DE102008050916A1 - Two-component polyurethane lacquer containing silanized polyisocyanate hardeners, process for the preparation of silanized polyisocyanate hardeners and hardeners prepared by the process - Google Patents

Abstract

The present invention relates to a process for the preparation of partially or completely silanized polyisocyanate hardeners by reacting a polyisocyanate with an amino-functional silane. In the process, hexamethylene diisocyanate and / or a polyisocyanate derived by trimerization, dimerization, urethane, biuret or allophanate formation of hexamethylene diisocyanate in butyl acetate as solvent or in a solvent mixture containing at least 60 wt .-% butyl acetate, based on the total weight of the solvent mixture, contains reacted in the presence of a water scavenger with at least one amino-functional silane. The invention also relates to polyisocyanate hardener prepared by the process.

Description

The The present invention relates to two-component polyurethane paints containing polyols and partially or completely silanized Polyisocyanate hardener, a process for the preparation of partially or completely silanized polyisocyanate hardeners by reacting a polyisocyanate with an amino-functional Silane and prepared by the process polyisocyanate hardener.

Two-component polyurethane paints (PUR coatings) are used because of their good resistance to environmental influences, especially acid rain, for topcoating in the automotive industry used. As a rule, OH-functional poly (meth) acrylate resins are found here and polyisocyanates based on hexamethylene diisocyanate (HDI) Use. The good resistance to environmental influences may be due to the partial use of isophorone diisocyanate polyisocyanates (IPDI) are again significantly improved. A disadvantage of the described However, paints is insufficient scratch resistance the topcoat.

The Scratch resistance can be due to the use of silanized Polyisocyanate hardeners are improved, d. H. through crosslinkers, containing the isocyanate groups and silane groups. However, this succeeds only if suitable catalysts for crosslinking the silanes be added.

From the European patent applications EP 1 193 278 A1 and EP 1 273 640 A2 non-aqueous, thermosetting two-component coating compositions are known which contain as binder a solvent-containing polyol component and as a curing agent consisting of at least one aliphatic and / or cycloaliphatic polyisocyanate having an NCO functionality of 2 to 6 crosslinking component. In this case, from 0.1 to 95 mol% of the originally present free isocyanate groups of the polyisocyanate are reacted with N-alkyl and / or N-aryl-3-aminopropyltrialkoxysilanes or M, N-bis (3-trialkoxysilylpropyl) amines. The crosslinker component is prepared by reacting a polyisocyanate in a solvent with said amine functional silane compounds. In the case of IPDI polyisocyanate, a solvent mixture consisting of butyl acetate and Solvesso 100 in the ratio 1: 2 is used. The reaction of HDI polyisocyanate is carried out in pure Solvesso 100. Solvesso 100 is a trade name for an aromatic hydrocarbon mixture containing 1,2,4-trimethylbenzene, methylene, xylene, propylbenzene and isopropylbenzene.

The known silanized polyisocyanate hardeners have the Disadvantage of that they already at slightly elevated in storage Temperature, for example, at 40 ° C, for gelation and prone to yellowing.

It Object of the present invention, the disadvantages mentioned to avoid the prior art and a two-component polyurethane paint of the type mentioned above, the silanized polyisocyanate hardener contains, even with prolonged storage no Show gelation and no yellowing. It is still the task the present invention, a corresponding method for producing the silanized polyisocyanate hardener and corresponding hardeners specify.

Surprisingly was found to solve this problem can that the two-component polyurethane paint polyisocyanate hardener contains in a solvent mixture with a high Proportion of butyl acetate or in pure butyl acetate in the presence at least a water catcher are produced.

object The present invention is therefore a two-component polyurethane paint of the type mentioned above, which is characterized in that the partially or completely silanized polyisocyanate hardeners can be prepared by reacting a polyisocyanate with a amino-functional silane, where as polyisocyanate hexamethylene diisocyanate and / or a by trimerization, dimerization, urethane, biuret or allophanate formation derived from hexamethylene diisocyanate Polyisocyanate in butyl acetate as a solvent or in a Solvent mixture containing at least 60% by weight of butyl acetate, based on the total weight of the solvent mixture, contains in the presence of at least one water catcher is reacted with at least one amino-functional silane.

advantageous Embodiments of the invention will become apparent from the dependent claims.

In a preferred embodiment of the invention the paint according to the invention at least one water scavenger. The person skilled in the art understands a compound under a water scavenger, which has the property of trapping traces of moisture. The Effect is usually such that the water catcher Water or moisture binds with elimination of an alcohol.

When Water scavengers will advantageously be trialkyl orthoformate used. Triethyl orthoformate is particularly preferred as the water scavenger used.

Of the Paint including hardener preferably contains at least 0.5% by weight, preferably at least 2.0% by weight, especially preferably at least 3.0% by weight and in particular at least 4.0 Wt .-% of a water scavenger, based on the total solids content of the paint.

The Polyol of the paint according to the invention is preferably selected from the group consisting of hydroxyl-containing (Meth) acrylic copolymers, saturated polyester polyols, Polycarbonate diols, polyether polyols and urethane and ester groups Polyols alone or in mixtures. Hydroxyl-containing (meth) acrylic copolymers are particularly preferred.

As hydroxyl-containing (meth) acrylic copolymers, resins having a monomer composition, as z. In WO 93/15849 (P. 8, line 25 to p. 10, line 5), or also in DE 195 29 124 described are used. The acid number of the (meth) acrylic copolymer to be set as the monomer by proportionate use of (meth) acrylic acid should be 0-30, preferably 3-15. The number average molecular weight (determined by gel permeation chromatography against a polystyrene standard) of the (meth) acrylic copolymer is preferably 2,000-20,000 g / mol, the glass transition temperature is preferably -40 ° C to + 60 ° C. The glass transition temperature is determined by calorimetric measurement (DSC, Differential Scanning Calorimetry) ISO 11357-2 measured. The hydroxyl content of the (meth) acrylic copolymers to be used in accordance with the invention by proportionate use of hydroxylalkyl (meth) acrylates is preferably 70-250 mg KOH / g, more preferably 90-190 mg KOH / g. The OH number is determined by calculation.

Suitable polyester polyols are resins having a monomer composition of di- and polycarboxylic acids and di- and polyols, as described, for. In Stoye / Freitag, Lackharze, C. Hanser Verlag, 1996, p. 49 or in WO 93/15849 are described. As polyester polyols and polyaddition products of caprolactone and low molecular weight diols and triols, such as. B. under the name TONE (Union Carbide Corp.) or CAPA (Solvay / Interox) available, can be used. The calculated number average molecular weight is preferably 500-5,000 g / mol, more preferably 800-3,000 g / mol, the average functionality is 2.0-4.0, preferably 2.0-3.5.

As urethane- and ester-group-containing polyols are in principle those used as in EP 140 186 are described. Preference is given to urethane- and ester-group-containing polyols, for the preparation of which HDI, IPDI, trimethylhexamethylene diisocyanate (TMDI) or (H ₁₂ -MDI) are used. The number average molecular weight is preferably 500-2000 g / mol, the average functionality 2.0-3.5.

It is preferred that the paint solvent or solvent mixtures containing aromatic hydrocarbons such as 1,2,4-trimethylbenzene, Mesitylene, xylene, propylbenzene and isopropylbenzene exist. One preferred solvent mixture is solvent naphtha.

object The present invention is further a method of the preamble mentioned type by reaction of a polyisocyanate with an amino-functional Silane, which is characterized in that as polyisocyanate hexamethylene diisocyanate and / or a by trimerization, dimerization, urethane, biuret or allophanate formation derived from hexamethylene diisocyanate Polyisocyanate in butyl acetate as a solvent or in a Solvent mixture containing at least 60% by weight of butyl acetate, based on the total weight of the solvent mixture, contains in the presence of at least one water catcher is reacted with at least one amino-functional silane

object the invention are also partially producible by the method or completely silanized polyisocyanate hardener.

Around the scratch resistance of using the invention Polyisocyanate hardener producible two-component paints To improve, it is advantageous that more than 10%, in particular more than 20%, preferably more than 30%, and more preferably more as 40% of the free isocyanate groups of Isocyanateduktes with amino functional Silanes be implemented. A particularly good scratch resistance is achieved when more than 70% of the free isocyanate groups of Isocyaniertuktes be reacted with amino-functional silanes. Be as silanes advantageously alkoxysilanes, particularly preferably methoxysilanes, used.

One The most preferred silane is bis-N-alkyl-3-aminopropyltrimethoxysilane.

Of the Solid content of the invention Polyisocyanate is advantageously at least 50% by weight, preferably at least 70% by weight.

When Water scavengers will advantageously be trialkyl orthoformate used.

When Water scavenger is most preferably triethyl orthoformate used.

Preferably during synthesis are at least 1 wt .-%, preferably at least 2% by weight and more preferably at least 3% by weight a water catcher based on the total solids content added to the reaction mixture.

Prefers during synthesis are at least 1 wt .-%, preferably at least 2% by weight and more preferably at least 3% by weight Triethyl orthoformate based on the total solids content added to the reaction mixture.

It it is preferred that the solvent mixture in which the Polyisocyanate hardener are prepared, at least 80 wt .-% Contains butyl acetate. Particularly preferably contains the solvent mixture at least 95 wt .-% butyl acetate. Very particularly advantageous is worked in pure butyl acetate.

A alternative embodiment of the invention Method is characterized in that in a first step a maximum of one of the isocyanate groups per molecule of the hexamethylene diisocyanate reacted with the amino-functional silane and in a second step, the intermediate obtained by dimerization, trimerization, urethane, biuret or allophanate formation is reacted to a polyisocyanate.

The exact structure of the polyisocyanate hardener according to the invention is not known, but they point in particular to the Reduction or prevention of gel formation and yellowing significantly improved properties over those in the state hardeners known to the art. In this respect it can be assumed that by the inventive method new Hardeners are manufactured, which in the state of the art so far were not known.

The Hardener according to the invention can in combination with a polyol component in pigmented and not pigmented two-component paints are used. in principle are all polyols with more than two OH groups as the polyol component suitable. Particularly suitable are hydroxyl-containing (meth) acrylic copolymers, saturated polyester polyols, polycarbonate diols, polyether polyols or urethane and ester group-containing polyols alone or in mixtures.

suitable Polyols are known from the already mentioned prior art.

in the The following is the invention with reference to embodiments explained in more detail.

Production Example 1 - Production a butyl acetate hardener according to the invention

In A round bottomed flask with reflux condenser was added 36.296 parts by weight of Basonat HI 100 (available from the BASF AG, Ludwigshafen), 36.093 parts by weight of butyl acetate, 56.98 Parts by weight of solvent naphtha and 2.458 parts by weight of triethylorthoformate submitted. 1,786 parts by weight Dynasilan 1189 (commercially available from the company Evonik) and 23.367 parts by weight of Dynasilan 1124 (also commercially available from Evonik) were premixed and slowly at room temperature under reflux and nitrogen blanketing dosed in such a way that the product temperature does not exceed 60 ° C. Subsequently, the reaction mixture was at 60 ° C tempered and maintained until the residual NCO content reaches 4.9% had (NCO determination by titration).

Comparative Example 2 - Preparation a solvent naphtha hardener

36.969 parts by weight of Basonat HI 100 (available from BASF AG, Ludwigshafen), 36.093 parts by weight of solvent naphtha and 2.458 parts by weight of triethyl orthoformate were initially charged in a round-bottomed flask with reflux condenser. 1786 parts by weight of Dynasilan 1189 (commercially available from Evonik) and 23.367 parts by weight of Dynasilan 1124 (also commercially available from Evonik) were premixed and added slowly at room temperature under reflux and nitrogen blanketing so that the product temperature does not exceed 60 ° C. Subsequently, the reaction mixture was heated to 60 ° C and held until the residual NCO content had reached 4.9% (NCO determination by titration).

Comparative Example 3 - Preparation an ethylethoxypropionate hardener

In A round bottomed flask with reflux condenser was added 36.296 parts by weight of Basonat HI 100 (available from the BASF AG, Ludwigshafen), 36.093 parts by weight of ethyl ethoxypropionate and 2.458 parts by weight of triethyl orthoformate. 1,786 parts by weight Dynasilan 1189 (commercially available from Evonik) and 23.367 parts by weight of Dynasilan 1124 (also commercially available from Evonik) were premixed and slowly at room temperature under reflux and nitrogen blanketing dosed in such a way that the product temperature does not exceed 60 ° C. Subsequently, the reaction mixture was at 60 ° C tempered and maintained until the residual NCO content reaches 4.9% had (NCO determination by titration).

Comparative Example 4 - Preparation a pentyl acetate hardener

In A round bottomed flask with reflux condenser was added 36.296 parts by weight of Basonat HI 100 (available from the BASF AG, Ludwigshafen), 36.093 parts by weight of pentyl acetate and 2.458 Parts by weight of triethyl orthoformate submitted. 1,786 parts by weight Dynasilan 1189 (commercially available from Evonik) and 23.367 parts by weight of Dynasilan 1124 (also commercially available from Evonik) were premixed and slowly at room temperature under reflux and nitrogen blanketing dosed in such a way that the product temperature does not exceed 60 ° C. Subsequently, the reaction mixture was at 60 ° C tempered and maintained until the residual NCO content reaches 4.9% had (NCO determination by titration).

Comparative Example 5 - Preparation an ethoxy propyl acetate hardener

In A round bottomed flask with reflux condenser was added 36.296 parts by weight of Basonat HI 100 (available from the BASF AG, Ludwigshafen), 36.093 parts by weight of ethoxypropyl acetate and 2.458 parts by weight of triethyl orthoformate. 1,786 parts by weight Dynasilan 1189 (commercially available from Evonik) and 23.367 parts by weight of Dynasilan 1124 (also commercially available from Evonik) were premixed and slowly at room temperature under reflux and nitrogen blanketing dosed in such a way that the product temperature does not exceed 60 ° C. Subsequently, the reaction mixture was at 60 ° C tempered and maintained until the residual NCO content reaches 4.9% had (NCO determination by titration).

Properties of the invention Hardener - examples

Example 1 - Results of Storage Stabilities 40 ° C Shelf life (measured in DIN4 cup) Beginning after 7 days of exercise after 21 days of exercise After 28 days of stress Production Example 1 18 sec. 18 sec. - 18 sec. - 18 sec. - Comparative Example 2 20 sec. 21 sec. + 5% 24 sec. + 20% 24 sec. + 20% Comparative Example 3 23 sec. 25 sec. + 9% 27 sec. + 17% 27 sec. + 17% Comparative Example 4 20 sec. 21 sec. + 5% 23 sec. + 15% 23 sec. + 15% Comparative Example 5 24 sec. 25 sec. + 4% 27 sec. + 13% 27 sec. + 13% Example 2 - Results Color Number Hazen color number (measured n. 50 days RT) Production Example 1 3 Comparative Example 2 56 Comparative Example 3 23 Comparative Example 4 36 Comparative Example 5 29

Formulation of the invention Clearcoats - examples

Example 1 - Compatibility Enhancer 2K clearcoat with good scratch resistance

Based on the isocyanates described in the examples, the following formulations were formulated: component parts by weight Acrylate-based polyol 34,55 Polyol-based rheology auxiliaries 20.00 butyl 14.00 water scavenger 3.00 Non-silicone leveling agent 0.20 light stabilizer 2.82 blocked phosphoric acid catalyst 5.30 base 0.03 butanol 0.07 Production Example 1 80.60

Of the Clearcoat was on predried aqueous black Basecoat (predrying conditions: 10 minutes 80 ° C) applied and at 140 ° C over a period of 22 minutes hardened. This resulted in high-gloss surfaces, with regard to their micro penetration hardness, scratch resistance and chemical resistance were examined.

The results were as follows: Micro penetration hardness (30 Nm ² ): 125.64 n / mm ² Hammer test (RG after 100 DH): % 80,9 Beginning of damage n. 24 h RT Sulfuric acid 1% Hydrochloric acid 10% Nitric acid 1% Caustic soda 5% pancreatin tree resin water 51 54 42 54 <37 60 > 80

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - EP 1193278 A1 [0004]
• - EP 1273640 A2 [0004]
• WO 93/15849 [0014, 0015]
• - DE 19529124 [0014]
• - EP 140186 [0016]

Cited non-patent literature

• - ISO 11357-2 [0014]
• Stoye / Freitag, Lackharze, C. Hanser Verlag, 1996, p. 49 [0015]

Claims (21)

Two-component polyurethane paint comprising at least one polyol and at least one partially or completely silanized polyisocyanate hardener, characterized in that the partially or completely silanized polyisocyanate hardener can be prepared by reacting a polyisocyanate with an amino-functional silane, wherein polyisocyanate hexamethylene diisocyanate and / or by trimerization, Dimerization, urethane, biuret or allophanate formation of hexamethylene diisocyanate-derived polyisocyanate in butyl acetate as a solvent or in a solvent mixture containing at least 60 wt .-% butyl acetate, based on the total weight of the solvent mixture, reacted in the presence of at least one water scavenger with at least one amino-functional silane becomes. Two-component polyurethane paint after one of the previous Claims, characterized in that the paint at least contains a water catcher. Two-component polyurethane paint after one of the previous Claims, characterized in that the polyol is selected is from the group consisting of hydroxyl-containing (meth) acrylic copolymers, saturated polyester polyols, polycarbonate diols, polyether polyols and urethane and ester group-containing polyols alone or in mixtures. Two-component polyurethane paint after one of the previous Claims, characterized in that the polyol a hydroyl group-containing (meth) acrylic copolymer is. Process for the preparation of partial or complete silanized polyisocyanate hardeners by reaction of a Polyisocyanate with an amino-functional silane, characterized that as polyisocyanate hexamethylene diisocyanate and / or a by Trimerization, dimerization, urethane, biuret or allophanate formation hexamethylene diisocyanate-derived polyisocyanate in butyl acetate as a solvent or in a solvent mixture, the at least 60% by weight of butyl acetate, based on the total weight of the solvent mixture, contains in the presence at least one water scavenger having at least one amino functional Silane is implemented. Method according to claim 5, characterized in that that more than 10% of the free isocyanate groups of Isocyaniertuktes be reacted with amino-functional silanes. Method according to claim 5, characterized in that that more than 20%, preferably more than 30%, more preferably more as 40% of the free isocyanate groups of the isocyanate with amino-functional silanes be implemented. Method according to claim 5, characterized in that that more than 70% of the free isocyanate groups of Isocyaniertuktes be reacted with amino-functional silanes. Method according to Claims 5 to 8, characterized that are used as silanes alkoxysilanes. Method according to claim 9, characterized in that that are used as silanes methoxysilanes. Method according to claim 10, characterized in that that used as silane bis-N-alkyl-3-aminopropyltrimethoxysilane becomes. Method according to claims 5 to 11, characterized in that that the solids content of the resulting hardener at least 50 wt .-% is. Method according to claims 5 to 11, characterized in that that the solids content of the resulting hardener at least 70 wt .-% is. Method according to claims 5 to 13, characterized as a water scavenger, a trialkyl orthoformate is used. Method according to claims 5 to 14, characterized that triethyl orthoformate is used as the water scavenger. Method according to claims 5 to 15, characterized that during the synthesis at least 1 wt .-% based on the total solids content of the reaction mixture of a Water catcher are added. Method according to claims 5 to 15, characterized that during the synthesis at least 2 wt .-% based on the total solids content of the reaction mixture of a Water catcher are added. Method according to claims 5 to 15, characterized that during the synthesis at least 3 wt .-% based on the total solids content of the reaction mixture of a Water catcher are added. Method according to claims 5 to 18, characterized the solvent mixture contains at least 80% by weight of butyl acetate contains. Method according to claims 5 to 19, characterized that in a first step on average per molecule maximum one of the isocyanate groups of hexamethylene diisocyanate with the amino functional Silane is reacted and in a second step, the obtained Intermediate by dimerization, trimerization, urethane, biuret or allophanate formation is converted to a polyisocyanate. Partial or fully silanized Polyisocyanate hardener obtainable by a process according to one of claims 5 to 20.