EP3080181A1

EP3080181A1 - Coating composition in the form of a non-aqueous transparent dispersion

Info

Publication number: EP3080181A1
Application number: EP14809893.2A
Authority: EP
Inventors: Kirsten Siebertz; Klaus-Uwe Koch; Jorge Prieto
Original assignee: Dritte Patentportfolio Beteiligungs GmbH and Co KG
Current assignee: LEHMANN & VOSS & CO. KG
Priority date: 2013-12-12
Filing date: 2014-12-12
Publication date: 2016-10-19
Also published as: KR20160106601A; CA2932234A1; WO2015086796A1; JP2017508015A; MX2016007256A; CN105960423A; US20160297991A1

Abstract

The invention relates to a coating composition in the form of a non-aqueous transparent dispersion, comprising a reactive diluent, polyurethane (meth)acrylate particles, which can be obtained by reacting a polyisocyanate with a polyol and a nucleophilically functionalized (meth)acrylic acid ester in the reactive diluent in order to form polyurethane (meth)acrylate particles having a mean diameter of less than 40 nm, and an initiator. Corresponding coating compositions are distinguished by especially favorable properties in particular with regard to the adhesive strength, hardness, and microscratch resistance of said coating compositions after the curing of said coating compositions and therefore are superior to conventionally available coating product without nanoparticulate polyurethane (meth)acrylate particles in many cases.

Description

Lacquer composition in the form of a non-aqueous transparent dispersion

description

The invention relates to coating compositions in the form of nonaqueous transparent dispersions which are obtainable as reactive diluents, polyurethane (meth) acrylate particles which are obtainable by reacting a polyisocyanate with a polyol and a nucleophilically functionalized (meth) acrylic ester in the reactive diluent and have an average diameter of less than 40 nm, and contain an initiator.

Non-aqueous polyurethane dispersions have gained importance in recent years. They are used, inter alia, as a coating, adhesive and adhesive.

The documents DE 32 48 132, DE 35 13 248, EP 0 320 690 and EP 0 318 939 do not describe aqueous dispersions of polyurethanes for predominant use as coating compositions. The solvent consists of a

Hydrocarbon. The curing takes place by evaporation of the solvent, resulting in a thin layer of the previously dispersed

Polyurethane particles forms. The dispersion from DE 32 48 132 is known as

opaque).

DE 10 2005 035 235 A1 describes nonaqueous transparent dispersions of polyurethane (meth) acrylate particles in a reactive diluent obtainable by reacting a polyisocyanate with at least one polyol and a nucleophilically functionalized (meth) acrylic ester in the reactive diluent and characterized in that the polyurethane (meth) acrylate particles have an average diameter of less than 40 nm. DE 10 2005 035 235 A1 describes corresponding compositions for use as adhesive systems and castables and states that the solid-state cured dispersions have excellent impact strength properties and high tensile shear strength.

However, the compositions described in this application, especially for paint applications have insufficient properties, such as, among other things, an unfavorable viscosity. Accordingly, there is a need for compositions for paint applications that are completely transparent after cure and, at the same time, have an improved property profile in terms of their application properties, especially their adhesive strength, hardness and resistance to micro-scratches. These properties are particularly in the use of the compositions as a varnish of

Significance, because on the one hand lacquers should be as transparent as possible, on the other hand, however, the substrate or product underneath should be well shielded from external influences and protected, so that it is not damaged by everyday use.

In view of the prior art, it was an object of the present invention

Invention to provide Lackzusammensetzu lengths based on polyurethane dispersions, which have improved properties over the prior art and in addition to a high transparency after curing have a favorable adhesion, hardness and resistance to micro scratches. Another object was to provide a dispersion that is available from as few components as possible in order to produce the corresponding

Simplify dispersions. In addition, the production of the

Dispersion according to the invention as possible with components that are available easily and inexpensively.

Object of the present invention, it was also also adhesive and

To provide coating formulations based on polyurethane dispersions, which have improved properties over the prior art and in addition to a high transparency after curing have a high impact resistance and tensile shear strength. So should in particular on the addition of external Stabilizers can be dispensed without the stability of the dispersion is impaired.

The above-described objects, as well as others which, although not literal, but which can be deduced from and necessarily result from the contexts discussed herein, are achieved with a coating composition in the form of a nonaqueous transparent dispersion comprising: a reactive diluent

Polyurethane (meth) acrylate particles obtainable by reacting at least one polyisocyanate with at least one polyol and at least one nucleophilically functionalized (meth) acrylic ester in the

Reactive thinner to polyurethane (meth) acrylate particles with a middle

Diameter of less than 40 nm, and

- an initiator. Accordingly, the present invention provides a

Paint composition in the form of a non-aqueous transparent dispersion, which functionalized on the one hand with methacrylic acid esters

Polyurethane (meth) acrylate particles and on the other hand contains a reactive diluent and an initiator with which it is possible to functionalized

Polyurethane (meth) acrylate particles in the polymerization of the reactive diluent to covalently integrate into the matrix of the reactive diluent. An advantage of such coating compositions is that they are transparent and remain transparent even after curing of the reactive diluent. The coating composition according to the invention can be used directly as a lacquer, but it is also possible to add further additives and additives customary in lacquers to the composition, or to mix the composition with commercially available lacquer compositions and to use the formulation obtained therefrom as lacquer.

The paint of the invention has in the form of the cured dispersion, mediated by the contained polyurethane (meth) acrylate particles, a excellent adhesion to various substrates, excellent hardness and microcracking resistance.

A further advantage of the described dispersions is that they can be used over a longer period, i. h., At least two months, are stable at room temperature and therefore storable.

The term "nucleophilic functionalized (meth) acrylic acid ester" in the context of this invention denotes a (meth) acrylic acid ester which carries in its alcohol-derived radical a nucleophilic functional group which reacts with free isocyanate groups. Preferred nucleophilic groups are hydroxy, amino and mercapto groups. Particularly preferred is a hydroxy group. The most preferred nucleophilic functionalized (meth) acrylic esters having a hydroxy functionality are termed "hydroxy-functional

(Meth) acrylic acid ester ".

The term "polyurethane (meth) acrylate" in the context of this invention denotes a polyurethane whose free terminal isocyanate groups have been reacted with a nucleophilic functionalized (meth) acrylate ester. The isocyanate groups react with the nucleophilic group of the nucleophilic functionalized (meth) acrylic ester, eg. As hydroxy, amino or mercapto groups, and there are formed terminal ethylenically unsaturated functionalities derived from (meth) acrylates. The term (meth) acrylic acid refers herein to methacrylic acid, acrylic acid and mixtures of these acids. Because the nucleophilically functionalized (meth) acrylic acid esters react with the free isocyanate groups of the polyurethane, ie they "cap" them, they are also referred to as "capping reagents" or "capping reagents".

The term "reactive diluent" is understood according to the invention to mean a substance which contains at least one ethylenic double bond. Of the

Reactive diluent fulfills the following functions:

1) The reactive diluent serves as a liquid reaction medium for the reaction of polyisocyanate with at least one polyol and a nucleophilically functionalized (meth) acrylic ester. The reactive diluent does not participate in the reaction mentioned. 2) After completion of the reaction described under 1), the reactive diluent is the liquid dispersant for the formed functionalized

Polyurethane (meth) acrylate particles.

3) The reactive diluent is in a further step by polymerization

curable, wherein at the end of the reaction, the previously formed

Polyurethane (meth) acrylate particles are embedded in the cured reactive diluent.

The product obtained after completion of step 3) is also referred to as "cured dispersion" in the context of this invention.

The embedding of the polyurethane (meth) acrylate particles in the cured

Dispersion takes place by copolymerization of the terminal, ethylenically unsaturated functionalities of the particles into the macromolecules of

polymerized matrix, where "polymerized matrix" is to be understood as the polymerized reactive diluent.

In the context of the present invention, the reactive diluent is not subject to any relevant restrictions, with the exception that it should as far as possible have no functional groups reactive toward polyisocyanates.

Suitable reactive diluents are listed, for example, in DE 10 2005 035 235 A1 in [0031].

In the context of the present invention, it has proved to be favorable if the reactive diluent comprises a polyfunctional (meth) acrylate. It is preferred if this polyfunctional methacrylate is a difunctional (meth) acrylate. Particularly suitable di (meth) acrylates in this context are the di (meth) acrylates of propanediol, butanediol, hexanediol, octanediol, nonanediol, decanediol and eicosanediol. Further suitable difunctional (meth) acrylates are the di (meth) acrylate of ethylene glycol,

Diethylene glycol, triethylene glycol, tetraethylene glycol, Dodekaethylenglykols, Tetradekaethylenglykols, propylene glycol, dipropylene glycol and

Tetradecapropylene glycol and glycerol di (meth) acrylate, 2,2'-bis [p- (y-methacryloxy-β-hydroxypropoxy) phenylpropane] or bis-GMA, bisphenol A dimethacrylate, neopentyl glycol di (meth) acrylate, 2,2'-di (4-Methacryloxypolyethoxyphenyl) propane having from 2 to 10 ethoxy groups per molecule and 1,2-bis (3-methacryloxy-2-hydroxypropoxy) butane. Suitable tri- or polyfunctional (meth) acrylates are for example the

Trimethylolpropane tri (meth) acrylate and the pentaerythritol tetra (meth) acrylate.

As reactive diluents it is also possible to use polar monomers, for example those having hydroxyl groups, to improve the adhesion. It should be noted, however, that monomers containing, for example, hydroxyl groups can react with isocyanates reactions. Therefore, such monomers can be added to the dispersion only after the polyaddition step. Suitably, the amount of such polar monomers is limited to the

Sensitivity to water swelling should not be unnecessarily increased. Particular preference is given to polar, in particular hydroxyl-containing, monomers which are not covalently bound to the polyurethane (meth) acrylate particles and are therefore to be distinguished in their function from the nucleophilicly functionalized (meth) acrylic acid esters in amounts of not more than 0.1 to 20% by weight. -%, based on the total weight of the reactive diluent used. As explained above, however, it is preferred if in the coating compositions according to the invention no such monomers are contained as constituents of the reactive diluent.

In the context of the present invention, it is expedient if the proportion of polyfunctional (meth) acrylates is at least 20% by weight, in particular

at least 30% by weight, preferably at least 40% by weight, more preferably at least 50% by weight, even more preferably at least 70% by weight and most preferably at least 90% by weight, based on the weight of the

Reaktivverdünners, amounts. In a preferred embodiment, the reactive diluent consists exclusively of polyfunctional (meth) acrylates, more preferably exclusively of difunctional (meth) acrylates.

A reactive diluent based on (meth) acrylates may further

Containing comonomers which are copolymerizable with (meth) acrylates. These include, but are not limited to, vinyl esters, vinyl chloride, vinylidene chloride, vinyl acetate, styrene, substituted styrenes having an alkyl substituent in the side chain such as α-methylstyrene and α-ethylstyrene, substituted styrenes having an alkyl substituent on the ring such as vinyltoluene and p-methylstyrene , halogenated styrenes, such as monochlorostyrenes, dichlorostyrenes,

Tribromostyrenes or tetrabromostyrenes, vinyl and isoprenyl ethers,

Maleic acid derivatives, such as maleic anhydride,

Methylmaleic anhydride, maleimide, methylmaleimide, phenylmaleimide and Cyclohexylmaleimide, and dienes such as 1,3-butadiene, divinylbenzene, diallyl phthalate and 1,4-butanediol divinyl ether.

The proportion of the abovementioned comonomers is 40% by weight of the

Reactive thinner limited, otherwise the mechanical properties of the cured dispersion can be adversely affected. The proportion of vinylaromatics here is limited to 30% by weight of the reactive diluent, since higher proportions can lead to segregation of the system and thus turbidity.

The reactive diluent is accordingly particularly preferred

0 to 40 parts by weight of monofunctional (meth) acrylate,

- 0 to 40 parts by weight of comonomer and

- Made up 60 to 100 parts by weight of polyfunctional (meth) acrylate.

Polyisocyanates in the context of the present invention

low molecular weight compounds containing two or more isocyanate groups in the molecule. Preference is given to using diisocyanates in the present invention.

In certain embodiments, polyisocyanates having three or more isocyanate groups may additionally be added. By selecting the proportion of polyisocyanates having three or more isocyanate groups can be the

Set property spectrum of elongation at break and tear strength. The higher the proportion of compounds having three or more functionalities, the greater the tensile strength. Here, however, the elongation at break decreases sharply.

Accordingly, it has been found that the proportion of polyisocyanates having three or more functionalities should not be greater than 10% by weight, preferably not more than 5% by weight, based on the total weight of polyisocyanates.

In the context of the present invention, suitable polyisocyanates are

For example, in DE 10 2005 035 235 AI called. In the context of the present invention, however, it is preferred that in the

Polyurethane (meth) acrylate particles to be included is an aliphatic isocyanate such as 4,4'- and 2,4'-methylenedicyclohexyl diisocyanate, hexamethylene diisocyanate or isophorone diisocyanate (IPDI). Most notably Preferably, the polyisocyanate is a cycloaliphatic polyisocyanate, such as

Isophorone.

Suitable polyisocyanates can also be obtained, for example, by reacting polyhydric alcohols with diisocyanates or by the polymerization of diisocyanates. Furthermore, polyisocyanates are also used

can be used, which can be represented by reacting hexamethylene diisocyanates with small amounts of water. These products contain biuret groups. All mentioned isocyanates can be used individually or as a mixture.

As stated above, the isocyanate is reacted with at least one polyol. A polyol is understood in the context of the present

Invention a compound having at least two hydroxy functionalities. The polyol may have a uniform molecular weight or a statistical distribution of molecular weight.

The polyol is preferably a high molecular weight polyol having a statistical molecular weight distribution. In this sense, a "high molecular weight polyol" in the present invention means a polyol having two or more hydroxy groups, wherein the weight average molecular weight of the high molecular weight polyol is in the range of> 500 to about 20,000 g / mol. It is preferably in the range of> 500 to 15,000 g / mol,

Suitably in the range of> 500 to 10,000 g / mol and especially

preferably in the range of> 500 to 5,000 g / mol, measured with

Gel permeation chromatography (GPC).

Exemplary of high molecular weight polyols are the polyether polyols. An example of polyether polyols are polyalkylene ether polyols of the structural formula

wherein the substituent R is hydrogen or a lower alkyl group of 1-5 carbon atoms, including mixed substituents, n

typically 0-6 and m can be 2 to 100 or higher. Includes the poly (oxytetramethylene) glycols (= polytetramethyleneetherglycol =

Polytetrahydrofuran), poly (oxyethylene) glycols, poly (oxy-l, 2-propylene) glycols and the reaction products of ethylene glycol with a mixture of 1,2-propylene oxide, ethylene oxide and alkyl glycidyl ethers.

A particularly preferred polyol is polytetrahydrofuran. It is available, for example, from BASF under the trade names ®PTH F 650 or ®PTH F 2000. A very particularly preferred polyol in the context of the invention is ®PTH F 2000.

Polyether polyols having at least three hydroxyl functionalities can also be used. In order to obtain at least three hydroxyl functionalities which can react with isocyanate groups, it is possible to use, for example, alcohols which are at least three starting molecules

Have hydroxyl groups. These include glycerol,

Trimethylolpropane, erythritol, pentaerythritol, sorbitol and inositol, of which glycerol is preferred. A preferred trifunctional polyol is a trifunctional polypropylene ether polyol of propylene oxide, ethylene oxide and glycerine. Such a polyol is marketed under the name Baycoll® BT 5035 by Bayer.

As high molecular weight polyols also copolyester diols, d. H. linear copolyesters terminated by primary hydroxyl groups. Their weight-average molecular weight, determined by means of GPC, is preferably 3000-5000 g / mol. They are obtainable by esterification of an organic polycarboxylic acid or a derivative thereof with organic polyols and / or an epoxide. In general, the polycarboxylic acids and polyols are aliphatic or aromatic dibasic acids and diols.

As the diol in the copolyester diol, alkylene glycols such as

Ethylene glycol, neopentyl glycol, or glycols such as bisphenol A,

Cyclohexanediol, cyclohexanedimethanol, caprolactone-derived diols, e.g. As the reaction product of ε-caprolactone and ethylene glycol, hydroxy-alkylated

Bisphenols, polyether glycols such as poly (oxytetramethylene) glycol and the like used. Polyols of higher functionality can also be used. They include, for example, trimethylolpropane, trimethylolethane, pentaerythritol, and higher molecular weight polyols, such as those made by oxyalkylation of low molecular weight polyols. As the acid component in the copolyester diol, it is preferable to use monomeric carboxylic acids or anhydrides having 2 to 36 carbon atoms per molecule. Usable acids are z. Phthalic acid, isophthalic acid,

Terephthalic acid, tetrahydrophthalic acid, decanedioic acid, dodecanedioic acid. The polyesters may contain small amounts of monobasic acids, such as. B.

Benzoic acid, stearic acid, acetic acid and oleic acid. Also usable are higher polycarboxylic acids, such as trimellitic acid. Medium-long copolyester diols preferred according to the invention are marketed by Degussa under the trade names DYNACOLL® 7380 and DYNACOLL® 7390.

Also preferred in the present invention are copolyesters having a molecular weight Mw, determined by GPC, of about 5500 and a

Hydroxyl number from 18 to 24. A corresponding polymer is available, for example, from Evonik under the trade name DYNACOLL® 7250.

In a particularly preferred embodiment, the reaction mixture is used to form the polyurethane (meth) acrylate particles in addition to a

high molecular weight polyol also added a low molecular weight polyol. Accordingly, in a highly preferred embodiment

Polyurethane (meth) acrylate particles obtainable by reacting a polyisocyanate with a high molecular weight polyol, a low molecular weight polyol and a hydroxyalkyl (meth) acrylic ester in the reactive diluent.

A "low molecular weight polyol" is understood according to the invention to mean a compound which has two or more hydroxyl functionalities and a molar mass of 50-500 g / mol, preferably 50-250 g / mol. The molecular weight may be uniform or, in the case of a polymerization product, it may be randomly distributed, in the latter case the molecular weight being the weight average molecular weight. Preferred as a low molecular weight polyol is one with a uniform

Molecular weight, wherein the aliphatic diols having 2 to 18 carbon atoms, such as. Ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,4- Butanediol, 1,2-hexanediol and 1,6-hexanediol, and the cycloaliphatic polyols, such as 1,2-cyclohexanediol and cyclohexanedimethanol, are particularly preferred. Likewise usable are the polyols with ether groups, such as diethylene glycol and triethylene glycol and dipropylene glycol. Exemplary of low molecular weight polyols having more than two hydroxy groups are trimethylolmethane,

Trimethylolethane, trimethylolpropane, glycerol and pentaerythritol. The most preferred low molecular weight polyols used are 1,4-butanediol and 1,3-propanediol. It is also possible to use low molecular weight polyols having a statistical molecular weight distribution. As a low molecular weight polyol having a statistical molecular weight distribution, in principle, any polyol which is composed of the same monomeric units as the above-described high molecular weight polyols, but a

correspondingly lower molecular weight, as stated above possesses. The skilled person is readily apparent that the weight average of

Molecular weight in the case of a low molecular weight polyol having a statistical molecular weight distribution will be predominantly in the vicinity of the upper limit of the previously defined range of 50-500 g / mol.

The low molecular weight polyol having a random distribution is preferably a trihydroxy-functional polyol, more preferably a trihydroxy-functional polyalkylene glycol, and most preferably a trihydroxy-functional polypropylene glycol. Such trihydroxy-functional polyalkylene glycols suitably have a KOH number in the range from 140 to 600, and preferably in the range from 360 to 500. A suitable trihydroxy-functional polyalkylene glycol is available, for example, as Desmophen 1380 BT from Bayer. The molar ratio of the hydroxy groups of the low molecular weight trihydroxy-functional polyalkylene glycols is based on the

Total molar amount of hydroxy groups from the high molecular weight polyols and the low molecular weight trihydroxy-functional

Polyalkylene glycols, preferably 2% to 30% and particularly preferably 4 to 20%. In the context of the invention, it is preferred if the polyol to be included in the polyurethane (meth) acrylate particles comprises at least one dihydroxy-functional and at least one trihydroxy-functional polyol. For the trihydroxy-functional polyol, it is again preferred if this comprises a polyalkylene glycol, preferably a polypropylene glycol. In the context of the present

It is particularly preferred if the polyol comprises a polyether diol having a weight average molecular weight of> 500 to 5000 g / mol and a polyether triol having a weight average molecular weight of> 50 to 500 g / mol, wherein the molar amount of OH Groups of the polyether triol having a weight average molecular weight of> 50 to 500 g / mol about 3 to 25%, preferably about 5 to 15%, the sum of the molar amount of the polyether diol having a weight average molecular weight of> 500 to 5000 g / mol and of the polyether triol having a weight average molecular weight of> 50 to 500 g / mol.

Particularly preferred nucleophilic functionalized (meth) acrylic esters are hydroxy-functional (meth) acrylic esters. A "hydroxy-functional (meth) acrylic acid ester" is understood according to the invention to mean a (meth) acrylic acid ester which, after esterification with (meth) acrylic acid, still carries at least one hydroxyl functionality in the residue derived from the alcohol. In other words, it is the ester of a (meth) acrylic acid and a diol or polyol, with diols being preferred.

A particularly preferred group of "hydroxyfunctional (meth) acrylic acid esters" are the hydroxyalkyl (meth) acrylic acid esters. Hydroxyalkyl (meth) acrylates which can be used according to the invention are esters of (meth) acrylic acid with dihydric, aliphatic alcohols. These compounds are well known in the art. You can, for example, by the reaction of

(Meth) acrylic acid can be obtained with oxiranes.

The oxirane compounds include, but are not limited to, ethylene oxide, propylene oxide, 1,2-butylene oxide and / or 2,3-butylene oxide, cyclohexene oxide, styrene oxide,

Epichlorohydrin and glycidyl ester. These compounds can be used both individually and as a mixture.

The hydroxyalkyl (meth) acrylic acid esters can also contain substituents, such as, for example, phenyl radicals or amino groups. Preferred hydroxyalkyl (meth) acrylic esters include 1-hydroxyethyl acrylate, 1-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate (H EA), 2-hydroxyethyl methacrylate (H EMA), 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl acrylate , 3-hydroxypropyl methacrylate, 6-hydroxyhexyl acrylate and 6-hydroxyhexyl methacrylate, 3-phenoxy-2-hydroxypropyl methacrylate, acrylic acid (4-hydroxybutyl ester), methacrylic acid (hydroxymethylamide), caprolactone hydroxyethyl methacrylate and caprolactone hydroxyethyl acrylate. Of these, the hydroxyethyl methacrylates, the hydroxyethyl acrylates, 2-hydroxypropyl methacrylate and 2-hydroxypropyl acrylate are very particularly preferred. Most preferred are 2-hydroxyethyl methacrylate and 2-hydroxyethyl acrylate.

Another preferred group of hydroxyfunctional (meth) acrylic esters are the polyether methacrylates. These are substances which are obtained by esterification of a (meth) acrylic acid with a polyether polyol, preferably a polyether diol. Such polyether polyols have already been mentioned above in the mention of preferred polyols. In the polyether methacrylates, the hydroxyalkyl radical of the ester contains polyoxyalkylene groups, which may be both linear and branched, such as polyethylene oxide, polypropylene oxide and polytetramethylene oxide. These groups often have between 2 and 10 oxyalkylene units. Specific examples are polyethoxy methacrylate, polypropoxymethacrylate, polyethylene oxide / polytetramethylene oxide methacrylate, polyethylene oxide / polypropylene oxide methacrylate. The amount of nucleophilically functionalized (meth) acrylic acid ester is chosen so that free isocyanate groups, which are still present after the polycondensation between polyisocyanate and polyol, are completely reacted. To determine the optimum amount of nucleophilically functionalized (meth) acrylic acid esters, the content of free isocyanate groups can be determined after the polycondensation. The determination of the content of free isocyanate groups can be carried out, for example, by infrared spectroscopic methods or by titration.

The polyurethane (meth) acrylate from which the particles of the dispersion according to the invention are synthesized generally has a weight-average molecular weight of from 3,000 to 600,000 g / mol, preferably from 3,000 to 500,000 g / mol, which with the aid of GPC determine is. In the dispersion according to the invention, the polyurethane (meth) acrylate particles have an average diameter of less than 40 nm, whereby the desired transparency is achieved. Preferably, a mean particle diameter of less than 20 nm is achieved, more preferably less than 10 nm.

The specified diameters can be determined by means of light scattering. Corresponding methods are readily familiar to the person skilled in the art. A suitable device for determining the particle size is for example the

Nanosizer from Malvern.

For the purposes of the present invention, the solids content is to be understood as meaning the weight of the polyurethane (meth) acrylate particles, based on the weight of the entire dispersion. In the dispersion according to the invention, the solids content is preferably at least 20% by weight. It is also preferable that the solid content is 80% by weight or less. Particularly preferred is a solids content of 30 to 50 wt .-% and most preferably 35 to 45 wt .-%, each based on the total weight of the dispersion.

In principle, any initiator with which a polymerization of the reactive diluent is possible can be used as initiator for the polymerization of the reactive diluent in the context of the present invention. Examples of suitable initiators are, for example, peroxides and hydroxy peroxides, such as dibenzoyl peroxide, diacetyl peroxide and t-butyl hydroperoxide. Another class of initiators are heat-activated initiators, especially azo initiators, such as azobisisobutyronitrile. If a peroxide is used as the initiator, its decomposition can be induced by means of promoters at low temperatures. A particularly preferred promoter in this context is N, N-bis- (2-hydroxyethyl) -p-toluidine (DEPT). The initiator used in the context of the present invention is preferably a UV-activatable photoinitiator. Such photoinitiators typically distinguish between Norrish Type I and Norrish Type II photoinitiators. Particularly preferred in the context of the present invention

Photoinitiators are those of the Norrish type I. Examples of such

Photoinitiators are the 2-hydroxy-2-methyl-1-phenyl-propane-1-one (available under the name Darocure® 1173 from Ciba) or the 1-hydroxycyclohexyl phenyl ketone, which is mixed with benzophenone (1: 1) as Irgacure® 500 from Ciba is available. The amount of photoinitiator added is not substantially limited, but should be 10% by weight based on the amount of

Total weight of the paint composition, do not exceed, otherwise an influence on the properties of the paint composition can not be excluded. Preferred levels of the photoinitiator are in the range of about 1 to 6 wt%, and more preferably about 2 to 4.5 wt%.

In addition to the constituents described above, the coating composition according to the present invention may also contain suitable additives, in particular in the form of defoamers, solvents and / or film formers. A suitable defoamer is, for example, Byk 141 from Byk. Defoamers are usually effective even in small amounts, so the content of

Defoamers in the paint composition of the invention should not exceed 3%. With respect to the defoamer, a content in the range from 0.5 to 1% by weight, based on the total weight of the coating composition, is preferred.

Furthermore, the paint composition may contain a solvent, such as in particular butyl acetate. Also, with respect to the amount of the solvent, the paint composition is not substantially limited, but it is desirable to use the solvent in amounts not exceeding 50% by weight based on the total weight of the paint composition. In one embodiment, the coating composition according to the invention is free of solvents. In another embodiment, the coating composition according to the invention contains from 20 to 50% by weight, in particular from 30 to 50% by weight.

Solvent, preferably in the form of butyl acetate. Depending on the application process, the use of organic solvents may be desired, so that the

Processing parameters such. As viscosity, wet / dry film thickness and paint course can be adapted to user requirements. The preferred application methods are z. As doctoring, rolling, casting, Vakuumat method, dipping, drumming, spraying (cup gun, airless, Airmix).

Furthermore, it may be expedient to add film formers to the coating composition according to the invention. Suitable film formers are, for example

Cellulose derivatives. Particularly suitable film formers are cellulose esters,

in particular cellulose acetobutyrate. Other suitable film formers are z. B. high molecular weight, partially hydrolyzed polyvinyl chloride / vinyl acetate resins (eg., Copolymers of the brand UCAR ™ VAGH Fa. Dow Chemical Company). The viscosities of the coating compositions according to the invention are generally between 50 and 1000 mPa.s, measured rheologically with a conical plate geometry at a shear rate of 100 s ^"1 and T = 25 to 26 ° C.

Preferably, the viscosity is between 50 and 500 mPa.s, more preferably about 80 to 300 mPa.s, and most preferably about 100 to 250 mPa.s. s. The "paint expert" also speaks of the flow time in seconds which is determined using a flow cup in accordance with DIN 53211. According to DIN 53211, only one flow cup with a discharge nozzle of 4 mm diameter is standardized

Flow time of approx. 25 - 250 s, preferably between 30 - 180 s.

In a further embodiment, the present invention also relates to a nonaqueous transparent dispersion of polyurethane (meth) acrylate particles in specific reactive diluents obtainable by reacting

Polyisocyanate with at least one polyol and one nucleophile

functionalized (meth) acrylic acid ester in these reactive diluents. The special reactive diluents include methyl methacrylate (MMA),

Isobornyl acrylate (IBOA), hexanediol diacrylate (H DDA), dipropylene glycol diacylate and tripropylene glycol diacrylate. Such dispersions are transparent and remain transparent even after curing of the reactive diluent. This dispersion can be cured in addition to a use as a paint for the formation of an adhesive bond or a casting. Except for a curing initiator no further substances have to be added. Of course, it is possible, the dispersion of the invention in conventional formulations of adhesive systems, paints, coatings or molding compounds, as described in part above, mix and then cure the formulation.

As reactive diluents, in the context of the above-described aspect of the present invention, as mentioned above, methyl methacrylate,

Isobornyl acrylate and hexanediol diacrylate or dipropylene glycol diacrylate or tripropylene glycol diacrylate and low molecular weight (multifunctional)

Use polyether acrylates. However, it is also possible (meth) acrylates such as 2- Use ethylhexyl acrylate or tetrahydrofurfuryl methacrylate as a reactive diluent. In addition, come as reactive diluents in the DE

102005035235 AI listed in [0031] into consideration. The polyisocyanates usable in the above aspect of the present invention include, in particular, tetramethylene diisocyanate (TM DI), tolylene diisocyanate (TDI) and isophorone diisocyanate (IPDI).

In a particularly preferred embodiment of a nonaqueous one

transparent dispersion according to the above-described aspect, the polyurethane (meth) acrylate particles are available from tetramethylene diisocyanate as a polyisocyanate, a copolyester having a molecular weight of about 5,500 and a hydroxyl number of 18 to 24 and 1,4-butanediol as polyols, and from hydroxyethyl methacrylate as nucleophilically functionalized (meth) acrylate. The reactive diluent in this case is preferably methyl methacrylate. It is very particularly preferred if the dispersion is based on polyurethane particles which consist of about 6% by weight of polymethylene diisocyanate, about 46% by weight of the

Copolyesters having a Mw of 5,500 and a hydroxyl number of 18 to 24, about 1 wt .-% 1,4-butanediol and about 4 wt .-% hydroxyethyl methacrylate are available, and 43 wt .-% methyl methacrylate as a reactive diluent based. in the

The term "about" above and below encompasses a range of ± 1% by weight, preferably ± 0.5% by weight. The weights are in each case based on the total weight of the dispersion. In an alternative preferred embodiment according to the above-described aspect, the nonaqueous transparent dispersion is based on polyurethane particles of tolylene diisocyanate as polyisocyanate,

Polytetrahydrofuran having an average molecular weight of about 2,000 as a polyol, and hydroxyethyl acrylate as a nucleophilic functionalized

(Meth) acrylic acid ester and isobornyl acrylate as a reactive diluent. For this purpose, it is again preferred if the dispersion is based on polyurethane particles n which comprise about 4% by weight of tolylene diisocyanate, about 27% by weight of the polytetrahydrofuran having an average molecular weight of about 2000 and about 4% by weight.

Hydroxyethyl acrylate are available, and about 65 wt .-% isobornyl acrylate is based as a reactive diluent. In a further preferred embodiment according to the above-described aspect, the nonaqueous transparent dispersion is based on polyurethane particles of isophorone diisocyanate as polyisocyanate, a mixture of polytetrahydrofuran having an average molecular weight of about 2000 and 1,4-butanediol as polyol and hydroxyethyl acrylate as nucleophilically functionalized (meth) acrylic ester and hexanediol diacrylate as a reactive diluent. For this purpose, it is again preferred if the dispersion is based on polyurethane particles which consist of about 12% by weight of isophorone diisocyanate, about 28% by weight of the polytetrahydrofuran having an average molecular weight of about 2000, about 2% by weight of 1,4-butanediol, and about 4% by weight of hydroxyethyl acrylate, and about 54% by weight of hexanediol diacrylate is a reactive diluent.

In the embodiment described above, the polyol may optionally additionally contain trimethylolpropane or a trihydroxy-functional polypropylene glycol having a KOH number of about 385 mg KOH / g. For such mixtures, it is preferred if the molar amount of the OH groups from the trimethylolpropane or the trihydroxy-functional polypropylene glycol about 5 to 15% of the sum of the molar amount of OH groups of polytetrahydrofuran having an average molecular weight of about 2000 and the trimethyolpropane or the

trihydroxy-functional polypropylene glycol.

In a further aspect, the invention relates to a production method for the coating composition described above. In this process, a polyisocyanate is reacted in a stirred tank with at least one polyol and a nucleophilically functionalized (meth) acrylic ester in a reactive diluent. These ingredients have been previously described in detail. The coating composition according to the invention is then obtainable by adding to the reaction mixture, before or after polymerization of the polyisocyanate, an initiator. A suitable process for the preparation of polyurethane (meth) acrylate particles is described, for example, in DE 10 2005 035 235 A1 in [0098] to [0112].

described.

Another aspect of the present invention relates to a coated

Substrate by applying one as described above

Paint composition on the substrate and curing of the composition on the substrate is available. The substrate is expediently glass, metal, preferably with a surface of aluminum, zinc or iron, and Plastics, preferably of PVC or polycarbonate. If, in the foregoing, metals having a surface of aluminum, zinc or iron are mentioned, this means that the surface, with the exception of unavoidable

Oxydationsprodukten of aluminum, zinc or iron, consisting essentially of elemental aluminum, zinc or iron.

Another aspect of the present invention relates to a method for

Preparation of a coated substrate, comprising applying a coating composition as described above to a substrate and curing the coating composition on the substrate. It is preferred if the curing of the composition takes place under irradiation with UV light, which implies that the initiator used is a UV-light-activatable initiator.

In the cured state, as mentioned above, the paint composition of the present invention has not only high transparency but also good transparency

Adhesive strength, especially on substrates such as glass, metals or plastics, as well as a high hardness and resistance to micro-scratches.

The above-described dispersions of polyurethane (meth) acrylate particles in specific reactive diluents can also be processed into shaped articles, so that a further aspect of the present invention relates to shaped articles which have been produced from corresponding dispersions.

The invention is illustrated below by examples, which should not be construed as limiting the inventive idea.

Examples Preparation of Polyurethane / Reactive Thinner Dispersions

Component II (cf., Tables 1 to 10 below) was added at 60 ° C. to component I in a dropping funnel heated to 60.degree

Dropped glass reactor and stirred at a stirring speed of 14.9 m / s. Subsequently, the catalyst (component III, dibutyltin dilaurate) was added to the reaction mixture and stirred for 1 hour at a stirring rate of 14.9 m / s stirred. The resulting mixture was finally added with Component IV and the mixture was cooled to 23 ° C.

The compositions of the various approaches are given in Tables 1 to 10 below.

Table 1: Lacquer base 1

Component Substance Quantity [g]

I IPDI 58,29

HDDA 170.32

II PTHF 2000 140.76

1,4-butanediol 7,49

HDDA 100.45

III DBTDL 0.44

IV HEA 22:18

Table 2: Lacquer base 2

Component Substance Quantity [g]

I IPDI 59,17

HDDA 172.29

II PTHF 2000 135,28

1,4-butanediol 7,58

HDDA 101,44

Desmophen 1380 BT 1.04

III DBTDL 0.44

IV HEA 22.74 Table 3: Lacquer base 3

Component Substance Quantity [g]

I IPDI 59.90

HDDA 174.41

II PTHF 2000 129.73

1,4-butanediol 7,67

HDDA 102.68

Desmophen 1380 BT 2,11

III DBTDL 0.46

IV HEA 23:02

Table 4: Lacquer base 4

Component Substance Quantity [g]

I IPDI 60.64

HDDA 176.58

II PTHF 2000 124.06

1,4-butanediol 7,76

HDDA 103.96

Desmophen 1380 BT 3.21

III DBTDL 0.47

IV HEA 23,31

Table 5: Lacquer base 5

Component Substance Quantity [g]

I IPDI 60,92

HDDA 177.38

II PTHF 2000 124.61

1,4-butanediol 7,80

HDDA 104.43

Trimethylolpropane 0.98

III DBTDL 0.47

IV HEA 23:42 In addition, two compositions were prepared containing methyl methacrylate (MMA) or isobornyl acrylate (IBOA) in place of H DDA.

Table 6

The dispersions prepared according to the formulations from Tables 6 and 7 were clear, colorless liquids.

The various lacquer base compositions were formulated into coatings for peel strength tests, the compositions of which are given in Table 8 below: Table 8

The adhesion of the paint formulations of the invention and a

Comparative paint 1 based on Desmolux 2740 on different substrates was tested in accordance with DIN EN ISO 2409 (characteristic value ISO GT0 - GT5). GT0 stands for very good adhesion, GT5 for complete delamination / poor adhesion. The results of these studies are shown in Table 9 below. Table 9

Of the overall performance (adhesion), Paint 1 shows the best results. Comparative 1 based on Desmolux 2740 shows the worst results in this series of experiments. There are tendencies recognizable that with increasing polyol content (trifunctional), the adhesive strengths are slightly less favorable (paints 2 to 5). It is further shown that all paint formulations according to the invention, paint 1 to paint 5, exhibit improved adhesive strengths on all the substrates investigated in comparison with the commercially available product based on Desmolux 2724. The best bond strengths could be determined for the formulation Lack 1. All paints according to the invention, paint 1 to paint 5, show very high adhesive strengths on polycarbonate sheets and PVC films.

From the formulations varnish 1 to varnish 5 and comparative varnish 1, the pendulum damping in seconds according to König (determined in accordance with DIN 53157 with 100 pm wet application) was furthermore determined. The results of these tests are shown in the following Table 10 as oscillation time in seconds: Table 10

In the investigations, the lowest pendulum attenuation values were found in the formulations Lack 1 and Lack 4, whereby the pendulum attenuation values in the paint series Lack 2 to Lack 4 decrease with increasing content of trifunctional polyol.

Furthermore, the resistance of a coating formulation according to the invention against micro-scratching was determined. The tested formulations are shown in Table 11 below.

Table 11

For a comparative test, varnish 6 (diol) and comparison varnish 2 based on Desmolux 2740 were investigated.

In the following, the resistance to micro-scratches was determined according to the IH D factory standard W-466. This standard applies to furniture surfaces and serves to uniformly determine the resistance of the top lacquer layer to micro-scratches. The test was carried out with a mini Martindale device. The Test specimens were subjected to 5 Lissajous movements (the Lissajous movement corresponds to 16 cycles of defined Reibtellerbewegungen according to methods A and B according to IH D-Werksnorm 466). As a friction agent, the Scotch-Brite friction materials 7447 (very fine) and 7448 (ultrafine) were used. The test was carried out with a test force of 6 N according to method A (evaluation by determination of the gloss change). The investigations provided the results shown in Table 12.

Table 12:

Lacquer 6 and the comparison lacquer 2 based on Desmolux 2740 show a comparably low gloss change of 10.5% and 6.3%, respectively.

# # #

Claims

claims

Coating composition in the form of a nonaqueous transparent dispersion comprising

- a reactive diluent

Polyurethane (meth) acrylate particles which are obtainable by reacting at least one polyisocyanate with at least one polyol and at least one nucleophilically functionalized (meth) acrylic ester in the reactive diluent to give polyurethane (meth) acrylate particles having an average diameter of less than 40 nm, and

- an initiator.

Paint composition according to claim 1, characterized in that the reactive diluent comprises a polyfunctional (meth) acrylate, preferably a difunctional (meth) acrylate.

Paint composition according to claim 1 or 2, characterized in that the at least one in the polyurethane (meth) acrylate particles

to be included polyisocyanate comprises an aliphatic polyisocyanate, preferably a cycloaliphatic polyisocyanate.

Paint composition according to any one of claims 1 to 3, characterized in that the at least one polyol to be included in the polyurethane (meth) acrylate particles comprises at least one dihydroxy-functional and at least one trihydroxy-functional polyol.

Paint composition according to claim 4, characterized in that the trihydroxy-functional polyol is a polyalkylene glycol, preferably a

Polypropylene glycol.

A coating composition according to any one of the preceding claims, characterized in that the at least one polyol comprises a polyether diol having a weight average molecular weight of> 500 to 5000 g / mol and a polyether triol having a weight average molecular weight of> 50 to 500 g / mol, the Mol amount of OH groups from the

Polyether triol having a weight average molecular weight of> 50 to 500 g / mol about 3 to 25%, preferably about 5 to 15%, the sum of the molar amount of the polyether diol having a weight average molecular weight of> 500 to 5000 g / mol and of the polyether triol having a weight average molecular weight of> 50 to 500 g / mol.

7. Paint composition according to one of the preceding claims, characterized in that the proportion of polyurethane (meth) acrylate 30 to 50 wt -.%, Preferably 35 to 45 wt -.%, Based on the total weight of the dispersion.

8. Paint composition according to one of the preceding claims, characterized in that the initiator is a UV-activatable photoinitiator, in particular of the Norrish type I. 9. Paint composition according to one of the preceding claims, characterized in that the composition contains at least one additive selected from defoamers, solvents and film formers.

10. Paint composition according to claim 9, characterized in that the film-forming agent comprises a cellulose derivative, preferably a cellulose ester and more preferably cellulose acetobutyrate.

Paint composition according to one of the preceding claims, characterized in that the composition has a viscosity in the range from 50 to 500 mPas, preferably from 80 to 300 mPas, and particularly preferably from 100 to

250 mPas, wherein the viscosity rheologically with a

Cone-plate geometry is to be determined at a shear rate of 100 s ^-1 and T = 25 to 26 ° C. A coated substrate obtainable by applying a paint composition as described in any of claims 1 to 11 to the substrate and curing the composition on the substrate ,

13. Coated substrate, characterized in that the substrate glass, metal, preferably with a surface of aluminum, zinc or iron, and

Plastic, preferably PVC or polycarbonate, includes.

14. A method for producing a coated substrate comprising

Applying a paint composition as described in any one of claims 1 to 11 to a substrate and

- curing the paint composition on the substrate.

15. The method of claim 14, wherein the curing of the composition is carried out under irradiation with UV light.