittle due to the high degree of crosslinking, and the films formed from such paints do not have the desired elasticity. Cracks may thus form in the lacquer, especially in the case of significant temperature changes. This is particularly the case for coatings on substrates that undergo significant volume changes, such as wood.

To impart flexibility to such TDI trimers, high molecular weight polyethers are suitable, for example, for synthesizing the prepolymer. As a result of becoming flexible, the polymer generally becomes soft so that the drying speed is significantly reduced. In practice, this means that such moisture-curing coatings based on polyurethane prepolymers dry considerably more slowly than, for example, the widely used nitrocellulose combi paints (NC paints). Long chain polyethers have limited compatibility with TDI isocyanurates, which sometimes (even if only small amounts of polyether) can result in hazy or storage unstable products. The teaching of EP-a 1582543 represents a solution to the above-mentioned problem. It was found in this specification that elastic and simultaneously fast-drying moisture-curing paints can be formulated if solvent-containing preparations comprising NCO-group-containing prepolymers based on TDI trimer and diphenylmethane diisocyanate, at least one of which prepolymers is made using a polyether diol containing ethylene oxide (ethylene oxide) blocks and having a number average molecular weight of from 3000 to 4500 g/mol and an ethylene oxide content of from 2 to 18% by weight, based on all alkylene oxide units present in the diol, are used as isocyanate component.

A disadvantage of coating systems based on EP-a 1582543 is the relatively low solids content of 30 to 35% by weight of the paints formulated therefrom, in particular their poor light and weather resistance, which is manifested in a negative way by a strong tendency to yellowing.

Accordingly, it is an object of the present invention to provide polyisocyanate mixtures with which it is possible to produce paints and coatings which have a drying speed comparable to NC paints, exhibit the desired degree of elasticity and high resistance to solvents and chemicals and do not have the disadvantages of the prior art described above.

In particular, the paints based on the novel products should have a solids content of > 50% by weight and dry equally quickly. The yellowing tendency of the coating is significantly improved compared to the prior art.

It has now been found that polyisocyanate mixtures based on prepolymers based on TDI isocyanurate and specific nitrogen-containing polyethers and aliphatic polyisocyanates can be formulated into moisture-curing (curing-curing) lacquers having a relatively high solids content of > 50% by weight and which can be processed to fast-drying elastomeric coatings having at the same time a high hardness, excellent resistance to solvents and chemicals and good resistance to yellowing under the action of light.

Disclosure of Invention

One embodiment of the present invention is a solvent-containing polyisocyanate mixture having a solvent content of less than 50% by weight, an NCO content of 7 to 15% by weight, a monomeric TDI content of less than 0.2% by weight and a monomeric aliphatic and/or cycloaliphatic isocyanate content of less than 0.2% by weight at an outflow viscosity of 20s at 23 ℃, wherein said mixture consists of:

A) a TDI component comprising a TDI isocyanurate polyisocyanate;

B) an aliphatic and/or alicyclic isocyanate component containing an aliphatic and/or alicyclic polyisocyanate;

and reaction products of at least one of the components A) and/or B) with

C) At least one polyether polyol containing at least one tertiary nitrogen atom having a number average molecular weight of from 500 to 4000 g/mole; and

D) optionally at least one polyether polyol free of nitrogen atoms.

Another embodiment of the present invention is a process for preparing the above solvent-containing polyisocyanate mixtures, wherein

A) A TDI component comprising a TDI isocyanurate polyisocyanate; and

B) aliphatic and/or alicyclic isocyanate component containing aliphatic and/or alicyclic polyisocyanate

By reacting at least one of the two components A) and/or B) with

C) At least one polyether polyol containing at least one tertiary nitrogen atom having a number average molecular weight of from 500 to 4000 g/mole; and

D) optionally at least one polyether polyol free of nitrogen atoms.

Another embodiment of the present invention is the above process, wherein the process is carried out with the concomitant use of a stabilizer and a catalyst.

Another embodiment of the present invention is the above process, wherein a) is used in an amount of 55 to 95% by weight and B) is used in an amount of 5 to 45% by weight, based on the total amount of a) and B).

Another embodiment of the present invention is a coating comprising

a) The above solvent-containing polyisocyanate mixtures;

b) a catalyst to accelerate the reaction of free NCO groups with moisture; and

c) one or more auxiliary substances and additives.

Another embodiment of the present invention is a coating, adhesive and/or sealant comprising the above solvent-containing polyisocyanate mixtures.

Another embodiment of the present invention is an adhesive comprising the above solvent-containing polyisocyanate mixture.

Another embodiment of the present invention is a sealant comprising the above solvent-containing polyisocyanate mixture.

Another embodiment of the invention is a substrate coated with a coating comprising said solvent-containing polyisocyanate mixture.

Detailed Description

The invention accordingly provides solvent-containing polyisocyanate mixtures having a solvent content of < 50% by weight, an NCO content of 7 to 15% by weight, a monomeric TDI content of less than 0.2% by weight, a monomeric aliphatic and/or cycloaliphatic isocyanate content of less than 0.2% by weight (e.g.1, 6-Hexamethylene Diisocyanate (HDI), isophorone diisocyanate (IPDI) and 4, 4' -diisocyanatodicyclohexylmethane) at an outflow viscosity of 20s (DIN4mm beaker, 23 ℃), characterized in that they consist of:

A) TDI components comprising TDI isocyanurate polyisocyanates and

B) an aliphatic and/or alicyclic isocyanate component containing an aliphatic and/or alicyclic polyisocyanate,

and reaction products of at least one of the components A) and B) with

C) At least one polyether polyol containing at least one tertiary nitrogen atom having a number average molecular weight of from 500 to 4000 g/mol, and

D) optionally at least one polyether polyol free of nitrogen atoms.

The invention further provides a process for preparing the solvent-containing polyisocyanate mixtures, in which

A) TDI components comprising TDI isocyanurate polyisocyanates and

B) aliphatic and/or alicyclic isocyanate component containing aliphatic and/or alicyclic polyisocyanate

By reacting at least one of the two components with

C) At least one polyether polyol containing at least one tertiary nitrogen atom having a number average molecular weight of from 500 to 4000 g/mol, and

D) optionally at least one polyether polyol free of nitrogen atoms.

In the preparation of the polyisocyanate mixtures according to the invention, as TDI isocyanurate polyisocyanate A there is generally used an isocyanurate preferably containing 80 to 100% by weight of the 2, 4-isomer and 0 to 20% by weight of the 2, 6-isomer, most particularly preferably 80% by weight of the 2, 4-isomer and 20% by weight of the TDI isomer mixture of the 2, 4-TDI and 2, 6-TDI of the 2, 4-isomer and 2, 6-TDI), these percentages being based on the solvent-free polyisocyanate resin.

The isocyanurate polyisocyanates of TDI may be obtained by catalytic trimerization of the corresponding toluene diisocyanates according to known methods. These are described, for example, in DE-A19523657 and DE-A3928503.

In the preparation of the polyisocyanate mixtures according to the invention, the TDI isocyanurate polyisocyanate in A) is preferably used in the form of an organic solution having an NCO content of 7 to 8.5% by weight, a TDI residual monomer content of < 0.5% by weight and a solids content of 30 to 70% by weight. As the organic solvent, esters such as ethyl acetate, butyl acetate, methoxypropyl acetate, ethylene glycol monomethyl ether acetate, ethyl ethylene glycol acetate, diethylene glycol monomethyl ether acetate; ketones such as methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone; aromatic compounds, such as toluene and xylene, and also high-boiling hydrocarbon mixtures customary in paint chemistry. Esters are preferably used, butyl acetate being particularly preferred.

In the preparation of the polyisocyanate mixtures according to the invention, lacquer polyisocyanates known per se having urethane (urethane), uretdione (uretdione), allophanate, biuret, iminooxadiazinedione and/or isocyanurate groups are generally used as aliphatic and/or cycloaliphatic polyisocyanate component B).

As preferred representatives of component B) there come into consideration the polyisocyanates known per se in paint chemistry which contain urethane, uretdione, allophanate, biuret, iminooxadiazinedione and/or isocyanurate groups and which can be obtained by modifying monomeric aliphatic, cycloaliphatic and/or araliphatic diisocyanates in a manner known to the person skilled in the art. Examples of diisocyanates which may be mentioned include 1, 6-hexamethylene diisocyanate, 1-isocyanato-3, 3, 5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate), 4' -diisocyanatodicyclohexylmethane, 1, 4-diisocyanatocyclohexane, 1-methyl-2, 6-diisocyanatocyclohexane, 4-isocyanatomethyl-1, 8-octane diisocyanate and mixtures thereof.

The preparation of such lacquer polyisocyanates starting from monomeric diisocyanates is known to the person skilled in the art and is described in the following pages, in which relevant references are listed. It is immaterial whether the diisocyanates used are prepared by phosgene or phosgene-free processes.

Lacquer polyisocyanates of the above-mentioned type preferably have an NCO group content of 5 to 25% by weight, an average NCO functionality of 2.0 to 5.0, preferably 2.8 to 4.0 and a residual content of monomeric diisocyanates used for their preparation of less than 1% by weight, preferably less than 0.5% by weight.

Preferred lacquer polyisocyanates of the above-mentioned type are those having free isocyanate groups bonded aliphatically and/or cycloaliphatically.

The lacquer polyisocyanates containing urethane groups are, for example, the reaction products of 1-methyl-2, 4-and optionally 1-methyl-2, 6-diisocyanatocyclohexane with a deficiency of trimethylolpropane or its mixtures with simple diols, for example the isomeric propylene glycols or butanediol. The preparation of such urethane group-containing lacquer polyisocyanates which are virtually free of monomeric forms is described, for example, in DE-A1090196.

Particularly preferred lacquer polyisocyanates are those of the above-mentioned type having a biuret, uretdione, isocyanurate and/or iminooxadiazinedione structure.

Lacquer polyisocyanates containing biuret groups and their preparation are described, for example, in EP-A0003505, DE-A1101394, U.S. Pat. No. 3,983,010 or U.S. Pat. No. 3,3903127.

Paint polyisocyanates containing uretdione groups and isocyanurate groups and their preparation are described, for example, in EP-A0377177.

The isocyanurate group-containing lacquer polyisocyanates include the trimers or mixed trimers of the diisocyanates mentioned above, for example aliphatic, aliphatic/cycloaliphatic and/or cycloaliphatic trimers or mixed trimers based on 1, 6-diisocyanatohexane (diisocyanatonaxane) and/or isophorone diisocyanate, which are obtainable, for example, according to U.S. Pat. No. 4,4324879, U.S. Pat. No. 3, 4288586, DE-A3100262, DE-A3100263, DE-A3033860 or DE-A3144672.

Lacquer polyisocyanates containing iminooxadiazinedione groups and their preparation can be found, for example, in EP-A798299, EP-A896009, EP-A962454 and EP-A962455.

The polyether polyols of components C) and D) can be obtained by techniques known per se in polyurethane chemistry, for example base-catalyzed alkoxylation by means of suitable starter molecules of ethylene oxide and/or propylene oxide. Conventional methods therefor are known to the person skilled in the art and are described, for example, in EP-A761708 or WO 97/40086.

Suitable starter molecules for the preparation of the polyether component C) are amino-containing molecules, such as 2-aminoethanol, 2- (methylamino) -ethanol, diethanolamine, triethanolamine, 3-amino-1-propanol, diisopropanolamine, 2-amino-2-hydroxymethyl-1, 3-propanediol, ethylenediamine, 1, 2-diaminopropane, 1, 3-diaminopropane, 1, 4-diaminobutane, 1, 6-diaminohexane, 1, 12-diaminododecane or mixtures thereof. Suitable starter molecules for the preparation of polyether component D) are generally polyols, such as ethylene glycol, 1, 2-and 1, 3-propanediol, 1, 2-, 1, 3-, 1, 4-and 2, 3-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, 1, 8-octanediol, 2-methyl-1, 3-propanediol, 2-dimethyl-1, 3-propanediol, 2-ethyl-2-butyl-1, 3-propanediol, 2, 4-trimethyl-1, 3-pentanediol, 2-ethyl-1, 3-hexanediol, higher molecular weight alpha, omega-alkanediols having from 9 to 18 carbon atoms, cyclohexanedimethanol, cyclohexanediol, glycerol, Trimethylolpropane, 1, 2, 4-butanetriol, 1, 2, 6-hexanetriol, bis (trimethylolpropane), pentaerythritol, sorbitol or mixtures thereof.

Preference is given to using the abovementioned types of starting materials in C) and D), where the functionality is preferably from 2 to 4.

It is also possible to use mixtures of starting materials containing amino groups and starting materials containing no amino groups to subsequently obtain mixtures of polyether components C) and D).

Particular preference is given to using polyethers based on triethanolamine and/or diaminoethane as component C), the amino-containing polyethers formed thereby having a molecular weight of from 500 to 6000, preferably from 1000 to 4500.

Particular preference is given to using polyethers based on ethylene glycol and/or 1, 2-propanediol as component D), the polyethers which are free of amino groups and are formed therefrom having a molecular weight of from 500 to 18,000, preferably from 1000 to 12,000, particularly preferably from 1500 to 8000.

The content of the amino group-containing polyethers is 5 to 60% by weight, preferably 10 to 50% by weight, based on the total amount of all polyethers used.

Ethylene oxide and/or propylene oxide are preferably used for the synthesis of the polyethers. The preparation of the polyethers used can be carried out either with base catalysis or by means of DMC catalysis, which is restricted to polyethers without amino groups.

The polyisocyanate mixtures according to the invention are preferably prepared by a two-stage process. For this purpose, the polyisocyanate A) is charged into a reaction vessel and reacted with the polyol component C) and optionally D). The polyisocyanate component B) is then added and mixed with the resulting reaction products of A) and C) and optionally D).

In a particular embodiment, the polyisocyanate mixtures according to the invention can also be prepared by the one-shot process. In this process, the polyisocyanate components A) and B) are charged in a reaction vessel, and then the polyol component C) and optionally D) are added and reacted with the polyisocyanate mixture of A) and B).

In a further preferred embodiment, a two-step process is used. For this purpose, the polyisocyanate component B) is charged into a reaction vessel and reacted with the polyol component C) and optionally D). The polyisocyanate component A) is then added and mixed with the resulting reaction products of B) and C) and optionally D).

The amount of compounds used for the reaction of A) with C) and optionally D) is preferably from 55 to 95% of A) and from 5 to 45% of C) and D), particularly preferably from 60 to 90% of A) and from 10 to 40% of C) and D), most particularly preferably from 65 to 85% of A) and from 15 to 35% of C) and D), based on the solvent-free component.

The amount of compounds used in B) and [ A) + C) + D) ] is preferably from 35 to 75% B) and from 25 to 65% of [ A) + C) + D) ], particularly preferably from 40 to 70% B) and from 30 to 60% of [ A) + C) + D) ], very particularly preferably from 45 to 65% B) and from 35 to 55% of [ A) + C) + D) ], based on the solvent-free component.

A) And the ratio of NCO groups in the compounds used in B) to the isocyanate-reactive functional groups of the polyether polyols used in C) and D) is preferably from 20: 1 to 55: 1, particularly preferably from 25: 1 to 50: 1, very particularly preferably from 30: 1 to 45: 1.

The preparation of the polyisocyanate mixtures according to the invention is generally carried out at temperatures of from 20 to 160 ℃, preferably from 30 to 140 ℃ and particularly preferably from 40 to 120 ℃ in order to react the polyether components C) and optionally D) with the polyisocyanate components A) and optionally B). Stabilizers, such as organic acids or acid chlorides, may also be concomitantly used.

To accelerate the urethanization, catalysts known per se, such as organometallic compounds (e.g. lead octoate, tin octoate, dibutyltin dilaurate) or amines (e.g. tertiary amines) can be used. If catalysts are concomitantly used, they are preferably used in amounts of from 0.001 to 5% by weight, in particular from 0.002 to 2% by weight, based on the total weight of the reactants.

The solids content of the polyisocyanate mixtures according to the invention at an outflow viscosity (DIN4mm beaker, 23 ℃) of 20s is > 50 to 75% by weight, particularly preferably > 50 to 70% by weight, which can be set by adding inert solvents of the type mentioned above. The polyisocyanate mixtures of the invention have an isocyanate content of from 7 to 15% by weight, preferably from 8 to 15% by weight, particularly preferably from 9 to 14% by weight.

The polyisocyanate mixtures according to the invention can be used for the production of quick-drying moisture-curing polyurethane coatings, for example for wood, which exhibit no tendency to crack formation even at low temperatures of-20 ℃. Furthermore, the polyisocyanate mixtures according to the invention are also suitable for the production of moisture-curing adhesives and sealants. However, their use as raw materials for paints and coatings is preferred.

The invention therefore further provides moisture-curing coatings, adhesives and sealants comprising

a) The polyisocyanate mixtures according to the invention are,

b) a catalyst to accelerate the reaction of free NCO groups with moisture; and

c) optionally auxiliary substances and additives.

As catalysts b) for accelerating the NCO/water reaction, it is possible to use, for example, tertiary amines, such as triethylamine, pyridine, picoline, benzyldimethylamine, N-ethylenepiperazine, N-methylpiperidine, pentamethyldiethylenetriamine, N-dimethylaminocyclohexane, N' -dimethylpiperazine, dimorpholinodiethylether or metal salts, such as iron (III) chloride, zinc 2-ethylhexanoate, tin (II) octanoate, tin (II) palmitate, dibutyltin (IV) dilaurate and molybdenum glycolate, or any mixtures of such catalysts. Most particularly preferred is the use of dimorpholinodiethyl ether.

Component b) is used in an amount of from 0.001 to 5% by weight, preferably from 0.01 to 3% by weight, particularly preferably from 0.05 to 2.5% by weight, most particularly preferably from 0.1 to 2.0% by weight, based on component a) (solids to solids).

The auxiliary substances and additives optionally present in component c) may be, for example, surface-active substances, grinding waxes, internal mould release agents, fillers, colorants, pigments, flame retardants, hydrolysis stabilizers, biocides, flow improvers, antioxidants, for example 2, 6-di-tert-butyl-4-methylphenol, UV absorbers of the 2-hydroxyphenylbenzotriazole type or light stabilizers of the HALS compound type which are substituted or unsubstituted on the nitrogen atom, for example292 and770DF(CibaGmbH, Lampertheim, DE) or other commercially available stabilizers and additives as described in "Lacgadertive" (JohanBieleman, Verlag Wiley-VHC Weinheim, New York, Chichester, Brisbane, Singapore, Toronto, 1998, pp 273-370), or any mixtures of these compounds.

The inert solvents already mentioned above can also be added here to adjust the viscosity.

It is also possible, but not preferred, to use other NCO-functional prepolymers in addition to the polyisocyanate mixtures a) according to the invention.

In the preparation of the coating compositions of the present invention, the individual components a) to c) are mixed together in any desired order.

The coating compositions according to the invention based on polyisocyanate mixtures can be applied to any desired substrate by methods known per se, for example by spraying, brushing, dipping (flood coat), pouring or by means of rollers or doctor blades. Examples of suitable substrates include metal, wood, glass, stone, ceramic materials, concrete, hard and soft plastics, textiles, leather, and paper. Wood is preferred.

Curing can be carried out at > 5 ℃, preferably at room temperature or elevated temperature.

All of the above references are hereby incorporated by reference in their entirety for all useful purposes.

While certain specific structures that embody the invention have been shown and described, it will be apparent to those skilled in the art that various modifications and rearrangements can be made without departing from the spirit and scope of the underlying concepts of the invention, which are not limited to the specific forms shown and described herein.

Examples

All percentages are by weight unless otherwise indicated.

The NCO content of the resins described in the examples and comparative examples was determined by titration in accordance with DIN 53185.

The dynamic viscosity was measured at 23 ℃ using a rotational viscometer (MCR 51, Anton Paar GmbH, D-73760 Ostfildern).

Hazen colour values were determined using a colour measuring instrument (LICO 400, Dr. Bruno Lange GmbH, D-40549 Dusseldorf).

The residual monomer content was determined by means of GC according to DIN 55956.

The lacquer cures at room temperature under the influence of atmospheric moisture. The relative humidity is 30 to 50%. 100% humidity is understood to be the maximum amount of moisture that the air can absorb at the respective temperature without forming water vapour.

IL 1451: TDI-based, isocyanurate group-containing polyisocyanates with a content of 51% by weight in butyl acetate, the isocyanate content was 7.4% by weight (commercial products from Bayer MaterialScience AG, Leverkusen, DE).

N3600: polyisocyanate based on 1, 6-hexamethylene diisocyanate having an isocyanate content of 23.0% by weight (commercial product of Bayer MaterialScience AG, Leverkusen, DE).

N3400: polyisocyanate based on 1, 6-hexamethylene diisocyanate having an isocyanate content of 21.8% by weight (commercial product of Bayer MaterialScience AG, Leverkusen, DE).

XP 2580: polyisocyanate based on 1, 6-hexamethylene diisocyanate with an isocyanate content of 20.0% by weight (test product of Bayer MaterialScience AG, Leverkusen, DE).

XP 2410: polyisocyanate based on 1, 6-hexamethylene diisocyanate with an isocyanate content of 23.5% by weight (test product of Bayer MaterialScience AG, Leverkusen, DE).

Polyisocyanate as a raw material

Polyisocyanate a 1:

18 g of a polyether from triethanolamine with a number-average molecular weight Mn of 1161 g/mol and a propylene oxide content of 86.9% by weightA mixture of a triol and 160 g of a polyether derived from propylene glycol having a number-average molecular weight Mn of 4007 g/mol, a propylene oxide content of 85.2% by weight and an ethylene oxide content of 13.1% by weight is added dropwise at 80 ℃ to 1003 gIL1451, 119 g butyl acetate and 0.65 g 2-chloropropionic acid. On completion of the addition, stirring was carried out at 80 ℃ until a theoretical NCO content of 5.3% by weight was reached. The resulting clear prepolymer solution had a solids content of 53.1% by weight, a viscosity at 23 ℃ of 682mPas, an NCO content of 5.2% by weight and a color value of 58 APHA.

Polyisocyanate a 2:

a mixture of 29 g of a triethanolamine-derived polyether triol having a number average molecular weight Mn of 1161 g/mol and a propylene oxide content of 86.9% by weight and 164 g of a propylene glycol-derived polyether having a number average molecular weight Mn of 4007 g/mol, a propylene oxide content of 85.2% by weight and an ethylene oxide content of 13.1% by weight was added dropwise to 1180 g of a propylene glycol-derived polyether at 80 deg.CIL1451, 127 g butyl acetate and 0.75 g 2-chloropropionic acid. On completion of the addition, stirring was carried out at 80 ℃ until a theoretical NCO content of 5.3% by weight was reached. The resulting clear prepolymer solution had a solids content of 52.8% by weight, a viscosity at 23 ℃ of 460mPas, an NCO content of 5.3% by weight and a color value of 61 APHA.

Polyisocyanate a 3:

a mixture of 38 g of a triethanolamine-derived polyether triol having a number average molecular weight Mn of 1161 g/mol and a propylene oxide content of 86.9% by weight and 151 g of a propylene glycol-derived polyether having a number average molecular weight Mn of 4007 g/mol, a propylene oxide content of 85.2% by weight and an ethylene oxide content of 13.1% by weight was added dropwise at 80 ℃ to 1190 g ofIL1451, 122 g butyl acetate and 0.75 g 2-chloropropionic acid. On completion of the addition, stirring was carried out at 80 ℃ until a theoretical NCO content of 5.3% by weight was reached. The resulting clear prepolymer solution had a solids content of 52.5% by weight, a viscosity at 23 ℃ of 580mPas, an NCO content of 5.3% by weight and a color value of 63 APHA.

Polyisocyanate a 4:

a mixture of 46 g of a triethanolamine-derived polyether triol having a number average molecular weight Mn of 1161 g/mol and a propylene oxide content of 86.9% by weight and 138 g of a propylene glycol-derived polyether having a number average molecular weight Mn of 4007 g/mol, a propylene oxide content of 85.2% by weight and an ethylene oxide content of 13.1% by weight was added dropwise at 80 ℃ to 1198 g of a propylene glycol-derived polyetherIL1451, 118 g butyl acetate and 0.75 g 2-chloropropionic acid. On completion of the addition, stirring was carried out at 80 ℃ until a theoretical NCO content of 5.3% by weight was reached. The clear prepolymer solution obtained had a solids content of 53.0% by weight, a viscosity at 23 ℃ of 719mPas, an NCO content of 5.2% by weight and a color value of 79 APHA.

Polyisocyanate a 5:

a mixture of 54 g of a triethanolamine-derived polyether triol having a number average molecular weight Mn of 1161 g/mol and a propylene oxide content of 86.9% by weight and 126 g of a propylene glycol-derived polyether having a number average molecular weight Mn of 4007 g/mol, a propylene oxide content of 85.2% by weight and an ethylene oxide content of 13.1% by weight was added dropwise at 80 ℃ to 1207 g ofIL1451, 114 g butyl acetate and 0.75 g 2-chloropropionic acid. On completion of the addition, stirring was carried out at 80 ℃ until a theoretical NCO content of 5.3% by weight was reached. The resulting clear prepolymer solution had a solids content of 52.9% by weight, a viscosity at 23 ℃ of 769mPas, an NCO content of 5.3% by weight and a color value of 75 APHA.

Polyisocyanate B1:

mixing the powder with water in a volume of 2000 gN3400 was added dropwise to 2000 gN3600, and stirring at 60 ℃ for 30 minutes. A clear polyisocyanate mixture having a viscosity of 447mPas, an isocyanate content of 22.2% by weight and a color value of 11APHA was obtained.

Polyisocyanate B2:

2667 g ofN3400 was added dropwise to 1333 gN3600, and stirring at 60 ℃ for 30 minutes. A clear polyisocyanate mixture having a viscosity of 285mPas, an isocyanate content of 21.9% by weight and a color value of 10APHA was obtained.

Polyisocyanate B3:

1733 gN3400 was added dropwise to 3467 gN3600, and stirring at 60 ℃ for 30 minutes. A clear polyisocyanate mixture having a viscosity of 567mPas, an isocyanate content of 22.5% by weight and a color value of 16APHA was obtained.

Polyisocyanate 1 (according to the invention):

62% by weight of polyisocyanate A5 and 38% by weightA mixture of N3400. A clear polyisocyanate mixture having a solids content of 71.5% by weight, a viscosity of 845mPas, an NCO content of 11.6% by weight and a color number of 53APHA was obtained.

Polyisocyanate 2 (according to the invention):

56% by weight of polyisocyanate A5 and 44% by weightA mixture of N3600. A clear polyisocyanate mixture having a solids content of 73.1% by weight, a viscosity of 1120mPas, an NCO content of 13.1% by weight and a color number of 49APHA was obtained.

Polyisocyanate 3 (according to the invention) (hand-mix):

60% by weight of polyisocyanate A1 and 40% by weightMixtures of XP 2580. A clear polyisocyanate mixture having a solids content of 71.2% by weight, a viscosity of 500mPas, an NCO content of 10.8% by weight and a color number of 77APHA was obtained.

Polyisocyanate 4 (according to the invention) (hand-mix):

58% by weight of polyisocyanate A2 and 42% by weightMixtures of XP 2410. A clear polyisocyanate mixture having a solids content of 72.3% by weight, a viscosity of 665mPas, an NCO content of 12.7% by weight and a color value of 58APHA was obtained.

Polyisocyanate 5 (according to the invention) (hand-mix):

a mixture of 61% by weight of polyisocyanate A3 and 39% by weight of polyisocyanate B2. A clear polyisocyanate mixture having a solids content of 70.6% by weight, a viscosity of 597mPas, an NCO content of 11.6% by weight and a color of 53APHA was obtained.

Polyisocyanate 6 (according to the invention) (hand-mix):

a mixture of 57% by weight of polyisocyanate A5 and 43% by weight of polyisocyanate B3. A clear polyisocyanate mixture having a solids content of 72.5% by weight, a viscosity of 969mPas, an NCO content of 12.4% by weight and a color of 71APHA was obtained.

Polyisocyanate 7 (according to the invention) (hand-mix):

a mixture of 60% by weight of polyisocyanate A4 and 40% by weight of polyisocyanate B1. A clear polyisocyanate mixture having a solids content of 71.9% by weight, a viscosity of 614mPas, an NCO content of 12.1% by weight and a color number of 136APHA was obtained.

Polyisocyanate 8 (according to the invention):

a mixture of 22 g of triethanolamine-derived polyether triol having a number-average molecular weight Mn of 1161 g/mol and a propylene oxide content of 86.9% by weight and 52 g of propylene glycol-derived polyether having a number-average molecular weight Mn of 4007 g/mol, a propylene oxide content of 85.2% by weight and an ethylene oxide content of 13.1% by weight was added dropwise to 499 g of polyether polyol at 80 deg.CIL1451, 380 gN3400, 47 g butyl acetate and 0.31 g 2-chloropropionic acid. On completion of the addition, stirring was carried out at 80 ℃ until a theoretical NCO content of 11.6% by weight was reached. The resulting clear polyisocyanate mixture had a solids content of 71.1% by weight, a viscosity at 23 ℃ of 690mPas, an NCO content of 11.1% by weight and a color value of 129 APHA.

Polyisocyanate 9 (comparative)

The working up of the polyisocyanate 1 of EP-A1582543 and adjusting the mixture to 50% by weight solids content with butyl acetate. A polyisocyanate mixture having a solids content of 50.3% by weight, a viscosity of 238mPas, an NCO content of 4.1% by weight and a color number of 88APHA was obtained.

Paint test

Polyisocyanates were formulated as a cover coat (coveringlacquer) according to the following basic formulation:

the polyisocyanate was adjusted to an outflow viscosity of about 20s with butyl acetate (DIN4mm beaker, at 23 ℃, DIN 53211). 0.75% by weight (based on the presentation form) of dimorpholinodiethylether is additionally added to the polyisocyanates according to the invention, which also contain aliphatic polyisocyanates as well as aromatic polyisocyanates.

The following tests were carried out:

1. stability was determined by observing the evolution of viscosity after 1 day of storage at room temperature and after 15 days of storage in a closed container at 50 ℃. The efflux time was determined in accordance with DIN 53211. Stability is said to be in progress when the ratio of the flow-off time after storage to the flow-off time before storage is < 2.

2. Determination of the coating paint according to DIN 53157And (6) measuring the hardness.

3. To determine the drying rate, the sand-free drying of a 240 μm thick wet paint film on a glass plate was determined in minutes¹⁾Contact drying²⁾And completely drying³⁾。

Sand removing and drying:

to determine surface drying, sand grains were carefully applied to the paint layer to be tested. After leaving for 1 minute, they were brushed off with a vicuna camel hair brush without pressure and the paint layer was visually inspected for any remaining grit.

And (3) contact drying:

the final lacquer was applied to a glass plate in the desired wet film layer thickness (240 μm) and dried at room temperature. At designated time intervals determined by the expected expiration time, the surface was tested with the thumb to see if it was still tacky. When the surface is no longer tacky, the sample is contact-dried.

And (3) completely drying:

the final lacquer was applied to a glass plate in the desired wet film layer thickness (240 μm) and dried at room temperature. A pressure of 2-3kp (if necessary, pre-check scale) is applied to the film with the thumb at specified time intervals determined by the expected end time. The end point of this measurement is the time when the stamp is no longer visible under oblique light.

4. To determine the solvent resistance, the paint films were exposed for 1 minute after 24 hours and after 7 days in absorbent cotton (cotton-wood) sticks soaked with the following solvents: acetone, and a 1: 1 mixture of butyl acetate and ethyl acetate. The samples were then visually inspected after being scored with a finger. Grade 0 means very poor (film dissolution) and grade 5 means very good (no visible change).

5. Scratch resistance was determined as follows: after the indicated time, the paint film which had cured at room temperature was scratched with a fingernail. To do this, the wrist is placed on the test board so that the fingernail falls vertically on the painted surface. While applying light pressure, the nail was moved back and forth across the surface with bumps (typically 10 times back and forth) and visually scratched. Grade 0 means very poor (complete destruction of the coating) and grade 5 means very good (no visible change).

6. Gardner gloss was measured after 24 hours and after 7 days.

7. The yellowing tendency was determined as follows: 180 micron paint was applied to white porcelain (200X 100 mm). The cured sample was stored behind the glass (45 ° angle and south). Color values (CIELAB, Byk Gardner Color Guide 45/0) were measured before storage and after the indicated times. A paint-free porcelain was used as a standard/reference. Δ E between the sample and the reference was measured.

And (3) test results:

visual inspection of the first value/visual inspection of the second value after scratching with fingernails

Discussion of test results:

after adjustment to a processing viscosity of 20s (DIN4mm beaker 23 ℃), the covering lacquers according to the invention based on polyisocyanates 1 and 2 have a solids content of 54.4% by weight, whereas the solids content of the comparative polyisocyanate 9 (40.0% by weight) is much lower at the same viscosity. All paints dry at a fairly rapid rate, but the paints according to the invention exhibit a faster development of hardness and a higher final hardness. The scratch resistance of the inventive paint was superior to the comparative paint. The solvent resistance of the inventive paints, especially after only 24 hours, is clearly superior to that of the comparative paints. The gloss of all paints is similarly at a high level, but the paints of the invention have a significantly lower tendency to yellowing than the comparative paints.

Claims (9)

1. Solvent-containing polyisocyanate mixture having a solvent content of less than 50% by weight, an NCO content of 7 to 15% by weight, a monomeric TDI content of less than 0.2% by weight and a monomeric aliphatic and/or cycloaliphatic isocyanate content of less than 0.2% by weight at an outflow viscosity of 20s at 23 ℃ using a DIN4mm beaker according to DIN 53211, wherein the mixture consists of the reaction products of a) and B) and at least one of components a) and/or B) with C) and optionally D):

A) a TDI component comprising a TDI isocyanurate polyisocyanate;

B) an aliphatic and/or alicyclic isocyanate component containing an aliphatic and/or alicyclic polyisocyanate;

C) at least one polyether polyol containing at least one tertiary nitrogen atom having a number average molecular weight of from 500 to 4000 g/mole; and

D) optionally at least one polyether polyol free of nitrogen atoms.

2. A process for preparing a solvent-containing polyisocyanate mixture according to claim 1 wherein

A) A TDI component comprising a TDI isocyanurate polyisocyanate; and

B) aliphatic and/or alicyclic isocyanate component containing aliphatic and/or alicyclic polyisocyanate

By reacting at least one of the two components A) and/or B) with

C) At least one polyether polyol containing at least one tertiary nitrogen atom having a number average molecular weight of from 500 to 4000 g/mole; and

D) optionally at least one polyether polyol free of nitrogen atoms.

3. The process of claim 2, wherein the process is carried out with concomitant use of a stabilizer and a catalyst.

4. The process of claim 2, wherein A) is used in an amount of from 55 to 95% by weight and B) is used in an amount of from 5 to 45% by weight, based on the total amount of A) and B).

5. A coating comprising

a) A solvent-containing polyisocyanate mixture of claim 1;

b) a catalyst to accelerate the reaction of free NCO groups with moisture; and

c) one or more auxiliary substances and additives.

6. Coating, adhesive and/or sealant comprising the solvent-containing polyisocyanate mixture of claim 1.

7. An adhesive comprising the solvent-containing polyisocyanate mixture of claim 1.

8. A sealant comprising the solvent-containing polyisocyanate mixture of claim 1.

9. A substrate coated with a coating comprising the solvent-containing polyisocyanate mixture of claim 1.