MXPA99010681A - New uretanoacrilates, procedure for its preparation as well as its - Google Patents

Abstract

The present invention relates to: New urethanoacrylates, to the process for their preparation as well as to their use as a component of coating compositions that harden under the influence of energy-rich radiation

Description

New urethanoacrylates. PROCESS FOR PREPARING THOROUGHLY AND ITS PREVIOUS USE OF THE INVENTION: The present invention relates to new urethanoacrylates, to the process for their preparation as well as to their use as a component of coating compositions that harden under the influence of energy-rich radiation. Urethane acrylates are known as coating agents that harden under the influence of energy-rich radiation. An overview is found in P..K.T. Oldring (Ed.), Chemistry & Technology of UV & EB Formulations For Coatings, Inks & Paints, Vol. 2, 1991, SITA Technology, London, 'pp. 73-123. Urethane-acrylates are very valuable coating agents for substrates such as wood, metal, plastic and mineral substrates, for the preparation of urethane-acrylates the most different polyisocyanates can be used. They are used for the preparation of the urethane acrylates (cyclo) aliphatic polyisocyanates Although, among others, in DE-A 21 15 373 hexamethylene diisocyanate is also mentioned as a suitable diisocyanate, it can be said that in this case it is a purely hypothetical communication, since this diisocyanate in the formulations described in this publication, due to REF .: 31852 tendency to the crystallization of the uretanoacrylates that are formed, which precludes a use as a binder of lacquers, which must be liquid under normal conditions, not can be used In DE-A 4 027 743 modified urethanoacrylates are described with this Hexamethylene diisocyanate based alcohols that are liquid after preparation at room temperature. At temperatures below 10 ° C, these become cloudy with high to medium viscosity products. It is known from DE-A 42 32 013 that the following steps are intended to reverse the crystallization of urethane acrylates based on hexamethylene diisocyanate: partial use of other diisocyanates, eg isophorone diisocyanate, incorporation of alcohol components having ester groups and incorporation of mono or "sterically demanding divalent alcohols with branched molecular structure. All these measures strongly limit the possibilities of preparation and therefore also the possible variation of other properties, resulting in most of the time costs of the highest raw materials. Partially, reaction products of hexamethylene diisocyanate are also used as more functionalized polyisocyanates. Thus, for example, DE-A 37 37 244 describes urethane acrylates based on polyisocyanates containing isocyanurate groups. The greater functionalization leads to better stability properties of the hardened film. However, the crystallization tendencies of these products are still greater than that of urethane-acrylates based on hexamethylene diisocyanate itself. The object of the invention has therefore been to provide new low viscosity urethane acrylates which are resistant to yellowing and which, at temperatures below 10 ° C, do not exhibit any tendency for crystallization and reaction products of polyisocyanates containing functionalization greater than 2. Surprisingly it has been found that the use of polyisocyanates of the structural type of iminooxadiazinedione leads to urethanoacrylates having a substantially lower tendency to crystallization. Coating agents that harden "under the influence of energy-rich radiation characterized in that the coating agents contain a reaction product of: a) trimers of isocyanates (mixtures) based on aliphatic or cycloaliphatic diisocyanates constituted by 20 to 100% by mole of structural type compounds of iminooxadiazinedione of formula A, (TO), wherein R1, R2 and R3 represent, independently of each other (cyclo) optionally branched C4-C20 alkyls, and X represents identical or different isocyanate or isocyanate-modified radicals of the structural type of iminooxadiazinedione, isocyanurate, uretdione, urethane, allophanate, biuret or oxadiazinetrione and carrying on N the aforementioned radicals R1, R2 and R3, with b) a component alcohol containing at least one monovalent, optionally branched, C 1 -C 4 hydroxy-functional alkyl ester of (meth) acrylic acid. "Sodium% in moles" refers to the total amount of modified NCO products formed in the preparation of the isocyanate trimers (mixtures) from the isocyanate groups previously free from the starting diisocyanates.

Another object of the invention is a process for the production of the above-described coating agents by reacting an isocyanate-containing component with a hydroxyl-containing component, containing at least one monovalent hydroxy-functional ester of (meth) acrylic acid. in an NCO / OH equivalent ratio of 0.7: 1 to 1: 1, characterized in that the isocyanate-containing component is of the component A type. The invention also relates to the use of the coating compositions according to the invention. as a binder for coating compositions, in particular as a binder for lacquers curable by energy-rich radiation. Isocyanate trimers (mixtures) of component type a) which are used for the preparation of the coating compositions according to the invention are known from EP-A 798 299 or from German patent application DE-A 19 734 048.2 (Le A 32 514). Preferably, isocyanate trimers (mixtures) obtained by partial oligomerization of hexamethylene diisocyanate (HDI), 1,3-bis (isocyanatomethyl) cyclohexane (HeXDI) or isophorone diisocyanate are used.

(IPDI). In this respect, it is not important whether or not the starting diisocyanate to be oligomerized is completely separated from the reaction products following the partial oligomerization. Preferably, for the preparation of the coating compositions according to the invention, those isomers (trimmers) of the type of component a) having a dynamic viscosity at 23 ° C of 300 to 3,000 mPa.s are used, with particular preference for 500 to 1,500 mPa.s. Its NCO content is preferably from 15 to 30% by weight, particularly preferably from 20 to 25% by weight. The content of unreacted diisocyanate (starting material) is preferably less than 5.0% by weight, more preferably less than 1.0% by weight. The isocyanate trimers (mixtures) have a dynamic viscosity at 23 ° C, preferably from 500 to 2,000 mPa.s, particularly preferably from 1,000 to 1,500 mPa.s. Its NCO content is preferably from 15 to 30% by weight, particularly preferably from 20 to 25% by weight. The content of unreacted diisocyanate (starting material) is preferably less than 1.0% by weight, particularly preferably less than 0.5% by weight. The alcohol component according to b) contains at least one monovalent hydroxy functional ester of (meth) acrylic acid. This is to be understood as meaning an ester of acrylic acid or methacrylic acid with divalent alcohols having a free hydroxyl group, such as, for example, (meth) 2-hydroxyethyl, 2- or 3-hydroxypropyl (meth) acrylate or 2-, 3- or 4-hydroxypropyl esters. -hydroxybutyl, as well as discretional mixtures of such compounds. In addition, monovalent alcohols having (meth) acryloyl groups or reaction products composed substantially of such alcohols are also considered, which are obtained by esterification of n-valent alcohols with (meth) acrylic acid, mixtures of different alcohols can also be used as alcohols. , so that n represents a whole or fractional number as a statistical average of magnitude 2 to 4, preferably 3, and used per mole of the indicated alcohols of (n-0.8) to (nl, 2), preferably (nl) moles of (meth) acrylic acid. To these compounds or mixtures of products belong for example the reaction products of i) glycerin, trimethylolpropane and / or pentaerythritol, of low molecular weight alkoxylation products of such alcohols, such as, for example, ethoxylated or propoxylated trimethylolpropane, such as, for example, the addition product of ethylene oxide to trimethylolpropane of OH 550 or of discrete mixtures of such at least trivalent alcohols with divalent alcohols, such as for example ethylene glycol or propylene glycol with (ii) (meth) acrylic acid in the indicated molar ratio. These compounds have a molecular weight of 11 to 1,000, preferably of 116 to 750, and especially preferably of 116 to 158. As additional constituent of the alcohol component, mono or divyale alcohols containing ether and / or weight ester groups can optionally be used. molecular weight in the range of 100 to 300, preferably 130 to 200, with branched structure. Examples of these are 2,2-diethyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2-ethyl-1,3-hexanediol, 2,5-dimethyl-1,6-hexanediol. , 2, 2, 4-trimethyl-l, 3-pentanediol, (3-hydroxy-2, 2-dimethylpropyl) -3-hydroxy-2,2-dimethylpropionate as well as trimethylolpropanoformal. The reaction of the starting components a) and b) can be carried out in substances or in solvents which are inert towards isocyanates and hydroxyacrylates, such as, for example, acetone, 2-butanone, ethyl acetate, n-butyl acetate, low-weight esters. of (meth) acrylic acid, known to those skilled in the art under the term reactive diluents (described, for example, in PKT Oldring (Ed.), Chemistry & amp;; Technology of UV & EB Formulations For Coatings, Inks & Paints, Vol. 2, 1991, SITA Technology, London, p. 237-285) for hardening under energy-rich radiation, or in mixtures of such solvents, preferably maintaining at all reaction steps reaction temperatures of 20 to 100 ° C, particularly preferably 40 to 80 ° C. The starting components a) and b) and also the individual constituents of components a) and b) can be brought into the reaction in carrying out the process according to the invention in a discrete sequence. The NCO / OH equivalent ratio of components a) and b) ranges from 0.7: 1 to 1: 1, preferably from 0.9 to 1 to 0.95 to 1. In a preferred variant of the process component a) it is placed in a suitable reaction vessel and the component part b) comprising the hydroxy-functional ester of (meth) acrylic acid is first added and reacted at the temperatures indicated above until the NCO content corresponding to the most complete reaction possible of the hydroxy-functional ester of (meth) acrylic acid. The remainder is then added, given the present case of component b) which does not contain any ester of (meth) acrylic acid and is again reacted at the temperatures indicated above until the NCO content corresponding to the most complete reaction possible is reached. hydroxy-functional component. If component b) should contain a constituent which does not possess any ester of (meth) acrylic acid, then the preferred molar ratio relative to hydroxy groups between the constituents containing ester of (meth) acrylic acid and those lacking acid ester (meth) acrylic will be from 99: 1 to 7: 1, particularly preferably from 50: 1 to 10: 1. The reaction of components a) and b) can be catalyzed or not catalyzed. In the first mentioned case, this is preferably carried out in the presence of known catalysts of urethane chemistry, such as for example tin octoate (II), dibutyltin dilaurate or tertiary amines such as diazabicyclooctane. As a result of the reaction, products with an NCO content of less than 0.5% by weight, preferably less than 0.1%, are obtained In order to prevent premature unwanted polymerizations during the reaction and also during subsequent storage, it is advisable to add to the reaction mixture of 0.01 to 0.3% by weight, based on the total weight of the reactants, of polymerization inhibitors or antioxidants known per se Suitable additives of this type are described, for example, in "Methoden der Organischen Chemie" (Houben-Weyl), 4th edition, volume XIV / 1, pp. 433 ff., Georg Thieme Verlag, Stuttgart 1971. Examples are phenols, cresols and / or hydroquinones.

In a preferred variant of the process, a gas containing oxygen, preferably air, is passed through the reaction mixture to prevent unwanted polymerizations of the (meth) acrylates. The coating agents according to the invention can be used as a binder alone or mixed with other radiation-hardenable binders. Such binders are described, for example, in P.K.T. Oldring (Ed.), Chemistry & Technology of UV & EB Formulations For Coatings, Inks & Paints, Vol. 2, 1991, SITA Technology, London, p. 31-235. Examples which may be mentioned are urethane acrylates, epoxyacrylates, polyesteracrylates, polyether acrylates and unsaturated polyesters. In addition, the binders according to the invention can be used diluted with solvents. Examples of suitable solvents are acetone, 2-butanone, ethyl acetate, n-butyl acetate, methoxypropyl acetate or esters of low molecular weight (meta) acrylic acid. In the case of such mono-, di-oligoesters of (meta) acrylic acid, these are compounds known per se from coatings technology, which are referred to as reactive diluents and which, when curing, polymerize compounds can reduce the viscosity of the coating. unhardened lacquer. Such compounds are described in P.K.T. Oldring (Ed.), Chemistry & Technology of UV & EB Formulations For Coatings, Inks & Paints, Vol. 2, 1991, SITA Technology, London, p. 237-285.

Examples which may be mentioned are the esters of acrylic acid or methacrylic acid, preferably of acrylic acid, of the following alcohols. Monovalent alcohols are butanols, pentanols, hexanols, heptanols, octanols, nonanols and isomeric decanoles, in addition cycloaliphatic alcohols such as isobornyl, cyclohexanol and alkylated cyclohexanols, dicyclopentanol, arylaliphatic alcohols such as phenoxyethanol and nonylphenylethanol, as well as tetrahydrofurfuryl alcohols. In addition, alkoxylated derivatives of these alcohols can be used. Divalent alcohols are, for example, alcohols such as ethylene glycol, propanediol-1,2, propanediol-1,3, diethylene glycol, dipropylene glycol, isomeric butanediols, neopentyl glycol, hexanediol-1,6,6-ethylhexanediol and tripropylene glycol or alternatively alkoxylated derivatives of these alcohols. Preferred divalehte alcohols are hexanediol-1,6, dipropylene glycol and tripropylene glycol. Trivalent alcohols are glycerin or trimethylolpropane or their alkoxylated derivatives. Propoxylated glycerin is preferred. As polyvalent alcohols, alcohols such as pentaerythritol or ditrimethylolpropane or their alkoxylated derivatives can be used. For hardening by energy-rich radiation, a photoinitiating component can also be added. These comprise initiators known per se that can trigger radical polymerization after irradiation with energy-rich radiation, such as UV light. Such photoinitiators are described, for example, in P.K.T. Oldring (Ed.), Chemistry & Technology of UV & EB Formulations For Coatings, Inks & Paints, Vol. 3, 1991, SITA Technology, London, p. 61-325. They are used as an additive of the components indicated as a) and b) in amounts of 0.1 to 10 parts by weight, preferably 2 to 7 parts by weight, particularly preferably 3 to 4 parts by weight. The coating compositions according to the invention can be mixed with adjuvants and additives of various types. These include fillers, pigments, dyes, thixotropic agents, brighteners, matting agents or leveling agents, which are used in the usual amounts.

EXAMPLES Example 1 Preparation of the component a) First the dissolved gases were removed from the 1. 000 g (5.95 mol) of HDI in an agitator with internal thermometer, reflux condenser, gas inlet pipe and dosing device for the catalyst solution, at 60 ° C and a pressure of approx. 0.1 mbar in the course of one hour. Then dry nitrogen was blown in and while a weak stream of nitrogen was passed it was added in portions at an internal temperature of 60 ° C in the course of approx. 20 to 50 minutes a solution of tetrabutylphosphonium hydrogen difluoride (BuPT ~ x HF) in methanol / iso-propanol, containing 4.75% F ~, not total fluorine, (prepared "as described in the German patent application DE-A 19 824 485.2, Example la, there designated as stock solution 1) so that the temperature does not exceed 70 ° C.

After reaching the below-indicated value of the refractive index nD20 of the crude reaction mixture, the progress of the reaction was stopped by adding the corresponding molar amount of di-n-butyl phosphate for the consumption of the fluoride (see below) , stirring was continued for a further hour at 60 ° C and then the unreacted HDI was separated by molecular distillation in a short path evaporator at 0.15 mbar and at a heating medium temperature of 180 ° C. The data of the polyisocyanate components a) having HDI-iminooxadiazinedione groups thus obtained are shown below: Example Progress of the interrupted reaction to: nD20 1.4620, for this 421 mg of consumption of the catalyst solution indicated above, corresponding to 221 mg of di-n-butyl phosphate as finisher. Resin data: NCO content: 23.8%, rated according to DIN 53 185, dynamic viscosity at 23 ° C: 760 mPa.s (Newtonian fluid behavior), free HDI: 0.07% (by gas chromatography), Hazen color index: 21 Apha. He 45% by mole of the isocyanate groups of the HDI which reacted in the oligomerization reaction are in the form of iminooxadiazinedione groups, in addition to 52% by mole of isocyanate groups. The difference up to 100% in moles is essentially covered with uretdione groups (determined by 13 C NMR spectroscopy, as described in the document.

Le A 32 942 as well as in "Die Angewandte Makromolekulare Chemie 1986, 141, 173-183. "Example lb Progress of the interrupted reaction to: nD20 1.4670, for this 410 mg of consumption of the catalyst solution indicated above, corresponding to 215 mg of di-n-butyl phosphate as Finisher Resin data: NCO content: 23.2%, evaluated according to DIN 53 185, dynamic viscosity at 23 ° C: 1120 mPa.s (Newtonian fluid behavior), free HDI: 0.11% (by gas chromatography), Hazen color index: 23 Apha., iminooxadiazindiones: 43% by moles, isocyanurates: 56% by moles. Axis p or 2 305.3 g of the polyisocyanate of Example la) were dissolved in 122.7 g of butyl acetate. To this was added 0.1 g of dibutyltin dilaurate and 0.49 g of 2,6-di-tert-butyl-4-methyl-phenol. Passing air and stirring, the solution was heated to 60 ° C. The heat source was removed and 64.4 g of 2-hydroxypropyl acrylate were first added dropwise and then 134.0 g of hydroxyethyl acrylate so that the temperature does not exceed 60 ° C. The reaction is terminated when the NCO content of the solution is less than 0.10% by weight.

Example 3 615.4 g of the polyisocyanate of Example lb) were mixed with 0.5 g of dibutyltin dilaurate and 1.0 g of 2,6-di-tert-butyl-4-methyl-phenol. Passing air and stirring, the solution was heated to 60 ° C. The heat source was removed and 394.4 g of hydroxyethyl acrylate were added dropwise so that the temperature did not exceed 60 ° C. The reaction is terminated when the NCO content of the solution is less than 0.10% by weight. Subsequently, 0.5 g more than 2,6-di-tert-butyl-4-methyl-phenol was added as a stabilizer in the course of 10 min at 60 ° C. Example 4 Example 3 was repeated with the difference that 202.0 g of butyl acetate were furthermore disposed. E p p 5 435.0 g of the polyisocyanate of Example lb) were dissolved in 176.0 g of 1,6-hexanediol diacrylate. To this was added 0.35 g of dibutyltin dilaurate and 0.35 g of 2,6-di-tert-butyl-4-methyl-phenol. Passing air and stirring, the solution was heated to 60 ° C. The heat source was removed and 78.0 g of 2-hydroxypropyl acrylate, then 162 g of hydroxyethyl acrylate and finally 29.0 g of 2-ethyl-l, 3-hexanediol were first added dropwise so that the temperature does not exceed 60 ° C. The reaction is terminated when the NCO content of the solution is less than 0.10% by weight. Subsequently, 0.35 g more of 2,6-di-tert-butyl-4-methyl-phenol as stabilizer in the course of 10 min at 60 ° C. COMPARATIVE EXAMPLES: EXAMPLE COMPARISON 6 239.2 g of Desmodur * N 3600 (Bayer AG, Leverkusen, substantially polyisocyanate containing HDI-isocyanurate, NCO content: 23.4% by weight, viscosity 1200 mPa.sa 23 were dissolved. ° C) in 98.9 g of butyl acetate. To this was added 0.2 g of dibutyltin dilaurate and 0.4 g of 2,6-di-tert-butyl-4-methyl-phenol. Passing air and stirring, the solution was heated to 60 ° C. The heat source was removed and 50.7 g of 2-hydroxypropyl acrylate and then 105.6 g of hydroxyethyl acrylate were added dropwise first so that the temperature did not exceed 60 ° C. The reaction is terminated when the NCO content of the solution is less than 0.10% by weight. Comparative Example 7 248.4 g of Desmodur® VP LS 2025/1 (see Ex. 6) were dissolved in 102.3 g of butyl acetate and mixed with 0.2 g of dibutyltin dilaurate and 0.4 g of 2,6-di-tert-butyl-4-methyl-phenol. Passing air and stirring, the solution was heated to 6 ° C. The heat source was removed and 156.6 g of hydroxyethyl acrylate were added dropwise so that the temperature did not exceed 60 ° C. The reaction is terminated when the NCO content of the solution is less than 0.10% by weight. Then, an additional 0.1 g of 2,6-di-tert-butyl-4-methyl-phenol was added as a stabilizer in the course of 10 min at 60 ° C. Example of application 8 Properties of the products of Examples 2 to 5 according to the invention and of Comparative Examples 6 and 7: The viscosities of the products produced were determined with a rotary viascosimeter at 23 ° C. To check the tendency to crystallize the products were stored, part at 23 ° C, part at 8 ° C, and a possible thickening / crystallization was checked daily. The products that showed a thickening / crystallization were then thermally conditioned for 60 min at 60 ° C and then stirred briefly. The starting viscosity was recovered again as the newly produced measurement.

BuAc = n-butyl acetate, H DA = hexanediol acrylate The comparison of Examples 2 and 6 as well as of 4 and 7 shows that the products according to the invention have a substantially lower viscosity and storage stability. The products according to the invention obtained according to Examples 2 to 5 as well as the comparative products obtained according to Example 6 and 7 were mixed with 2.5% by weight respectively of Darocur * (photoinitiator, commercial product of Ciba Spezialtatenchemie GmbH) . After the application of the lacquer films on cardboard (application level 250 g / m2) they were moved through a high pressure mercury irradiator (Hanovia, 80 W / cm, distance 10 cm). At a band speed of at least 10 m / min, coatings resistant to solvents and scratches were formed. "Resistant to solvents" means in this case that the lacquer film still remained impeccable after at least 30 doubles passes with a cloth impregnated with n-butyl acetate under a load of 1 kg.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (4)

CLAIMS Having described the invention as above, the content of the following claims is claimed as property:

1. Coating agents that harden under the influence of energy-rich radiation characterized in that the coating agents contain a reaction product of: a) dimers of isocyanates (mixtures) based on aliphatic or cycloaliphatic diisocyanates constituted by 20 to 100 mol% of structural type compounds of iminooxadiazinedione of formula A, wherein R1, R2 and R3 represent, independently of one another (cyclo) optionally branched C-C20 alkyls, and X represents identical or different isocyanate or isocyanate-modified radicals of the structural type of iminooxadiazinedione, isocyanurate, uretdione, urethane, allophanate, biuret or oxadiazinetrione and carrying on N the aforementioned radicals R1, R2 and R3, with b) a component alcohol containing at least one monovalent, optionally branched, hydroxyalkyl Cx-C12 alkyl ester of (meth) acrylic acid.

2. Process for preparing urethanoacrylates according to claim 1 by reacting an isocyanate-containing component with a hydroxyl-containing component, containing at least one monovalent hydroxy-functional ester of (meth) acrylic acid in an NCO / equivalents ratio OH yield 0.7: 1 to 1: 1, characterized in that the isocyanate-containing component is of the type of component a).

3. Coating agents that harden under the influence of energy-rich radiation according to claim 1, characterized in that hexamethylene diisocyanate is used as aliphatic or cycloaliphatic diisocyanate.

4. Use of coating agents that harden under the influence of energy-rich radiation according to claim 1 as binders in lacquers and coatings that harden by UV light. SUMMARY OF THE INVENTION The present invention relates to novel urethanoacrylates, to the process for their preparation as well as to their use as a component of coating compositions that harden under the influence of energy-rich radiation.