Patent Application
20130195793
The present invention relates to radiation-curable antimicrobial coatings, to a process for preparation thereof, and to the use thereof.
WO 2008/131715 discloses silane-functional reaction products of diols with isocyanato-propyltriethoxysilane which lead in coating compositions to easy-clean coatings.
WO 2008/132045 describes compounds which carry at least one quaternary ammonium group and at least one (meth)acrylate group. Compounds of this kind are used in radiation-curable coating compositions and lead to biocidal coatings.
WO 2008/31596 describes coating compositions for producing radiation-curable medical coatings, in which hydrophilic polyfunctional (meth)acrylamides are used. In order to acquire antimicrobial properties, it is necessary to add compounds with antimicrobial activity to these coating compositions.
DE 19921904 discloses compounds for antimicrobial coating compositions that have silyl groups and (meth)acrylate groups.
DE 19700081 discloses radiation-curable, antimicrobial coating compositions comprising silylated (meth)acrylates, cinnamoylethyl (meth)acrylate, other radiation-curable monomers, such as (meth)acrylates, for example, and also ammonium compounds. A disadvantage is that the effect of the antimicrobial coating compositions is relatively weak and derives predominantly only from an antiadhesive effect rather than a biocidal effect.
It was an object of the present invention to provide radiation-curable coatings which can be equipped with a rapid and complete or near-complete antimicrobial activity and which at the same time produce coatings having good film properties.
This object has been achieved by antimicrobial, radiation-curable coatings obtained by reacting
The radiation-curable, antimicrobial coatings of the invention exhibit a strong and rapid antimicrobial activity which persists over a relatively long time, and at the same time the coatings obtained therewith exhibit good film properties, especially hardness.
The at least one urethane (meth)acrylate (A) comprises urethane (meth)acrylates of the kind comprising
The urethane (meth)acrylates (A) have preferably one to six, more preferably one to four, very preferably one to three, more particularly one to two, and especially just one (meth)acrylate group.
A (meth)acrylate group in the context of this specification is a methacrylate or acrylate group, preferably an acrylate group.
The urethane (meth)acrylates (A) have preferably one to four, more preferably one to three, very preferably one to two, and more particularly just one quaternary ammonium group.
“Quaternary ammonium groups” in the sense of the present specification are those which are substituted by three hydrocarbon radicals and are bonded by a spacer to the urethane (meth)acrylate. The number of carbon atoms in these quaternary ammonium groups is determined from the sum of the carbon atoms in the three hydrocarbon radicals and also of the carbon atoms in the spacer, account being taken here only of the carbon atoms between the nitrogen atom of the quaternary ammonium group and the first heteroatom.
The spacer comprises at least one carbon atom, preferably at least two carbon atoms.
Generally speaking, the spacer is not longer than ten carbon atoms, preferably not longer than six carbon atoms, and very preferably not longer than four carbon atoms.
Where the quaternary ammonium group comprises a ring, for example, the carbon atoms of the ring are of course included only once in the calculation.
According to this definition, a 2-(N,N,N-triethylammonium)ethyl group has eight carbon atoms and a 3-(N-ethylpiperidinium)propyl group has ten carbon atoms.
In one preferred embodiment, the quaternary ammonium group has the following formula (I)
R1R2R3N+—R4—
in which
R1, R2, and R3 each independently of one another are alkyl groups having 1 to 20, preferably one to 15 carbon atoms, aryl groups having 6 to 14, preferably 6 to 10, more preferably 6 carbon atoms, or aralkyl groups having 7 to 20, preferably 7 to 15, more preferably 7 to 10 carbon atoms, it also being possible for two of the radicals R1 to R3 together to be part of a ring, and
R4 is a divalent hydrocarbon radical having 1 to 10, preferably 2 to 6, more preferably 2 to 4 carbon atoms.
Examples of alkyl groups having 1 to 20 carbon atoms are methyl, ethyl, isopropyl, n-propyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-hexyl, n-heptyl, 2-ethylhexyl, n-octyl, n-decyl, 2-propylheptyl, n-dodecyl, isotridecyl, n-tetradecyl, n-hexadecyl, n-octadecyl, and n-eicosyl.
Examples of aryl groups having 6 to 14 carbon atoms are phenyl, α-naphthyl, and β-naphthyl.
Examples of aralkyl groups having 7 to 20 carbon atoms are benzyl, phenethyl, 3-phenylpropyl, 4-phenylbutyl, and 6-phenylhexyl.
Examples of divalent hydrocarbon radicals having 1 to 10 carbon atoms are 1,2-ethylene, 1,2-propylene, 1,3-propylene, 1,2-butylene, 1,3-butylene, 1,4-butylene, 1,6-hexylene, 2-methyl-1,3-propylene, 2-ethyl-1,3-propylene, 2,2-dimethyl-1,3-propylene, 1,8-octylene, and 1,10-decylene.
Preferably the radicals R1 to R3 independently of one another are each alkyl groups.
In one preferred embodiment of the present invention, the groups R1 to R4 in the quaternary ammonium groups of the formula (I) have in total at least 12 carbon atoms, preferably at least 14, more preferably at least 16, and very preferably at least 18 carbon atoms.
In another preferred embodiment at least one, preferably just one, of the radicals R1 to R3 has at least 10 and preferably at least 12 carbon atoms.
In another preferred embodiment, one of the radicals R1 to R3 has at least 10 and preferably at least 12 carbon atoms, and the two others each have not more than 4, preferably not more than 2, carbon atoms.
The compounds (A) are preferably urethane (meth)acrylates composed of
Isocyanate-reactive groups here are preferably hydroxyl, mercapto, or a primary or secondary amino groups, more preferably hydroxyl or primary amino groups, and very preferably hydroxyl groups.
The compounds (A) preferably have a (meth)acrylate group density of at least 0.5 mol per 1000 g, more preferably of 1 to 5, and very preferably of 2 to 4 mol per 1000 g.
The compounds (A) preferably have an ammonium group density of at least 0.07 mol per 1000 g, more preferably of 0.14 to 1, and very preferably of 0.14 to 0.5 mol per 1000 g.
The urethane (meth)acrylates (A) preferably have a number-average molar weight Mn of less than 5000, in particular below 2000, and particularly preferably below 1000 g/mol (determined by gel permeation chromatography using tetrahydrofuran and polystyrene as standard).
Components (a1)
Particularly suitable polyisocyanates as components (a1) for the polyurethanes of the invention are (cyclo)aliphatic diisocyanates and polyisocyanates based on (cyclo)aliphatic diisocyanates.
The term (cyclo)aliphatic is an abbreviation in this specification for cycloaliphatic or aliphatic.
Cycloaliphatic isocyanates are those which comprise at least one cycloaliphatic ring system.
Aliphatic isocyanates are those which comprise exclusively linear or branched chains, i.e., acyclic compounds.
The polyisocyanates which can be used in accordance with the invention do not have any aromatic groups.
The component (a1) is at least one di- or polyisocyanate, for example one to four, preferably one to three, more preferably one to two, and very preferably just one.
The monomeric isocyanates are preferably diisocyanates which carry just two isocyanate groups. It would also be possible in principle, however, for them to be monoisocyanates with one isocyanate group; such compounds, however, are less preferred.
Also suitable in principle are higher isocyanates containing on average more than 2 isocyanate groups; these, however, are less preferred. Suitability therefor is possessed, for example, by triisocyanates such as triisocyanatononane or 2′-isocyanatoethyl 2,6-diisocyanatohexanoate, or the mixtures of di-, tri- and higher polyisocyanates.
The monomeric isocyanates comprise substantially no reaction products of the isocyanate groups with themselves.
The monomeric isocyanates are preferably isocyanates having 4 to 20 C atoms. Examples of typical aliphatic diisocyanates are tetramethylene diisocyanate, 1,5-pentamethylene diisocyanate, hexamethylene diisocyanate (1,6-diisocyanatohexane), octamethylene diisocyanate, decamethylene diisocyanate, dodecamethylene diisocyanate, tetradecamethylene diisocyanate, derivatives of lysine diisocyanate, (e.g., methyl or ethyl 2,6-diisocyanato-hexanoate), trimethylhexane diisocyanate or tetramethylhexane diisocyanate. Examples of cycloaliphatic diisocyanates are 1,4-, 1,3- or 1,2-diisocyanatocyclohexane, 4,4′- or 2,4′-di(isocyanatocyclohexyl)methane, 1-isocyanato-3,3,5-trimethyl-5-(isocyanatomethyl)cyclo-hexane (isophorone diisocyanate), 1,3- or 1,4-bis(isocyanatomethyl)cyclohexane or 2,4-, or 2,6-diisocyanato-1-methylcyclohexane, and also 3 (or 4),8 (or 9)-bis(isocyanatomethyl)-tricyclo[5.2.1.02,6]decane isomer mixtures.
Particularly preferred diisocyanates are 1,6-hexamethylene diisocyanate, 1,3-bis(isocyanato-methyl)cyclohexane, and isophorone diisocyanate; very particular preference is given to isophorone diisocyanate and 1,6-hexamethylene diisocyanate, with more particular preference being given to isophorone diisocyanate.
It is also possible for mixtures of the stated isocyanates to be present.
Isophorone diisocyanate usually takes the form of a mixture, more particularly a mixture of the cis and trans isomers, generally in a ratio of around 60:40 to 80:20 (w/w), preferably in a ratio of around 70:30 to 75:25, more preferably in a ratio of around 75:25.
The amount of isomeric compounds in the diisocyanate is not critical to the process of the invention. Thus 1,6-hexamethylene diisocyanate may comprise, for example, a small fraction of 2-urethane (meth)acrylates and/or 3-methyl-1,5-pentamethylene diisocyanate.
For the present invention it is possible to use polyisocyanates not only based on those diisocyanates obtained by phosgenating the corresponding amines, but also those prepared without the use of phosgene, i.e., by phosgene-free processes. According to EP-A-0 126 299 (U.S. Pat. No. 4,596,678), EP-A-126 300 (U.S. Pat. No. 4,596,679), and EP-A-355 443 (U.S. Pat. No. 5,087,739), for example, (cyclo)aliphatic diisocyanates, such as 1,6-hexamethylene diisocyanate (HDI), can be prepared by reacting the (cyclo)aliphatic diamines with, for example, urea and alcohols to form (cyclo)aliphatic biscarbamic esters, and cleaving them thermally to give the corresponding diisocyanates and alcohols. The synthesis takes place, usually, continuously in a circulation process, and in the presence or absence of N-unsubstituted carbamic esters, dialkyl carbonates, and other byproducts recycled from the reaction process. Diisocyanates obtained in this way generally have a very low, or even unmeasurable, fraction of chlorinated compounds, which can lead to advantageous color numbers in the products. It is a further advantage of the present invention that the process of the invention is based on aliphatic diisocyanates and is independent of their preparation, i.e., independent of whether the preparation is via a phosgenation or via a phosgene-free process.
In one embodiment of the present invention the diisocyanate has a total hydrolyzable chlorine content of less than 200 ppm, preferably of less than 120 ppm, more preferably less than 80 ppm, very preferably less than 50 ppm, more particularly less than 15 ppm, and especially less than 10 ppm. This may be measured, for example, by the ASTM specification D4663-98. It is also, however, possible of course to use diisocyanates having a higher chlorine content, of up to 500 ppm, for example.
It will be appreciated that it is also possible to use mixtures of diisocyanate obtained by reacting the corresponding diamine with, for example, urea and alcohols, and cleaving the resultant biscarbamic esters, with diisocyanate obtained by phosgenating the corresponding amine.
The polyisocyanates based on these diisocyanates are preferably the following compounds:
In preferred compounds (a1) the polyisocyanate comprises at least one moiety selected from the group consisting of isocyanurates, biurets, and allophanates, preferably from the group consisting of isocyanurates and allophanates, as described in WO 00/39183, which is hereby considered by reference to be part of the present disclosure; with particular preference the compound in question is a polyisocyanate containing isocyanurate groups.
In one particularly preferred embodiment the polyisocyanate (a1) is a polyisocyanate based on 1,6-hexamethylene diisocyanate and/or isophorone diisocyanate, very preferably based on isophorone diisocyanate.
More particularly the compound (a1) is a polyisocyanate which comprises isocyanurate groups and is based on isophorone diisocyanate.
Components (a2)
Components (a2) each comprise, at least one, one to three, for example, preferably one to two, and very preferably just one compound having at least one, preferably just one, group that is reactive toward isocyanate groups, and at least one (meth)acrylate group.
Preferred compounds of components (a2) are, for example, the esters of dihydric or polyhydric alcohols with acrylic acid or methacrylic acid, more preferably acrylic acid.
Suitable alcohols are, for example, diols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,1-dimethylethane-1,2-diol, 2-butyl-2-ethyl-1,3-propanediol, 2-ethyl-1,3-propanediol, 2-methyl-1,3-propanediol, neopentylglycol, neopentylglycol hydroxypivalate, 1,2-, 1,3- or 1,4-butanediol, 1,6-hexanediol, 1,10-decanediol, bis-(4-hydroxycyclohexane)-isopropylidene, tetramethylcyclobutanediol, 1,2-, 1,3- or 1,4-cyclohexanediol, cyclooctanediol, norbornanediol, pinanediol, decalindiol, 2-ethyl-1,3-hexanediol, 2,4-diethyloctane-1,3-diol, hydroquinone, bisphenol A, bisphenol F, bisphenol B, bisphenol S, 2,2-bis(4-hydroxy-cyclohexyl)propane, 1,1-, 1,2-, 1,3-, and 1,4-cyclohexanedimethanol, 1,2-, 1,3- or 1,4-cyclo-hexanediol, and tricyclodecanedimethanol.
Suitable triols and polyols have, for example, 3 to 25, preferably 3 to 18, carbon atoms. They include, for example trimethylolbutane, trimethylolpropane, trimethylolethane, pentaerythritol, glycerol, ditrimethylolpropane, dipentaerythritol, ditrimethylolpropane, sorbitol, mannitol, diglycerol, threitol, erythritol, adonitol (ribitol), arabitol (lyxitol), xylitol, dulcitol (galactitol), maltitol or isomalt.
Preferably the compounds of components (a2) are selected from 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 3-hydroxybutyl acrylate, 3-hydroxybutyl methacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, 6-hydroxyhexyl acrylate, 6-hydroxyhexyl methacrylate, 3-hydroxy-2-ethylhexyl acrylate, 3-hydroxy-2-ethylhexyl methacrylate, trimethylolpropane mono- or -diacrylate, pentaerythritol diacrylate or triacrylate, dipentaerythritol pentaacrylate, and mixtures thereof.
Preferred in particular as compounds (a2) are 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, pentaerythritol triacrylate, and dipentaerythritol pentaacrylate.
Components a3)
The optional components a3) comprise at least one compound having at least two, for example two to six, preferably two to four, more preferably two to three, and very preferably just two groups that are reactive toward isocyanate groups, selected from hydroxyl, mercapto, primary and/or secondary amino groups, preferably hydroxyl and primary amino groups, more preferably hydroxyl groups.
Low molecular weight alcohols a3) have a molecular weight of not more than 500 g/mol. Particularly preferred are alcohols having 2 to 20 carbon atoms and, for example, 2 to 6 hydroxyl groups, preferably 2 to 4, more preferably 2 to 3, and very preferably just 2 hydroxyl groups. Preference is given in particular to hydrolysis-stable short-chain diols having 4 to 20, preferably 6 to 12, carbon atoms. These include preferably 1,1-, 1,2-, 1,3- or 1,4-di(hydroxy-methyl)cyclohexane, 2,2-bis(4′-hydroxycyclohexyl)propane, 1,2-, 1,3- or 1,4-cyclohexanediol, tetramethylcyclobutanediol, cyclooctanediol or norbornanediol. Particular preference is given to using aliphatic hydrocarbon-diols, such as the isomeric butanediols, pentanediols, hexanediols, heptanediols, octanediols, nonanediols, decanediols, undecanediols and dodecanediols. Particular preference is given to 1,2-, 1,3- or 1,4-butanediol, 1,4-pentanediol, 1,5-pentanediol, 1,6-hexanediol, 2,5-hexanediol, di(hydroxymethyl)cyclohexane isomers and 2,2-bis(4′-hydroxy-cyclohexyl)propane. With very particular preference the diols (a3) are cycloaliphatic diols, more particularly 1,1-, 1,2-, 1,3- or 1,4-di(hydroxymethyl)cyclohexane, 2,2-bis(4′-hydroxycyclohexyl)-propane, 1,2-, 1,3- or 1,4-cyclohexanediol.
Components a4)
Suitable compounds a4) are also polymeric polyols. The number-average molecular weight Mn of these polymers is preferably in a range from more than 500 to 100 000, more preferably 500 to 10 000. The OH numbers are situated preferably in a range from about 20 to 300 mg KOH/g polymer.
The functionality of the polyols a4) is at least two, two to six for example, preferably two to four, more preferably two to three, and very preferably just two.
Preferred compounds a4) are polyesterols, polyetherols, and polycarbonate polyols, more preferably polyesterols and polyetherols, and very preferably polyesterols.
Preferred polyesterols are those based on aliphatic, cycloaliphatic and/or aromatic dicarboxylic, tricarboxylic and polycarboxylic acids with diols, triols and/or polyols, and also lactone-based polyesterols.
Polyesterpolyols, are known, for example, from Ullmanns Encyklopädie der technischen Chemie, 4th edition, volume 19, pp. 62 to 65. Preference is given to using polyesterpolyols obtained by reaction of dihydric alcohols with dibasic carboxylic acids. Instead of the free polycarboxylic acids it is also possible to use the corresponding polycarboxylic anhydrides or corresponding polycarboxylic esters of lower alcohols or mixtures thereof to prepare the polyesterpolyols. The polycarboxylic acids may be aliphatic, cycloaliphatic, araliphatic, aromatic or heterocyclic, and if desired may be substituted, by halogen atoms, for example, and/or unsaturated. Examples thereof that may be mentioned include the following:
oxalic acid, maleic acid, fumaric acid, succinic acid, glutaric acid, adipic acid, sebacic acid, dodecanedioic acid, o-phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, azelaic acid, 1,4-cyclohexanedicarboxylic acid or tetrahydrophthalic acid, suberic acid, azelaic acid, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, tetrachloro-phthalic anhydride, endomethylenetetrahydrophthalic anhydride, glutaric anhydride, maleic anhydride, dimeric fatty acids, their isomers and hydrogenation products, and their esterifiable derivatives, such as anhydrides or dialkyl esters, for example, C1-C4 alkyl esters, preferably methyl, ethyl or n-butyl esters, of the stated acids are employed. Dicarboxylic acids of general formula HOOC—(CH2)y—COOH are preferred, where y is a number from 1 to 20, preferably an even number from 2 to 20; particular preference is given to succinic acid, adipic acid, sebacic acid, and dodecanedicarboxylic acid.
Suitable polyhydric alcohols for preparing the polyesterols include 1,2-propanediol, ethylene glycol, 2,2-dimethyl-1,2-ethanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butane-diol, 3-methylpentane-1,5-diol, 2-ethylhexane-1,3-diol, 2,4-diethyloctane-1,3-diol, 1,6-hexane-diol, poly-THF with a molar mass between 162 and 2000, poly-1,3-propanediol with a molar mass between 134 and 2000, poly-1,2-propanediol with a molar mass between 134 and 2000, polyethylene glycol with a molar mass between 106 and 2000, neopentylglycol, neopentylglycol hydroxypivalate, 2-ethyl-1,3-propanediol, 2-methyl-1,3-propanediol, 2,2-bis(4-hydroxycyclo-hexyl)propane, 1,1-, 1,2-, 1,3-, and 1,4-cyclohexanedimethanol, 1,2-, 1,3- or 1,4-cyclohexane-diol, trimethylolbutane, trimethylolpropane, trimethylolethane, neopentylglycol, pentaerythritol, glycerol, ditrimethylolpropane, dipentaerythritol, sorbitol, mannitol, diglycerol, threitol, erythritol, adonitol (ribitol), arabitol (lyxitol), xylitol, dulcitol (galactitol), maltitol or isomalt, which if desired may be alkoxylated as described above.
Preference is given to alcohols of the general formula HO—(CH2)x—OH, where x is a number from 1 to 20, preferably an even number from 2 to 20. Preferred are ethylene glycol, butane-1,4-diol, hexane-1,6-diol, octane-1,8-diol, and dodecane-1,12-diol. Additionally preferred is neopentylglycol.
Also suitable, furthermore, are polycarbonate-diols, of the kind obtainable, for example, by reacting phosgene with an excess of the low molecular weight alcohols stated as synthesis components for the polyesterpolyols.
Lactone-based polyesterdiols are also suitable, these being homopolymers or copolymers of lactones, preferably hydroxyl-terminated adducts of lactones with suitable difunctional starter molecules. Suitable lactones are preferably those deriving from compounds of the general formula HO—(CH2)z—COOH, where z is a number from 1 to 20, and where one H atom of a methylene unit may also have been substituted by a C1 to C4 alkyl radical. Examples are ε-caprolactone, β-propiolactone, gamma-butyrolactone and/or methyl-ε-caprolactone, 4-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid or pivalolactone, and mixtures thereof. Examples of suitable starter components are the low molecular mass dihydric alcohols specified above as a synthesis component for the polyesterpolyols. The corresponding polymers of ε-caprolactone are particularly preferred. Lower polyesterdiols or polyetherdiols may also be used as starters for preparing the lactone polymers. Instead of the polymers of lactones it is also possible to use the corresponding, chemically equivalent polycondensates of the hydroxycarboxylic acids corresponding to the lactones.
In the case of the lactone-based polyesterol, preference is given to a polycaprolactone diol, which, formally, is an adduct of caprolactone with a diol HO—R—OH, having the formula
HO—[—CH2—CH2—CH2—CH2—CH2—(CO)—O]n—R—OH
or
HO—[—CH2—CH2—CH2—CH2—CH2—(CO)—O]n1—R—[—O—(CO)—CH2—CH2—CH2—CH2—CH2—]n2—OH,
in which
Aliphatic radicals R are, for example, linear or branched alkylene, e.g., methylene, 1,2-ethylene, 1,2- or 1,3-propylene, 1,2-, 1,3- or 1,4-butylene, 1,1-dimethyl-1,2-ethylene or 1,2-dimethyl-1,2-ethylene, 1,5-pentylene, 1,6-hexylene, 1,8-octylene, 1,10-decylene, or 1,12-dodecylene. Preference is given to 1,2-ethylene, 1,2- or 1,3-propylene, 1,4-butylene and 1,5-pentylene, particular preference to 1,4-butylene and 1,6-hexylene.
Conceivable, albeit less preferably, are cycloaliphatic radicals, examples being cyclopropylene, cyclopentylene, cyclohexylene, cyclooctylene, and cyclododecylene.
Preferred polyesterols as compounds (a4) have a functionality in terms of free hydroxyl groups of at least 2, more preferably of 2 to 6, very preferably of 2 to 4, more particularly of 2 to 3, and especially of 2 exactly.
The molecular weights Mn of the polyesterols lie preferably between 500 and 4000 (Mn determined by gel permeation chromatography with polystyrene as standard and tetrahydrofuran as eluent).
Components (a5)
The at least one, one to four for example, preferably one to three, more preferably one to two, and preferably just one compound (a5) has at least one, one to three for example, and preferably one to two groups that are reactive toward isocyanate groups, and at least one, one to four for example, preferably one to three, more preferably one to two, and very preferably just one quaternary ammonium group.
Particularly preferred compounds (a5) are those of the formula (II)
R1R2R3N+—R4—Y
in which
R1 to R4 have the definitions stated above and
Y represents an isocyanate-reactive group, preferably an —OH or —NH2 group.
Preferred compounds (a5) having an isocyanate-reactive group are 2-[N,N-bis(tridecyl)-N-methylammonium)]ethanol, 2-[N,N-bis(hexyl)-N-methylammonium)]ethanol, 2-[N,N-bis(tridecyl)-N-methylammonium)]propan-1-ol, 2-[N,N-bis(hexyl)-N-methylammonium)]-propan-1-ol, N-alkylated N,N-dimethylethanolamines, and N-alkylated N,N-dimethylpropanol-amines, in which the alkyl radical preferably comprises at least 6, more preferably at least 8, and very preferably at least 12 carbon atoms. Preference extends to the products of such compounds that are further reacted one to fifty times, preferably two to thirty times, and more preferably four to twenty times with ethylene oxide and/or propylene oxide, preferably only with ethylene oxide.
Preferred compounds (a5) having two isocyanate-reactive groups are bis(2-hydroxyethyl)alkyl-methylammonium salts, bis(2-hydroxypropyl)alkylmethylammonium salts, bis(2-hydroxyethyl)-alkylbenzylammonium salts, and bis(2-hydroxypropyl)alkylbenzylammonium salts, in which the alkyl radical comprises preferably at least 6, more preferably at least 8, and very preferably at least 12 carbon atoms. Preference extends to the products of such compounds that are further reacted one to fifty times, preferably two to thirty times, and more preferably four to twenty times with ethylene oxide and/or propylene oxide, preferably only with ethylene oxide.
Possible counterions of the ammonium salts are halides, as for example chloride, bromide or iodide, sulfate, hydrogensulfate, methylsulfate, ethylsulfate, sulfonate, hydrogensulfonate, methylsulfonate, tosylate, mesylate, phosphate, hydrogenphosphate, dihydrogenphosphate, carbonate, hydrogencarbonate, methylcarbonate, ethylcarbonate, and butylcarbonate.
One possible embodiment involves attaching the ammonium compound to the polyurethane of the invention not via a compound of the formula (II) but instead via a compound (a5a) which has at least one, one to three for example, preferably one to two, and very preferably just one group that is reactive toward isocyanate groups, and a first reactive group, with the attachment of the ammonium group taking place by further reaction with a compound (a5b) which has a further reactive group, complementary to the first reactive group, and at least one, one to four for example, preferably one to three, more preferably one to two, and very preferably just one quaternary ammonium group.
Examples of such first reactive groups and further reactive groups complementary thereto are as follows:
Among these combinations it is preferred if both the compound (a5a) and the compound (a5b) carry identical or different alkoxysilyl groups.
It is generally sufficient here if one silyl group is substituted by at least one alkoxy radical, one to three for example, preferably two or three, and very preferably by three.
The groups in question are preferably tris(alkyloxy)silyl groups or alkylbis(alkyloxy)silyl groups, more preferably tris(C1-C4-alkyloxy)silylgroups or C1-C4-alkylbis(C1-C4-alkyloxy)silyl groups.
More preferably the groups in question are diethoxymethylsilyl, dimethoxymethylsilyl, methoxydimethylsilyl, ethoxydimethylsilyl, phenoxydimethylsilyl, triethoxysilyl or trimethoxysilyl groups.
With very particular preference the compound (a5a) conforms to the formula (III)
(R5O)3Si—R6—Y,
in which
Y has the above definition,
R5 is C1-C6 alkyl, preferably C1-C4 alkyl, more preferably methyl, ethyl, n-propyl, tert-butyl, and n-butyl, very preferably methyl, ethyl, and n-butyl, and more particularly methyl, and
R6 is a divalent hydrocarbon radical having 1 to 10, preferably 2 to 6, more preferably 2 to 4 carbon atoms.
Preferred compounds (a5a) are 3-aminopropylsiloxanes and 2-aminoethylsiloxanes, with 3-aminopropyltriethoxysilane being particularly preferred.
Reaction in that case takes place preferably with compounds (a5b) of the formula (IV)
R1R2R3N+—R4—Si(OR7)3
in which
R1 to R4 have the above definitions and
R7 is C1-C6 alkyl, preferably C1-C4 alkyl, more preferably methyl, ethyl, n-propyl, tert-butyl, and n-butyl, very preferably methyl, ethyl, and n-butyl, and more particularly methyl.
Preferred compounds (a5b) are 3-ammoniumpropylsiloxanes and 2-ammoniumethylsiloxanes, with the ammonium groups being in each case as defined above.
It is possible to prepare the urethane (meth)acrylates of the invention in such a way that first of all the compound (a5a) is installed and the resulting compound is only then reacted with the compound (a5b); alternatively, preparation may take place by simultaneous installation of the compounds (a5a) and (a5b) into the urethane (meth)acrylates. The latter, however, is less preferred.
The construction of the urethane (meth)acrylate of the invention with compounds (a5) is, however, preferred over the construction with the compounds (a5a) and (a5b).
Components (a6)
In the urethane (meth)acrylates of the invention it is possible as optional components (a6) to use at least one further compound having just one group that is reactive toward isocyanate groups. This group may be a hydroxyl, mercapto or a primary or secondary amino group. Suitable compounds (a6) are the customary compounds known to the skilled person, which are used typically in polyurethane production as “stoppers” for lowering the number of reactive free isocyanate groups and/or for modifying the polyurethane properties. They include, for example, monofunctional alcohols, such as methanol, ethanol, n-propanol, isopropanol, n-butanol, etc. Suitable components (a6) are also amines having a primary or secondary amino group, such as methylamine, ethylamine, n-propylamine, diisopropylamine, dimethylamine, diethylamine, di-n-propylamine, diisopropylamine, etc.
The urethane (meth)acrylates (A) of the invention generally have the following composition per 100 mol % of reactive isocyanate groups in (a1) (in total):
For the preparation of the polyurethanes of the invention, the starting components (a1) to (a6) where used, are reacted with one another at temperatures of 40 to 180° C., preferably 50 to 150° C., while observing the NCO/OH equivalents ratio indicated above.
The reaction generally takes place until the desired NCO number in accordance with DIN 53185 has been reached.
The reaction time is generally 10 minutes to 12 hours, preferably 15 minutes to 10 hours, more preferably 20 minutes to 8 hours, and very preferably 1 to 8 hours.
To accelerate the reaction it is possible optionally to use suitable catalysts.
The formation of the adduct from isocyanate-group-containing compound and the compound which comprises groups reactive toward isocyanate groups is generally accomplished by mixing the components in any order, optionally at elevated temperature.
It is preferred here to add the compound that comprises groups reactive toward isocyanate groups to the isocyanate-group-containing compound, more preferably in a plurality of steps.
With particular preference, the isocyanate-group-containing compound is introduced and the compounds comprising isocyanate-reactive groups are added. More particularly, first of all, the isocyanate-group-containing compound (a1) is added, and then (a2) and subsequently (a5) are added, or, preferably, first of all the isocyanate-group-containing compound (a1) is introduced, then (a5) and subsequently (a2) are added. After that it is possible optionally to add further components desired.
It is of course also possible to add (a2) and (a5) in a mixture with one another.
The mixture of the urethane (meth)acrylate (A) according to the invention comprises at least one hydrophilic reactive diluent (B) and also, optionally, at least one further reactive diluent (C), which is different from (B).
Compounds (B) and (C) are compounds of the kind typically used as reactive diluents. These include, for example, the reactive diluents as described in P. K. T. Oldring (editor), Chemistry & Technology of UV & EB Formulations for Coatings, Inks & Paints, Vol. II, Chapter III: Reactive Diluents for UV & EB Curable Formulations, Wiley and SITA Technology, London 1997.
Examples of reactive diluents include esters of (meth)acrylic acid with alcohols which have 1 to 20 C atoms, e.g., methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl acrylate, dihydrodicyclopentadienyl acrylate.
Compounds having at least two free-radically polymerizable C═C double bonds: these include, in particular, the diesters and polyesters of the aforementioned α,β-ethylenically unsaturated monocarboxylic and/or dicarboxylic acids with diols or polyols. Particularly preferred are hexanediol diacrylate, hexanediol dimethacrylate, octanediol diacrylate, octanediol dimethacrylate, nonanediol diacrylate, nonanediol dimethacrylate, decanediol diacrylate, decanediol dimethacrylate, pentaerythritol diacrylate, dipentaerythritol tetraacrylate, dipenta-erythritol triacrylate, pentaerythritol tetraacrylate, etc. Also preferred are the esters of alkoxylated polyols with α,β-ethylenically unsaturated monocarboxylic and/or dicarboxylic acids, such as, for example, the polyacrylates or polymethacrylates of alkoxylated trimethylolpropane, glycerol or pentaerythritol. Additionally suitable are the esters of alicyclic diols, such as cyclohexanediol di(meth)acrylate and bis(hydroxymethylethyl)cyclohexane di(meth)acrylate. Further suitable reactive diluents are trimethylolpropane monoformal acrylate, glycerol formal acrylate, 4-tetrahydropyranyl acrylate, 2-tetrahydropyranyl methacrylate, and tetrahydrofurfuryl acrylate.
Further suitable reactive diluents are, for example, polyether (meth)acrylates.
Polyether (meth)acrylates are preferably (meth)acrylates of singly to vigintuply and more preferably triply to decuply ethoxylated, propoxylated or mixedly ethoxylated and propoxylated, and more particularly exclusively ethoxylated, neopentylglycol, trimethylolpropane, trimethylolethane or pentaerythritol.
It is possible, furthermore, to use singly to vigintuply and more preferably triply to decuply ethoxylated, propoxylated or mixedly ethoxylated and propoxylated, and more particularly exclusively ethoxylated, glycerol.
Preferred polyfunctional, polymerizable compounds are ethylene glycol diacrylate, 1,2-propane-diol diacrylate, 1,3-propanediol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, pentaerythritol tetraacrylate, polyesterpolyol acrylates, polyetherol acrylates, and triacrylate of singly to vigintuply alkoxylated, more preferably ethoxylated, trimethylolpropane.
Polyether (meth)acrylates may also be (meth)acrylates of polyTHF having a molar weight between 162 and 2000, poly-1,3-propanediol having a molar weight between 134 and 2000 or polyethylene glycol having a molar weight between 238 and 2000.
The compound (B) which is present in accordance with the invention is a hydrophilic reactive diluent, the term “hydrophilic” in the context of this specification being understood to mean that it has a calculated log P value of not more than 1.0, the calculation of the log P values taking place with the program ACD/PhysChem Suite, Version 12.01 from Advanced Chemistry Development, Inc. (ACD/Labs, Ontario, Canada). The structures of the compounds for calculation are input in two-dimensional form in this case.
Preferred hydrophilic reactive diluents (B) acquire their hydrophilic quality from functional groups other than acid groups.
Acid groups in this context are free carboxyl groups (—COOH), sulfonic acid groups (—SO3H), sulfinic acid groups (—SO2H), phosphonic acid groups (—PO(OH)2), phosphinic acid groups (>PO(OH)), and also partially esterified sulfuric acids and phosphoric acids which carry (—OSO3H) or (—OPO(OH)2) groups.
Preferably excluded as reactive diluents, therefore, are α,β-unsaturated carboxylic acids, sulfonic acids, and phosphonic acids, more particularly methacrylic acid, ethacrylic acid, maleic acid including its anhydride, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, vinylacetic acid, allylacetic acid, crotonic acid, vinylsulfonic acid, and vinylphosphonic acid.
The compounds (B) are preferably selected from the group consisting of hydroxyalkyl (meth)acrylates and N-vinyl lactams, and more preferably are hydroxyalkyl (meth)acrylates
Hydroxyalkyl (meth)acrylates as compounds (B) are preferably w-hydroxyalkyl (meth)acrylates or (ω-1)-hydroxyalkyl (meth)acrylates, preferably w-hydroxyalkyl (meth)acrylates.
Particularly preferred hydroxyalkyl (meth)acrylates (B) are those of the formula
H2C═C(R9)COO—R8—OH,
in which
R9 is hydrogen or methyl, preferably hydrogen, and
R8 is a divalent hydrocarbon radical having 2 to 10, preferably 2 to 6, more preferably 2 to 4 carbon atoms.
Preferred radicals R8 are, for example, linear or branched alkylene, e.g., 1,2-ethylene, 1,2- or 1,3-propylene, 1,2-, 1,3- or 1,4-butylene, 1,1-dimethyl-1,2-ethylene or 1,2-dimethyl-1,2-ethylene, 1,5-pentylene, 1,6-hexylene, 1,8-octylene, 1,10-decylene, or 1,12-dodecylene. Preference is given to 1,2-ethylene, 1,2- or 1,3-propylene, 1,4-butylene, and 1,6-hexylene, particular preference to 1,2-ethylene, 1,2- or 1,3-propylene, very particular preference to 1,2-ethylene and 1,2-propylene, and, more particularly, 1,2-ethylene.
The compound (B) is preferably 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 3-hydroxy-propyl acrylate, 2-hydroxypropyl methacrylate, 2-hydroxyethyl methacrylate or 4-hydroxybutyl acrylate, more preferably 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, or 2-hydroxyethyl methacrylate, and very preferably 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate or 2-hydroxyethyl methacrylate.
N-Vinyl lactams as compounds (B) are preferably N-vinylated lactams having five- to twelve-membered ring systems, preferably five- to ten-membered and more preferably five- to seven-membered ring systems.
Preferred N-vinyl lactams are those of the formula
in which
R10 is a divalent hydrocarbon radical having 2 to 10, preferably 2 to 6, more preferably 3 to 5 carbon atoms.
Preferred radicals R11 are, for example, linear or branched alkylene, e.g. 1,2-ethylene, 1,2- or 1,3-propylene, 1,2-, 1,3- or 1,4-butylene, 1,1-dimethyl-1,2-ethylene or 1,2-dimethyl-1,2-ethylene, 1,5-pentylene, 1,6-hexylene, 1,8-octylene or 1,10-decylene. Preference is given to 1,3-propylene, 1,4-butylene, 1,5-pentylene, 1,5-hexylene, and 1,6-hexylene, particular preference to 1,3-propylene, 1,4-butylene, and 1,5-pentylene, very particular preference to 1,3-propylene and 1,5-pentylene.
Preferred N-vinyl lactams as compounds (B) are N-vinylpyrrolidone or N-vinylcaprolactam.
Compound (B) may be a single compound or a mixture of two or more, up to four for example, preferably up to three compounds, more preferably one or two compounds, and very preferably just one compound.
Optionally there may be at least one reactive diluent (C) present, which is not a hydrophilic reactive diluent, i.e., is different from the reactive diluent (B), and preferably has a log P of more than 1.
Particularly preferred compounds (C) are polyfunctional (meth)acrylates, in other words having a functionality of at least 2, 2 to 10 for example, preferably 2 to 6, more preferably 2 to 5, and very preferably 2 to 4.
Compounds (C) of the kind used typically as reactive diluents are known per se to the skilled person. They include, for example, the reactive diluents as described in P. K. T. Oldring (editor), Chemistry & Technology of UV & EB Formulations for Coatings, Inks & Paints, Vol. II, Chapter III: Reactive Diluents for UV & EB Curable Formulations, Wiley and SITA Technology, London 1997.
Compounds having at least two free-radically polymerizable C═C double bonds: these include, in particular, the diesters and polyesters of (meth)acrylic acid with diols or polyols. Particularly preferred are 1,4-butanediol di(meth)acrylate, 1,6-hexanediol diacrylate, hexanediol dimethacrylate, octanediol diacrylate, octanediol dimethacrylate, nonanediol diacrylate, nonanediol dimethacrylate, decanediol diacrylate, decanediol dimethacrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, pentaerythritol diacrylate, dipentaerythritol tetraacrylate, dipentaerythritol triacrylate, pentaerythritol tetraacrylate, etc.
Also preferred are the esters of alkoxylated polyols with (meth)acrylic acid, such as the polyacrylates or polymethacrylates of, on average per OH group, singly to decuply, preferably singly to pentuply, more preferably singly to triply, and very preferably singly to doubly alkoxylated, for example ethoxylated and/or propoxylated, preferably ethoxylated or propoxylated, and more preferably exclusively ethoxylated, trimethylolpropane, glycerol or pentaerythritol.
Additionally suitable are the esters of alicyclic diols, such as cyclohexanediol di(meth)acrylate and bis(hydroxymethylethyl)cyclohexane di(meth)acrylate.
Further suitable reactive diluents are for example urethane (meth)acrylates, epoxy (meth)acrylates, polyether (meth)acrylates, polyester (meth)acrylates or polycarbonate (meth)acrylates.
Urethane (meth)acrylates are obtainable for example by reacting polyisocyanates with hydroxyalkyl (meth)acrylates or hydroxyalkyl vinyl ethers and, optionally, chain extenders such as diols, polyols, diamines, polyamines, or dithiols or polythiols.
Urethane (meth)acrylates of this kind comprise as synthesis components substantially:
The urethane (meth)acrylates preferably have a number-average molar weight Mn of 500 to 20 000, in particular of 500 to 10 000 and more preferably 600 to 3000 g/mol (determined by gel permeation chromatography using tetrahydrofuran and polystyrene as standard).
The urethane (meth)acrylates preferably have a (meth)acrylic group content of 1 to 5, more preferably of 2 to 4, mol per 1000 g of urethane (meth)acrylate.
Particularly preferred urethane (meth)acrylates have an average functionality of 1.5 to 4.5.
Epoxy (meth)acrylates are preferably obtainable by reacting epoxides with (meth)acrylic acid. Examples of suitable epoxides include epoxidized olefins, aromatic glycidyl ethers or aliphatic glycidyl ethers, preferably those of aromatic or aliphatic glycidyl ethers.
Examples of possible epoxidized olefins include ethylene oxide, propylene oxide, isobutylene oxide, 1-butene oxide, 2-butene oxide, vinyloxirane, styrene oxide or epichlorohydrin, preference being given to ethylene oxide, propylene oxide, isobutylene oxide, vinyloxirane, styrene oxide or epichlorohydrin, particular preference to ethylene oxide, propylene oxide or epichlorohydrin, and very particular preference to ethylene oxide and epichlorohydrin.
Aromatic glycidyl ethers are, for example, bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol B diglycidyl ether, bisphenol S diglycidyl ether, hydroquinone diglycidyl ether, alkylation products of phenol/dicyclopentadiene, e.g., 2,5-bis[(2,3-epoxypropoxy)phenyl]octa-hydro-4,7-methano-5H-indene (CAS No. [13446-85-0]), tris[4-(2,3-epoxypropoxy)phenyl]-methane isomers (CAS No. [66072-39-7]), phenol-based epoxy novolaks (CAS No. [9003-35-4]), and cresol-based epoxy novolaks (CAS No. [37382-79-9]).
Preference is given to bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol B diglycidyl ether, and bisphenol S diglycidyl ether, and bisphenol A diglycidyl ether is particularly preferred.
Examples of aliphatic glycidyl ethers include 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, 1,1,2,2-tetrakis[4-(2,3-epoxypropoxy)phenyl]ethane (CAS No. [27043-37-4]), diglycidyl ether of polypropylene glycol (α,ω-bis(2,3-epoxypropoxy)poly(oxypropylene) (CAS No. [16096-30-3]) and of hydrogenated bisphenol A (2,2-bis[4-(2,3-epoxypropoxy)cyclohexyl]propane, CAS No. [13410-58-7]).
Preference is given to 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, and 2,2-bis[4-(2,3-epoxy-propoxy)cyclohexyl]propane.
The abovementioned aromatic glycidyl ethers are particularly preferred.
The epoxy (meth)acrylates and epoxy vinyl ethers preferably have a number-average molar weight Mn of 200 to 20 000, more preferably of 200 to 10 000 g/mol, and very preferably of 250 to 3000 g/mol; the amount of (meth)acrylic or vinyl ether groups is preferably 1 to 5, more preferably 2 to 4, per 1000 g of epoxy (meth)acrylate or vinyl ether epoxide (determined by gel permeation chromatography using polystyrene as standard and tetrahydrofuran as eluent).
Preferred epoxy (meth)acrylates have an OH number of 40 to 400 mg KOH/g.
Preferred epoxy (meth)acrylates have an average OH functionality of 1.5 to 4.5.
Particularly preferred epoxy (meth)acrylates are those such as are obtained from processes in accordance with EP-A-54 105, DE-A 33 16 593, EP-A 680 985, and EP-A-279 303, in which in a first stage a (meth)acrylic ester is prepared from (meth)acrylic acid and hydroxy compounds and in a second stage excess (meth)acrylic acid is reacted with epoxides.
Suitable polyester (meth)acrylates are at least partly or, preferably, completely (meth)acrylated reaction products of polyesterols of the kind listed above under compounds a4).
Carbonate (meth)acrylates
Carbonate (meth)acrylates comprise on average preferably 1 to 5, especially 2 to 4, more preferably 2 to 3 (meth)acrylic groups, and very preferably 2 (meth)acrylic groups.
The number-average molecular weight Mn of the carbonate (meth)acrylates is preferably less than 3000 g/mol, more preferably less than 1500 g/mol, very preferably less than 800 g/mol (determined by gel permeation chromatography using polystyrene as standard, tetrahydrofuran as solvent).
The carbonate (meth)acrylates are obtainable in a simple manner by transesterifying carbonic esters with polyhydric, preferably dihydric, alcohols (diols, hexanediol for example) and subsequently esterifying the free OH groups with (meth)acrylic acid, or else by trans-esterification with (meth)acrylic esters, as described for example in EP-A 92 269. They are also obtainable by reacting phosgene, urea derivatives with polyhydric, e.g., dihydric, alcohols.
Also conceivable are (meth)acrylates or vinyl ethers of polycarbonate polyols, such as the reaction product of one of the aforementioned diols or polyols and a carbonic ester and also a hydroxyl-containing (meth)acrylate or vinyl ether.
Examples of suitable carbonic esters include ethylene carbonate, 1,2- or 1,3-propylene carbonate, dimethyl carbonate, diethyl carbonate or dibutyl carbonate.
Examples of suitable hydroxyl-containing (meth)acrylates are 2-hydroxyethyl (meth)acrylate, 2- or 3-hydroxypropyl (meth)acrylate, 1,4-butanediol mono(meth)acrylate, neopentylglycol mono(meth)acrylate, glyceryl mono- and di(meth)acrylate, trimethylolpropane mono- and di(meth)acrylate, and pentaerythrityl mono-, di-, and tri(meth)acrylate.
Suitable hydroxyl-containing vinyl ethers are, for example, 2-hydroxyethyl vinyl ether and 4-hydroxybutyl vinyl ether.
Particularly preferred carbonate (meth)acrylates are those of the formula:
in which R is H or CH3, X is a C2-C18 alkylene group, and n is an integer from 1 to 5, preferably 1 to 3.
R is preferably H and X is preferably C2 to C10 alkylene, examples being 1,2-ethylene, 1,2-propylene, 1,3-propylene, 1,4-butylene, and 1,6-hexylene, more preferably C4 to C8 alkylene. With very particular preference X is C6 alkylene.
The carbonate (meth)acrylates are preferably aliphatic carbonate (meth)acrylates.
They further include customary polycarbonates known to the skilled person and having terminal hydroxyl groups, which are obtainable, for example, by reacting the aforementioned diols with phosgene or carbonic diesters.
Polyether (meth)acrylates are preferably (meth)acrylates of singly to vigintuply and more preferably triply to decuply ethoxylated, propoxylated or mixedly ethoxylated and propoxylated, and more particularly exclusively ethoxylated, neopentylglycol, trimethylolpropane, trimethylolethane or pentaerythritol.
In addition it is possible to use singly to vigintuply and more preferably triply to decuply ethoxylated, propoxylated or mixedly ethoxylated and propoxylated, and more particularly exclusively ethoxylated, glycerol.
Preferred polyfunctional, polymerizable compounds are ethylene glycol diacrylate, 1,2-propanediol diacrylate, 1,3-propanediol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, pentaerythrityl tetraacrylate, polyesterpolyol acrylates, polyetherol acrylates, and triacrylate of singly to vigintuply alkoxylated, more preferably ethoxylated, trimethylolpropane.
Polyether (meth)acrylates may further be (meth)acrylates of polyTHF having a molar weight between 162 and 2000, poly-1,3-propanediol having a molar weight between 134 and 2000, or polyethylene glycol having a molar weight between 238 and 2000.
In one preferred embodiment of the present invention there is no compound (C) present.
Where the coatings of the invention are cured not with electron beams but instead by means of UV radiation, the preparations of the invention preferably comprise at least one photoinitiator (D) which is able to initiate the polymerization of ethylenically unsaturated double bonds. Photoinitiators (D) may be, for example, photoinitiators known to the skilled person, examples being those specified in “Advances in Polymer Science”, Volume 14, Springer Berlin 1974 or in K. K. Dietliker, Chemistry and Technology of UV and EB Formulation for Coatings, Inks and Paints, Volume 3; Photoinitiators for Free Radical and Cationic Polymerization, P. K. T. Oldring (Eds), SITA Technology Ltd, London.
Suitability is possessed by those photoinitiators as described in WO 2006/005491 A1, page 21 line 18 to page 22 line 2 (corresponding to US 2006/0009589 A1, paragraph [0150]), which is hereby considered part of the present disclosure through reference.
Also suitable are nonyellowing or low-yellowing photoinitiators of the phenylglyoxalic ester type, as described in DE-A 198 26 712, DE-A 199 13 353 or WO 98/33761.
Typical mixtures comprise, for example, 2-hydroxy-2-methyl-1-phenylpropan-2-one and 1-hydroxycyclohexyl phenyl ketone, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide and 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzophenone and 1-hydroxycyclohexyl phenyl ketone, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide and 1-hydroxy-cyclohexyl phenyl ketone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide and 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2,4,6-trimethylbenzophenone and 4-methylbenzophenone or 2,4,6-trimethylbenzophenone, and 4-methylbenzophenone and 2,4,6-trimethylbenzoyldiphenyl-phosphine oxide.
Preference among these photoinitiators is given to 2,4,6-trimethylbenzoyldiphenylphosphine oxide, ethyl 2,4,6-trimethylbenzoylphenylphosphinate, bis(2,4,6-trimethylbenzoyl)phenyl-phosphine oxide, benzophenone, 1-hydroxycyclohexyl phenyl ketone, 1-benzoylcyclohexan-1-ol, 2-hydroxy-2,2-dimethylacetophenone, 2,2-dimethoxy-2-phenylacetophenone, and mixtures thereof.
The coatings of the invention comprise the photoinitiators (D) preferably in an amount of 0.05% to 10%, more preferably 0.1% to 8%, in particular 0.2% to 5%, by weight based on the total amount of the radiation-curable compounds (A) and (B) and also optionally (C).
The dispersions of the invention may comprise further customary coatings additives (E), such as flow control agents, defoamers, UV absorbers, sterically hindered amines (HALS), plasticizers, antisettling agents, dyes, pigments, antioxidants, activators (accelerants), antistatic agents, flame retardants, thickeners, thixotropic agents, surface-active agents, viscosity modifiers, plastifying agents or chelating agents and/or fillers.
The coatings of the invention may comprise 0% to 10% by weight, based on the sum of the compounds (A) and (B) and also optionally (C), of at least one compound (E).
Suitable stabilizers comprise typical UV absorbers such as oxanilides, triazines, preferably hydroxyphenyltriazine, and benzotriazole (the latter obtainable as Tinuvin® products from Ciba Spezialitatenchemie) and benzophenones.
These stabilizers can be used alone or together with, based on the sum of compounds (A) and (B) and also optionally (C), additionally 0% to 5% by weight of suitable free-radical scavengers, examples being sterically hindered amines such as 2,2,6,6-tetramethylpiperidine, 2,6-di-tert-butylpiperidine or derivatives thereof, e.g., bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate or preferably bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate.
Additionally it is possible for one or more thermally activatable initiators to be added, examples being potassium peroxodisulfate, dibenzoyl peroxide, cyclohexanone peroxide, di-tert-butyl peroxide, azobisisobutyronitrile, cyclohexylsulfonyl acetyl peroxide, diisopropyl percarbonate, tert-butyl peroctoate or benzpinacol, and also, for example, those thermally activatable initiators which have a half-life at 80° C. of more than 100 hours, such as di-tert-butyl peroxide, cumene hydroperoxide, dicumyl peroxide, tert-butyl perbenzoate, silylated pinacols, which are available commercially, for example, under the trade name ADDID 600 from Wacker, or amine N-oxides containing hydroxyl groups, such as 2,2,6,6-tetramethylpiperidine-N-oxyl, 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl, etc.
Further examples of suitable initiators are described in “Polymer Handbook”, 2nd ed., Wiley & Sons, New York.
Thickeners contemplated are, besides free-radically (co)polymerized (co)polymers, customary organic and inorganic thickeners such as hydroxymethylcellulose or bentonite.
Examples of chelating agents which can be used include ethylenediamineacetic acid and salts thereof, and also β-diketones.
Suitable fillers comprise silicates, e.g., silicates obtainable by hydrolysis of silicon tetrachloride, such as Aerosil R from Degussa, siliceous earth, talc, aluminum silicates, magnesium silicates, calcium carbonates, etc. Suitable stabilizers comprise typical UV absorbers such as oxanilides, triazines, and benzotriazole (the latter obtainable as Tinuvin R products from Ciba Spezialitatenchemie), and benzophenones. They can be used alone or together with suitable free-radical scavengers, examples being sterically hindered amines such as 2,2,6,6-tetramethyl-piperidine, 2,6-di-tert-butylpiperidine or derivatives thereof, e.g., bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate. Stabilizers are used usually in amounts of 0.1% to 5.0% by weight, based on the “solid” components comprised in the preparation.
The antimicrobial, radiation-curable coatings of the invention generally have the following composition in % by weight:
The coatings of the invention are particularly suitable for coating substrates such as wood, paper, textile, leather, nonwoven, plastics surfaces, glass, ceramic, mineral building materials, such as cement moldings and fiber-cement slabs, and, in particular, metals or coated metals. Preference is given to the coating of steel, especially medical steel, and plastics, more particularly acrylonitrile-butadiene-styrene (ABS) and polycarbonate (PC) plastics.
The antimicrobial, radiation-curable coatings of the invention are suitable with particular advantage for the coating of medical devices and articles, examples being laboratory tables, operating tables, work surfaces. and device surfaces.
The substrates are coated in accordance with customary methods that are known to the skilled person, involving the application of at least one coating composition having the constitution described above to the substrate that is to be coated, in the desired thickness, and the removal from the coating composition of any volatile constituents present. This process can be repeated one or more times if desired. Application to the substrate may take place in a known way, e.g., by spraying, troweling, knifecoating, brushing, rolling, roller-coating or pouring. The coating thickness is generally situated within a range from about 3 to 1000 g/m2 and preferably 10 to 200 g/m2.
To remove the volatile constituents present in the coating composition, the coating can optionally be dried following application to the substrate, drying taking place for example in a tunnel oven or by flashing off. Drying can also take place by means of NIR radiation, NIR radiation here meaning electromagnetic radiation in the wavelength range from 760 nm to 2.5 μm, preferably from 900 to 1500 nm.
Optionally, if two or more films of the coating material are applied one on top of another, a radiation cure may take place after each coating operation.
Radiation curing is accomplished by exposure to high-energy radiation, i.e., UV radiation or daylight, preferably light with a wavelength of 250 to 600 nm, or by irradiation with high-energy electrons (electron beams; 150 to 300 keV). Examples of radiation sources used include high-pressure mercury vapor lamps, lasers, pulsed lamps (flash light), halogen lamps or excimer emitters. The radiation dose normally sufficient for crosslinking in the case of UV curing is situated within the range from 80 to 3000 mJ/cm2.
Irradiation may also optionally be carried out in the absence of oxygen, e.g., under an inert gas atmosphere. Suitable inert gases include, preferably, nitrogen, noble gases, carbon dioxide or combustion gases. Irradiation may also take place with the coating composition being covered by transparent media. Transparent media are, for example, polymeric films, glass or liquids, e.g., water. Particular preference is given to irradiation in the manner as is described in DE-A1 199 57 900.
In one preferred process, curing takes place continuously, by passing the substrate treated with the preparation of the invention at constant speed past a radiation source. For this it is necessary for the cure rate of the preparation of the invention to be sufficiently high.
This varied course of curing over time can be exploited in particular when the coating of the article is followed by a further processing step in which the film surface comes into direct contact with another article or is worked on mechanically.
The invention is illustrated in more detail by means of the following, nonlimiting examples.
Unless indicated otherwise, parts and percentages indicated are by weight.
Determination of antimicrobial activity by fluorescence microscopy
50 ml of DSM 92 medium (=TSBY Medium, Deutsche Sammlung von Mikroorganismen and Zellkulturen GmbH) in an Erlenmeyer flask with chicane are inoculated with a single colony of Staphylococcus aureus ATCC 6538P and incubated at 190 rpm and 37° C. for 16 hours. The resulting preliminary culture has a cell density of approximately 108 CFU/ml, corresponding to an optical density of OD=7.0-8.0. Using this preliminary culture, 15 ml of main culture in 5% DSM 92 medium with an optical density of OD=1.0 are prepared.
Analogous cultures are prepared for testing with
500 μl of the main bacterial culture are stained in accordance with the manufacturer recommendation using 1.5 μl of Syto 9 fluorescent dye and 1.5 μl of propidium iodide fluorescent dye (Film Tracer™ LIVE/DEAD® Biofilm Viability Kit, from Invitrogen). 10 μl of this bacterial suspension are applied to the surface under investigation, and covered with a cover slip. A homogeneous film of liquid is formed, with a thickness of about 30 μm. The test substrates are incubated in the dark at 37° C. for up to 2 hours. After this time, >95% living bacterial cells are found on untreated reference substrates (including pure glass).
The test substrates are examined under a Leica DMI6000 B microscope with the cover slip facing the lens. Each test substrate is advanced automatically to 15 pre-defined positions, and images are recorded in the three channels of phase contrast (P), red (R) and green (G). The absorbance and emission wavelengths in the fluorescence channels are adapted to the dyes used. Bacteria with an intact cell membrane (living) are detected in the green channel, bacteria with a defective cell membrane (dead) are detected in the red channel. The total of all the bacteria is detected in the phase contrast channel. For each of the 15 positions, the number of bacteria in all 3 channels is counted. The percentage of dead bacteria is calculated either from the numbers in R/(R+G) or, if background fluorescence is observed in the green channel, from R/P. The percentage of dead bacteria is averaged over the 15 positions and reported as the result.
The log P(ow) values were calculated with the program ACD/PhysChem Suite, Version 12.01 from Advanced Chemistry Development, Inc. (ACD/Labs, Ontario, Canada).
500 parts of a trifunctional isocyanurate based on 1,6-hexamethylene diisocyanate (Basonat® HI100, BASF SE), 230 parts of hydroxyethyl acrylate, 2 parts of methylhydroquinone and 0.1 part of dibutyltin dilaurate were combined at room temperature and the reaction temperature was maintained by cooling and heating for 3 hours within a range from 80° C. to 85° C. The mixture was diluted with 150 parts of butyl acetate and the temperature was lowered to 50° C. Then 116 parts of aminopropyltriethoxysilane were added over the course of 60 minutes and reaction was allowed to continue for 3 hours. The result was a colorless urethane acrylate resin having an NCO (isocyanate) value <0.1%.
Preparation of urethane acrylate UA2:
In a three-neck flask with reflux condenser and stirrer, 624.78 g of Laromer® LR 9000 (commercial product from BASF SE, isocyanato acrylate containing allophanate groups and based on 1,6-hexamethylene diisocyanate, having an NCO value of 14.5-15.5%, a viscosity to DIN EN ISO 3219 (shear rate D) at 23° C. of 1000 to 1400 mPas, and a double bond density of about 3.5 mol/kg), 0.50 g of methylhydroquinone, and 1.00 g of 2,6-di-tert-butyl-p-cresol were mixed at room temperature. As a catalyst, 0.20 g of dibutyltin dilaurate was added to the thoroughly mixed initial charge. Added dropwise to this mixture at room temperature over the course of 4.5 hours were 245.22 g of 3-aminopropyltriethoxysilane. An exothermic reaction was observed, with the internal temperature climbing to 45° C. At the same time there was a rise in the viscosity of the reaction mixture. Accordingly, 300 g of butyl acetate were added. The reaction was continued at an internal temperature of 60° C. until the NCO value of the reaction mixture was 4.09%. Then 128.50 g of 2-hydroxyethyl acrylate were added dropwise over the course of 25 minutes. The reaction mixture was subsequently stirred at an internal temperature of 75° C. for two hours until the NCO value of the reaction mixture was 0.03%. The solids content of the urethane acrylate was 79.7%. The double bond density of the solvent-free urethane acrylate was 2.41 mol/kg.
Preparation of urethane acrylate UA3:
100 parts of a trifunctional isocyanurate (Basonat HI100, BASF SE), 49 parts of hydroxyethyl acrylate, 0.2 part of methylhydroquinone, and 0.05 part of dibutyltin dilaurate were combined at room temperature and the reaction temperature was maintained over the course of 4 hours, by cooling and heating, within a range from 80° C. to 85° C. The reaction batch was diluted with 16 parts of butyl acetate and discharged.
a) 10 parts of this reaction mixture were admixed with 2 parts of Tamol® Fix OK (BASF SE; quaternary cationic, oxyethylated oleylamine derivative with an OH number of 170) and 0.01 part of phenothiazine over the course of 60 minutes, and reaction was continued at 60° C. for 6 hours. Then 4.3 parts of butanediol monoacrylate were added. The result was a colorless urethane acrylate resin having an NCO (isocyanate) value <0.1%.
b) 10 parts of this reaction mixture were admixed with 2.8 parts of di(tridecyl)hydroxypropyl-methylammonium methylsulfate and 0.01 part of phenothiazine over the course of 60 minutes, and reaction was continued at 60° C. for 6 hours. Then 4.3 parts of butanediol monoacrylate were added. The result was a colorless urethane acrylate resin having an NCO (isocyanate) value <0.1%.
100 parts of the urethane acrylate UA1, 25 parts of monofunctional acrylates (reactive diluents), and 10 parts of octadecyldimethyl[(trimethoxysilyl)propyl]ammonium chloride are admixed with 2 parts of Irgacure® 500 (photoinitiator), applied to a slide in a dry film thickness of approximately 25 μm, and cured under a nitrogen atmosphere in an IST exposure unit at about 1400 mJ/cm2, and subsequently cured thermally at 100° C. for 30 minutes.
100 parts of the urethane acrylate UA1, 25 parts of monofunctional acrylates (reactive diluents), and 10 parts of octadecyldimethyl(trimethoxysilyl)propylammonium chloride are admixed with 2 parts of Irgacure® 500, applied to slides in a dry film thickness of approximately 25 μm, and cured under a nitrogen atmosphere in an IST exposure unit at about 1400 mJ/cm2−.
The antimicrobial activity of example 3 and comparative example 3 against Staphylococcus aureus ATCC 6538P was determined additionally in accordance with the standard JIS Z2801. In this test, a high antimicrobial activity, with R≧5, was found for both coatings. This showed (1) that the above-described fluorescence microscopy test possesses a very high threshold (substantially higher than in JIS Z2801) for the indication of antimicrobial activity, and therefore, in contrast to JIS Z2801, allows a distinction to be made between active and extremely highly active coatings. This showed (2) that the coatings from examples 1-3 have an extremely high antimicrobial activity.
100 parts of the urethane acrylate UA1, 25 parts of butanediol monoacrylate, and the parts indicated in examples 5A-F of octadecyldimethyl(trimethoxysilyl)propylammonium chloride were admixed with 2 parts of Irgacure® 500, applied to slides in a dry film thickness of approximately 25 μm, and cured under a nitrogen atmosphere in an IST exposure unit at about 1400 mJ/cm2−.
On the basis of example 5E, the broad activity spectrum of the antimicrobial coatings was demonstrated.
Ten parts each of the urethane acrylates UA3 a) and b) were admixed with 0.2 part of Irgacure® 500, applied to a slides in a dry film thickness of approximately 25 μm, and cured under a nitrogen atmosphere in an IST exposure unit at about 1400 mJ/cm2.
The pendulum damping was determined in accordance with DIN 53157. For this purpose, the radiation-curable compositions were applied with a wet film thickness of 400 μm to glass. The wet films were first flashed at room temperature for 15 minutes and then dried at 100° C. for 20 minutes. The films obtained in this way were cured at 100° C. in an IST coating unit (type M 40 2x1-R-1R-SLC-So inert) with 2 UV lamps (high-pressure mercury lamps type M 400 U2H and type M 400 U2HC) and with a conveyor-belt speed of 10 m/min under a nitrogen atmosphere (O2 content not more than 500 ppm). The radiation dose was about 1400 mJ/cm2. In embodiment a), curing took place only by radiant energy, as described above. In embodiment b), exposure to UV light took place first, as described above, with subsequent thermal curing to completion.
The antimicrobial properties show no significant change.
The table shows that the mechanical properties of the films (hardness) can be enhanced by subsequent thermal treatment without significant deterioration in the antimicrobial activity.
100 parts of the urethane acrylate UA1, parts of butanediol monoacrylate (BDMA) as per the table, and 8 parts of octadecyldimethyl(trimethoxysilyl)propylammonium chloride were admixed with 2 parts of Irgacure® 500, applied to slides in a dry film thickness of approximately 25 μm, and cured under a nitrogen atmosphere in an IST coating unit at about 1400 mJ/cm2, and conditioned at 100° C. for 30 minutes.
A mixture was prepared from 7 parts of octadecyldimethyl(trimethoxysilyl)propylammonium chloride and 7 parts of butanediol monoacrylate with 68 parts of a urethane acrylate prepared by reacting a trifunctional isocyanurate based on hexamethylene 1,6-diisocyanate (Basonat® HI100, BASF SE) with 2 mol of hydroxyethyl acrylate and 1 mol of aminopropyltriethoxysilane (based on NCO groups), and also with a further 18 parts of butanediol monoacrylate, and this mixture was admixed with 2 parts of Irgacure® 500, applied to slides in a dry film thickness of approximately 25 μm, and cured under a nitrogen atmosphere in an IST coating unit at about 1400 mJ/cm2. The slides were subsequently cured thermally at 100° C. for 30 minutes.
A mixture was prepared from 8 parts of octadecyldimethyl(trimethoxysilyl)propylammonium chloride and 8 parts of butanediol monoacrylate with 64 parts of a urethane acrylate prepared by reacting a trifunctional isocyanurate based on hexamethylene 1,6-diisocyanate (Basonat®HI100, BASF SE) with 2 mol of hydroxyethyl acrylate and 1 mol of aminopropyltriethoxysilane (based on NCO groups), and also with 18 parts of methacrylic acid, and this mixture was admixed with 2 parts of Irgacure® 500, applied to slides in a dry film thickness of approximately 25 μm, and cured under a nitrogen atmosphere in an IST coating unit at about 1400 mJ/cm2. The slides were subsequently cured thermally at 100° C. for 30 minutes.
Comparative example 4 shows that methacrylic acid as reactive diluent (B) does not exhibit an effect in accordance with the invention.
| Number | Date | Country | |
|---|---|---|---|
| 61591289 | Jan 2012 | US |
