CA2004407A1 - Liquid, radiation-curable coating composition for coating glass surfaces - Google Patents

Abstract

04 Nov. 1988 (0830z) Abstract of the disclosure Liquid, radiation-curable coating composition for coating glass surfaces The present invention relates to a liquid, radiation-curable coating composition which contains A) 56 to 89% by weight of at least one diethylenically unsaturated polyurethane optionally containing urea groups, B) 10 to 30% by weight of at least one ethylenically unsaturated monomer, C) 0.5 to 8% by weight of at least one photoinitiator, and D) 0.05 to 6% by weight of N-.beta.-aminoethyl-.gamma.-aminopro-pyltrimethoxysilane, .gamma.-aminopropyltrimethoxysilane, N-methyl-.gamma.-aminopropyltrimethoxysilane or triamino-modified propyltrimethoxysilane, the sum of components (A) to (D) in each case being 100%
by weight, and all % by weight data being based on the coating composition.
These coating agents are employed for coating glass surfaces, in particular optical glass fibers, and are distinguished by good adhesion, even on exposure to moisture.

Description

'7 4 Nov. 1988 (0830z) BASF Lacke und Farben AG

Liquid, radiation-curab~l~ coatinq om~positlon for coatinq qla~s surface~
The present invention relates to a liquid, radiation-curable coating compo~itioll for coating glas~
surfaces and containing A) 56 to 89% by weight, ba~ed on th~ coating compo-~ition, of at lea~t on~ diethylenically un~aturated polyurethane optionally containing urea group~, 0 B) 10 to 30~ by weight, ba~d on ~ha coating compo-sition, of at le3st one ethylenically un~ura~ed monomer, C) 0.5 to 8% by weight, base~ on tha coating compo ~ition, of at lea~t one photoinitiator, and 5 D~ 0O05 o 6~ by weight, ba~ed on the coating compo-sition, of an 21koxysilana, tha ~um of co~ponQnt~ (A) to ~D) in ea~h ca~e being 100%
by w~ight.
The present in~ention al~o relate~ to a proce~s for coating gla88 surface~, in particular op~ical gla~
iiber~,u~ingthes0radiation-curablecoatingcompo~ition~.
Optlcal gla~s fiher~ have achieved con~tantly increa~ing impor~ance in the Yec~,or of communications as optical waveguide ~i~er~. For thi~ application, it i~
absolutely nece~sary to protect the glass ~urface again3t mois~ure and abrasion. ~he glas~ ~iber3 are therefore provided, immsd~ately after production, with a pro~ecting paint coat.

3f~ )'7 Thu~, it i~ known~ for example, frcm EP-B-114,982 to p~ovide glas~ fibers fir~tly with ~ buffer coa ing (primer) which is ela~ic, but not very hard and not very tough~ and then to apply a radiation-curable top coat which ha~ high hardne~s and toughne3~. The two-laysred con~truction is intended to en~ure good protection of the optical fibers under mechanical load, even at low tem-peratures. A~ thQ top coat, radiation-curable coating compo~ition~ based on a polyurethane containing diethy-lenic end group~, a diethylenically un~aturated ester ofa diglycidyl ethes o~ a bi~phenol, and a monoethylenical-ly un~aturated monomer, the gla~ tran~itîon temperature of the homopolymer preparQd fro~ thi~ monomer beiny above 55C~ are employed in EP-~-114,9B2.
Howe~er~ gla~ fiber coatings of thi~ typs have the con~idQrable d~d~antage of only poor adhe~ion to the glas~ ~urface. In paxtlcular on exposure to moi~tuxa, th~3 adh~sion i8 further impaired, undex cextain circum~
~tance~ even ~o greatly that full lo~ of adhQsion on the gl~88 surfac~ occur~. The problem o~ poor adhe~ion of the coa~ing compo~ition~ to the gla~ ~urface i~ Xnown. In order to improve tho adhe~io~, organos~lane~; a~ adhesion promoters, are therefore freguen~ly added to the coating compo~itions. Thus, it i8 known, for e~ample, from 2S EP-~33,043 to add organosilanes, a~ sdhe3ion promoters, to radiation-curable coa~ing agen~ ba3ed on vinyl monomer~ and reactive polymers (not polyurethane~
being es~ential to the invention that eithex the vinyl monomer~ or the polymers hsva a thiirane ring. Example~

x~

_ 3 ~-mentioned of Ruitable compounds are ~-aminopropyltri-etho.~y~ilane, N,~-aminoethyl-~-aminopropyltrimetho~y-~ilane ~nd ~glycidylo ~ ropyltrime~ho~y~ilane. There is no mention in this application of the lo~ in adhe~ion of the glass fiber coating~ on exposura to moisture.
It is also known, from Japanese Patent 45,138/85 of 8 October 1985 (correspond-~ to Japane~e Praliminary Publishad Specification 42,244/80 of 25 ~arch 19803, to employ organosilane~ a~ adhasion promQters in radiation-curable gla~ fiber coating agents~ The film~forming component~ employed are polymer~ having azide group~.
~-methacryloxypropyltrimetho~y3ilane~ aminopropyltri-mQthoxysilane and ~-glycidyloxypropyltrimethoxy~ilane are me~tioned a~ ~uita~le ~ilane~. However, it i3 essential to Japane3e Patent 45,138 that the azide groups are incorporated into the polymar~ in order to inarease the curing rate. This publication too doe~ not therefore mention the problem of the effect of moisture on the adhe~ion og the glass fiber coating.
- ~inally, EP~A-149,741 disclose~ liq~id, radiation-curnble gla98 fiber coating agents which contain, be8Ldes a radiation-curable, polye~hylenically un~atura~ed polymoric compound, 0.5 to 5~, ~a~ed on tha coating compo~ition, o~ a polyalkoxysilane. Polyalkoxy-~ilanes which carr~ an organic ~ub~tituent which carrie~
a 3ingle acti~e amino or mercaptyl hydrogen a~om which is able to react with the ethylenically un~aturatad bond~ ln a Nichael addition are ~ui~able. An ~xample mentione~ of ~uitable ~ilanos i3 ~ mercaptopxopyltrimethoxysilane.

~C~ )'7 According to the teaching of EP-A-149,741, it is only po3sible to improve the adhesion even on exposure to moisture by u~ing silan~ of this type. By contra~t, compound~ usually employed a~ adhesion promoters, such a~, for example, y-aminopropyltriethoxy~ilane and N-~-(N-vinylbenzylaminopropyl~trimethoxysilane pro~e, according to EP-A-149,741, to be un~uitable for improving the adhe3ion on expo~ure to moistura~
The present invention therefore had the ob~ect o~
providing radiation~curable coating compo~i~ions for coa~ing glass surfaces, in particular optical glass fibers, in which the resultant coatingt after expo~ure to moisture, had only slight 1098 in adhe~ion, or none at all, compared with the corresponding fre~hly prepared coating examined Lmmediately aftar curing.
The ob~ect underlying the inYention i~ achieved by a liquid, radiation-curable coating composition for coating glas~ surface~ which contains A) 56 to 89% by weight, based on the coating compo-~ition, of at least one diethylenically unsaturated polyur~thane optionally containing urea group~, B) 10 to 30% by weight, basad on the coating compo-~ition, oP at least one ethylenically unsaturated monomer, C) 0.5 to 8% by weight, based on the coating compo-sition, of at lea~t one photoinihator tsic), D) 0.05 to 6% by weight, ba~ed on the coating compo-~ition, of an alkoxysilane, the sum o~ componsnts (A~ to ~D) in each case being 100%
by weight.
In the coating composition, component (D) i~
N-~-aminoethyl-~-aminopropyltxLmethoxy~ilane or ~-~mino-S propyltrimethoxy~ilane or N-methyl-7-aminopropyltri-methoxy~ilane or triamino-modified propyltrimethoxy-silane.
In view of the large number o~ organo~ilicon compound~ known a~ adhe~ion promoters, it was ~urprising and not for~eeable that the u~e of N-~-aminoethyl-~-aminopropyltr~methoxy~ilanQ, ~-aminopropyltr~methoxy-~ilane, N-methyl-~-aminopropyltrimethoxysilane a~d triamino-modified propyltrl~tho~ysilane tfor example DYNASYLAN~ adhesion promoter~, type "TRIAMO", co~mercial product fro~ Dyn~it-Nobel Che~ie) Lmpair~ the adhe~ion of radiation-curable coating agents ba~ed on unsatuxated polyurethanes on glass ~urace3 on expo~ure to moi~ure only insignificantly or not at all~ while con~iderable impairment in adhe~ion occur~ on exposure to moi~ture when other ~nown adheRion promoter~, such as, for exam-pl~ glyc~dyloxytrim2~he~ysilane and the monohydro-chloride o~ N~ N-~inylbenzylamino)ethyl~-aminopropyl-trLmethoxy~ilane, are u~ed.
The coaking compo~i~ivn according to the inven-tion i~ described below in greater detail~
The d~ethylenlcally un~aturated polyurethane~ (A)employed a~ tho film orming component can be obtained by reactlng a diisocyanate or polyi~ocyante with a chain extender from the group comprl~ing diol~Jpolyols a~d/or 6 - 27293-~7 diaminQ0~poly~mlne~ andJor di~hiol~ps:~lythiolY and~or alkanol~nine~ and ~ubse~quently reacting the frae isocya-nate groups which remalrl ~arith st lea~t on~ hydroxyalkyl acrylate or hydroxyalltyl es~er of other ethylenically un~turated carboxyllc acids.
The amount~ of chain extender~, diisocyanate or polyisocyar~ate ~Ind hydroxyalkyl e~ter~ of an e~hyleni~ally un~aturated carboxylic acid are ~el~c~ted her~ 30 that 1~ ) the~ equivalent ratLo between the NC0 g:roups and the roac~ivo group~ of the~ chain sxtender (hydroxyl~
~nlno or mercaptyl group~ betwe~n 3 :1 ænd 1: 2, and i~ preferably 2 s 1, arld 2. ) the OH groups of th~ hydroxyalkyl es~ar~ of e~ hyl-enic~lly unsatur~ ed carboxyllc acid~ ar~ pr~ent in ~ stoichiomatric amount relative to the ~till-r~e i~ocyanate group~ of 'che prepolymer m~de f rom i~o~yanate and cha~n extend~r.
~n addition, it i~ pos~ible to prepare ~he polyurethan~ (A) by fir~tly re~ctln~ ~ome o~ the isocya-2 0 na~e . group~ o~ a dii~ocyanate or polyisooyan2te with at le~s~ one hydroxyalkyl e~cer of an etllylenically un-sA~u~at0d c~rboxylic acld, and ~ub~sequently re~ctlng the rem~inin~ i80Cyl!ln~ltl~ s~roups wi~h ~ chain ext~nder. In thi~ oa~e too, the amount~ o:E ch~in extender, i~oc~anate 2S and hydroxyalkyl e~t~x~ o~ un~aturated c~arbo~rllc acids are ~elected so th~t the equlvalent rfltio between the NC0 groupo And ~h~ r~3activel group~ of the~ ohain ex~ender i~
be~w~en 3 s 1 and 1 t 2, ~nd i9 pre~e~xably 2 2 1, and ~he e~uivalent r~tio between the remnininy ~aCo group~ and the o~ group~ of the hydroxyalkyl ester is 1:1~
~ of cour~e po~sible to use all interm~diate form~ of these two proces~es. FGr example~ some o~ the isocyanate group~ of a diisocyanate can firstly be S reactad with a diol, more 3f the isocyanate groups can subsequently be reacted with the hydroxyalkyl ester of an ethylenically unsaturated carboxylic acid, and the remalning isocyanate groups can thsn be reacted with a diamine.
The~a various preparation processeR for polyure-thane~ are known (cf., for example, EP-A-204,161j and do not therefore require mor~ de ailed descriptionO
I~ocyanates which are ~uitable for preparation of the polyurethanes ~A3 are aromatic, aliphatic and cyclo-aliphatic dii~ocyanates and polyisocyanate~, such a3, for example, 2,4- and 2,6-toluylane diisocya~ate~ and mi~-ture3 ther~of, 4,4'-diphenyLmethane dii~ocyanate, m-phenylene diisocyanate, p~phenylene diisocyanate, 4,4~-diphenyl diisocyanate, 1,5-naphthalene dii~ocyanata, 1,4-naphthale~e di~ocyanate, 4,4'-toluidine diisocyanate, xylylene diiaocyanat~ and ~ub~ti~-uted aromatic ~y~tem~, ~uch 83, ~or example diani~idine diisocyanate~, 4,4'-diphenyl ether dii~ocyanateR or clorodiphenylene (~ic) dii~ocyanates~and hlgher-func~lonalaromatic isocyana~e~, such as, for example, 1,3,5-trii~ocyanatobenzene,4,4',4"-triisocyanattriphenylmethane (sic3, 2,4,6 trii~ocyanato toluene and 4,4~-diphenyldi~thylmsthane 2,2',5,5 tetxa-i.~ocyanate; cycloaliphatic l~ocyana~es, ~uch a~, for example, 1,3-cyclopontane dii~ocyanate, 1,4-cyclohexane ~ 0 0 ~

diisocyanate,1,2-cyclohexanediisocyandte,4,4'-methylene bis(cyclohexyl isocyanate) and i~ophorone dii~ocyanate;
aliphatic isocyanates, such a5, for example, tri-methy-lene diisocyanate, tetramethylene diisocyanate, penta-methylene d~isocyanate, hexamethylane diisocyanate,trimethylhexamethylene 1,6-dii~ocyanate and tris~hexa-methylene triisocyanate, and the diisocyanates derived from dimeric fatty acids described in EP-A-204,161, column 4, lines 42 to 49.
2,4- and 2,6-toluylene diisocyanate, 4,4'-diphenyl-methane dii~ocyanat0, hexamethylene diisocyanate, isopho-rone dii~ocyanate and 4,4'-methylene bis~(cyclohexyl iso-cyanate) are preferably employed.
Example~ o suitable diol~ and polyols are, for example, ethylene glycol, propylene 1,2-glycol and 1,3-glycol, butanediols, pentanediols, neopentyl glycol, hexanediol.~,2-methylpentane-1,5-diol,2-ethylbutane-1,4-diol, dimethylolcyclohexane, glycerol, trimethylolethane, trimethylolpropane and trimethylolbutane, e~ythritol, mesoerythritol, arabitol, adonitol, xylitol, mannitol, ~orbitol, dulcitol, hexanetriol, (poly)-pantaerythritol;
further monoethar~, ~uch a~ diethylene glycol and dipro-pylene glycol, and polyethex~, the adduc~ of the polyol~
mentioned and alkylene oxides. Exampl0~ of alkylene oxide~ ¦~héy-~ict¦are suitable for polyaddition to ~heYe polyols to form polyether~ are ethylene oxide, propylene oxide, butyl~ne oxide and styrene oxide. The~e polyaddi-tion products are generally called polyether~ having terminal hydroxyl group~. They may be linear or branched.

Example~ of polyethers of thi~ type are polyoxy~thylene glycol~ having a molecular weight of from 200 to 4,000, polyoxypropylene glycols having a molecular weight of from 200 to 4~000, polyoxytetramethylene glycol, poLyoxy-hexamethylene glycol, polyvxynonamethylene glycol,polyoxydecamethylene glycol, polyoxydodecamethylene glycol and mixture~ thexeof. Oth~r ~ype~ of polyo~yalky-lene glycol ethers may also be u~ed. Suitable polyether polyols are al~o those which are obtained by reacting polyol~ of this type, such a~ ethylens glycol, diethylene glycol, triethylene glycol, 1~4-butanediol, 1,3-butane~
diol, 1,6-hexanediol and mixtures thereof; glycerol trimethylolethane, trimethylolpropane 1,2,6-hexanetriol, dipsntaerythritol, tripentaerythritol, polypentaeryth-ritol, methyl glyco~ides and sucro~e, with alkyleneoxides, ~uch a3 ethylene oxide, propylene oxide or mixture~ thereof.
Examples of ~uitable polyether diols are al~o tha polymerization products of tetrahydrofuran or of butylene oxide. It i~ al50 po~ible to use polyestQr polyol~, preforably polyester diol~, which can be prepared, for example, ~y reacting the abovementioned glycol~ with dicarboxylic acids, ~uch a~, for example, phthallc acid~
i~ophthalic acid, hexahydroph~halic acid, adipic acid, azelalc acld, ~ebacic acid, maleic acid, glutaric acid, tetrachlorophthalic acid and hexachloroheptanedicar-boxylic acid. In~tead of these acids, it is al~o po~sible to use their anhydride~ if they exist.
It is also po3sible to use polycaprolactQne diol~

2 7 2 9 3~ ~ 7 ~nd trlols. ThesQ produot~ are obtain~d, for example, by reacting an ~-~aprolactonQ with a diol. Such product~ are d~ribed in US PatQnt 3 ,169, 945 .
The polylao~cone polyol~ ob~ain~sd by thi~ re~ction are di~tln~uish*d by the pr~en~e of a tsrmLnal hydroxyl group ~nd by recurring polye~t0r uni~ d~rlved from th~
l~c~one. ~rhe~s recurring molecular units may conform to the~ ~ormulfl o - C ~ (CHR)fl - CH20 ~

in wh~c:h n i~ pre~er~bly ~ to 6, and the Yubs~ tuent R is hyclrogen, an alkyl r~di~ll, a cycloalXyl radi~al or an alXoxy rad~l, no substltu~nt ~ont~ining more than 1~
oarbon a~com~ arld the total nwnber of carbon ai:om~ ~ n the ~ubs éituent in the la~ton~ ring nvt exceeding 12 .
~he l~oQe u~sed a~ atar~ing material CMn be any lactonQ or any combination of lactone~, but this l~ctene Jhould contaln at lela~t 6 carbon a~om~ in th6 ring, for exampl~ 6 to ~ carbon atom~, and at lea~t 2 hydrog~n sub~ cu~3nts ~hould be prQsen~ on ~h~ carbon atom bonded to the oxygon group ~ie the rirlg. The~ lac~one u~ed a4 ~tr,~rting m~lterl~l may b~3 repr~entecl by the genera.l ~ormul~ ~low.
f ,~ n O
o in which n and R axe es alr0ady de~ined abo~re. ~he 25 lac~one~ whlch ar~ pre~erred in the inven~ion ~or the preparatlon of th~3 polyester diol~ are caprolactone~ in whlch n h~ the v~luQ 4. ~he ~no~t-prePerr0d l~ctone i~
~ub~titued ~ ~caprolaotone ~ n whioh n ha~ the ~ralue 4 and all R ~ubstituent~ are hydrogen. Thi~ l~cton0 is particu-larly preferred ~ince it i~ a~r~ilabl~ in large amount~
and gives coating~ having excellent propertie~. In addition, various other la~tone~ c~n b~ us~d lndividually or in combinatlon.
Exampl~ss of ~1 f ph~tl~ diol3 which are ~ui tabl~
~0 for ~he re~csion wlth the lac~vn~ are th~ diol~ alre~dy men~lon~3d abov~ ~or the reac~lon with ~ha carbo~rll~
acid~ .
Examples of ~ui~able amllle~ are! ethylenediamine, tri-, t~'cra , p~nta- hexa~, he pta -, nona-, d~ca- and dodecaMethylenedlamirle, 2,2,4- and 2,4,4-tr~methylhexa-m~thy1~n~diamine, propylenediamine and the eorrespondin~
poly~lkylenadiamlnes, ~u~h a8, for ex~ple, polypropy-len0dla~inQ, polyether dl~mine~ having a molecular weight of from 200 to 4,000, for exa~pl~ polyoxy1ethylsnediamine (~ic~, polyoxypropylenQdiamine, polyoxy~etramethylenedi-amln~, 1,3~ And 1,4-buty1enediamlne, Lsophoronediamine, 1,2- a~d 1,4-di~minocy~lohe~ne, 4,4'-~iaminadLcyclohe~
methane, bl~-(3-m~thyl-4-~mino~yclohexyl)meth~ne, 2,2-biY(4-omLnocy~lohe~yl~propane, 4,7-dloxadecane-1,10-di~mino, 4,9-dlox~dodeeane-1,12-dl~mine, 7-methy1-4,-10-dioxa~ridecanQ~1,13-di~mine, nitrilotri3(ethane~
æmine), ethflnolAmlne, propanol~mlnQ, N-~2-amino-ethyl)e~hanol, poly0ther poly~mine~, bi~(3-aminopropyl)-methy1~min0, 3 amino-l-(methyl~m~no)propane, 3-~mi.no-1-2~

- 12 _ 27293-47 (cyclohe~yl~mino)propane, N~2-hydroxyethyl)ethylenedl-~mlne, ~rl~-~2-~mlnoQthyl)~mine, and polyamines of ~he formula H2N-(R2-NH~nRl~NH2. n i9 an integer between 1 ~nd 6, proferably 1-3. Rl ~nd R2 are iden~i~al or different ~lkylene groups or cycloalkylene gr~up~ or alXylene group3 containing ether groups, in each case having 2-~, pref~rably 2~4, C atom~. Ex~mple~ of polyalXylenepoly~
nmln~ of thl~ t~pe ~re d1ethylenetri~mln~, ~riethylene-tetr~mine, totra~thylenep~nt~min~, dipropylanetri~minel txipropyl~nete~ramine, t~trapropylenepentamin~ and dlbutylene~riamine.
Chain extender~ which ~an also be employed are dlthiol~ ~nd poly~hiol~, ~uoh as, for exampls, dith~o~
ethylene glycol, 1,2- and 1,3 propanedlthiol 9 butane-dlth~als, pent~n~dl~hiol~, hexanedithiol~ ~nd th~ otherS~ analogou~ compound~ of ~he diol~ and polyol~
m~ntloned.
Suitahle for introducing ~he ethyl~nically unJaturated group~ in~o the polyure~h~ne ar~ hydxoxy-~lkyl e~ter~ of ethyleni~ally unsa~ura~d ~arbo~ylicac~d~, ~uch as, or example, hydroxyethyl acrylate, hydroxypropylacrylate,hydroxybutylacryl~te,hydroxy~myl ~crylat~, hydroxyhexyl ~ryl~te, hydroxyoc~yl ~cryla~e ~nd tho correspondLng hy~roxyal~yl ester~ o~ m~th~cxylLc ~cid, fum~rlc ~cid~ m~le~c ~cid, it~conic nGi~ crotonic ncid, and l~ocrokonic ~cld.
~ h~ un~atur~ted polyur~th~n~ l~ employed in the coa~lng compo~ition~ in ~n ~mount o~ ~rom 56 to 89~ by welght, b~ed on ~he ~oatlng compo~ition.

~ e~ides the polyurethane (A~ ju~t de cribed, the coating agent accordi~g to ~he invention also contains 10 to 30~ by weight, based on the coating composition, of at least one ethylenically unsatuxated monomer (B). Examples of suitable monomer~ are ethoxyethoxyethyl acrylate, N-vinylpyrrolidone, phenoxyethyl acrylate, dim~thylamino-ethyl acrylate, hydroxyethyl acrylate; butoxyethyl acrylate, isobornyl acrylate, dLmethylacxylamide and dicyclopentyl acrylate. Also suitable are diacrylate~ and polyacrylat~s, such as, for example, butanediol diacry-late, trimethylo~propane diacrylate and triacrylate, pentaerythritol diacrylate and ~he long-chain linear diacrylate~ having a molecular weight of from 400 to 4,000, preferably 600 to 2,500, which are described in EP-A-250,631. For example, the two acrylate groups may be separated by a polyoxybutylene structure. It i~ al~o po~sible to employ 1,12-dodecyl diacrylats and the product of the reactlon of 2 mole~ of acrylic acid with one mole of a dimeric fatty alcohol, which genexally has 36 C atom~.
Mixtures o~ the monomer3 ~u~t de~cribed are al~o ~uit~ble.
Preferably employed are N-vinylpyrroliclone, phenoxyethyl acrylate, isobornyl acrylate ancl mixtures of thzse monomer~.
The photoinitiator employed in the coating compositions according to the invention in an amount of from 0,5 to ~% by weight, preferably 2 to 5% by weight, based on the coating compositionr varie~ with the X ~ 7 r~dl~tion amp10yed to ~ure thQ coatln~ agent~ t W radia-tion, e1ec~ron r~diati.on, vi~lble 1ight~. The coating composition~ according to the ~nvention ~re preferably cured by maanq of W radiation. In thi~ ca~e, k~ton~-S ba~d pho~olnltator~ ~re u~uall~ emp10yed, for examp1eacetophenon~, benzophenone, diethoxyacQtoph~none, m-chloroa~etopheQone, prop~ophenone, benzoin, b~nzil, ben211 dLm~thyl ket~19 anthraquinone, thixanthone ~1c) and thlox~n~hono dar1v~ti~s, ~nd mixtur~s of differens photolnitiator~.
Togeth~r with the photoinit1~or~ mentionedt var10u~ amines, for examp1e dlethylamin~ and triethanol-am1ne, can b~ emp10yed, if approprl~to, in ~mount~ of up to 4~ by weight, b~sQd on th~ ~o~ting ~ompo~itionJ and 8C~ a~ ~yn~rgis~.
A# the component Q~sentl~1 to the invention, the co~ting composition~ cont~in 0.05 to 6~ by weight, b~sed on the ~oating composi~ion~ of N-~-~mlnoethyl-7~am:ino-propyltrlm~tho~ysil~ne,~-~minopropyltr~me~hoxysilanQ,N-m~hyl~y-~mlnopropyltrLmethoxy~ilan~ortrl~mino~modified propyltrlmo~hoxy~llan~ (for ex~mple DYN~SYI~NP adhe~ion promot~r~, Ntyp~*R~AMO~, comM~rcial product ~rom Dyn~it Nob~l Ch~mLe). ~h~ lk~xy~ilan~s ~re commercially availabl~ product~ and therefore nsed not be d~crlbod in great~r detail. Preerre~ coating agents ar~ obtained by employing oither 0.5 to 2~ by weigh~, ~a~ed on the coating compo~ition, of N~-aminoethyl-~-aminopropyltrL-methoxysilane or 2 ~o 4~ by weight, bAsed on ~he co~ting compooltLon, of ~-aminoprepyl~rLm~ho~y~ilan~ or 3 ~o 5~

2~3~
- 15 ~
by weight, based on the coating composition, of N-methyl-~-~minopropyltrimethoxysilane or 4 to 6% by weight, basad on the coating composition, of triamino-modified propyl-trimethoxy~ilane ~for example DYNASYLAN~ adhe~ion promo-ters, "type TRIAMO"~ commercial product from Dynamit Nobel Chemie) a~ component (D).
The coating composition~ according to the inven-tion mayt if appropriate, additionally contain customary auxiliaries and addikives in cu~tomary amount~, prefe~-ably 0.05 to 10% by weight, based o~ the coating compo~i-tion. Examples of subskance~ of this type are flow agent~
and plasticizer~. The coating compo~ition~ may be applied to the glass ~ur~ace by means of known methods of appli cation, æuch a~, for e~amplel sprayingj rollingl flow-coating, dipping, knife coating or bru~hing.
- ~he paint films are cured by mean~ of radiation, pra~erably by means of W radiation. The equipment and condition~ for the~e method~ of curing are known fro~ the literature tcf., for example, R. Holmes, U.V. and E.B.
Curing Formulatiorl~ for Printing Ink~, Coatings and Paints, ~ITA Technology, Academic Pre~, London, United Kingdo~ 198~) and require no further de~cription.
The pre~ent invention al~o relate~ to a proce~
for coating a gla~ ~urface, in which I.~ a radiation curable coating composition is applied which contain~
~) 56 to 89~ by weight, ba~ed on the coatiny composi-tion, o~ at least one diethylenically un~aturated polyurethane optionally containing urea groups~

'7 B) 10 to 30% by weight, based on th coating compo~ition, of at least one ethylsnically un~aturated monomer, C) 0.5 to 8% by weight, based on the coatLng compo-sition, of at least one photoinitia~or, and D) 0.05 to 6~ by weight, based on the coating compo-sition, of an alkoxysilane, the qt~ of components (A~ to (D) in each ca~e being 100% by weight, and II.) the coating composition is cured by means of W or electron radia~ion.
In th~ proces~, the coating compo~ition contain3, a~ component (D), N-~ aminoethyl-~-aminopropyltrimathoxy-silane or y-aminopropyltrime~hoxysilane or N-methyl-~-lS aminopropyltrimethoxysilane or tri~mino-modified propyl-trLme~hoxysilane.
For a more detailed de~cription of the coating agent employed Ln the proces~ according to the invention and of the way in which thi~ proce~-q i~ carried out, reference is made to pages 5 to 13 of this de~cription.
The proce8 according to the invention i~ par-ticularly sultable for coating optical glaas fiber3. In particular when optical glas~ fibers ara used a~ optical waveguide8, it i~ important ~hat the coa~ing compositiQn~
applied to protect the ~urface have good adheslon to the gla~fl surfac0 even on expo~tlre to moisture. Lo~e~ in adhe~ion of ~he coating after exposure to moi~ture -which cannot be avoided when glas~ fiber8 ars u~ed a~
op~ical waveguides - (for example gla~ ~iber~ ars ~3~ '7 expo~ed to the air at coupling station~, result in paint damage on the glass fiber surface. This surface, which is then unprotected, can very easily be damaged, for example by grains of dust, which result3 in a loss in op~ical propertie~. The process according to the invention and the coating compositions according to the invention, in particular, make it possible, howevler, to ~void the~e disadvantages and to provide coating~ having very good adhesion, even after expo~ure to moisture.
The coating compositions according to the inven-tion can be applied to the glas3 fib~r either in the form of a 3ingle coat or as the prLmer of a two-coat sy~tem. Suitable top coat in the ca~e of the two-coat system are described, for exampla, in EP-B-114,982~
The invention i~ describ~d in greate-c detail in the example~ below. All part3 and percentage~ are by weight, unle~s expre~sly stated otherwise.
Example 1_15EEYb!E___nl A radiation-curable coating compo ition compris-ing ~5.8 part~ of unsaturated polyurethane, 9.2 parts of trimethylolpropane triacrylate, 12 part~ of phenoxyethyl acrylate, 0.5 part o~ benzll dimethyl ketal and 2.5 parts of benzophenone i~ prepared by known mathods (cf., for example, EP-B-114,982~, by firstly reacting 4 mole~ of 4,4'-methylene bis-(cyclohexyl i~ocyanate) with 2 moles of polyoxypropylene glycol (moleculAr weight 1,000) in the pre~ence o~ trimethylolpropane triacrylate and phenoxyethyl acrylate. Thi~ intermediate obtained i~
reacted with 2 mole~ o~ 2-hydroxyethyl acrylate and then ~ L~

with 1 mole of polyoxypropylenediamine (molecular weight 230~. The photoinitiatorA are then added to the mixture.
Thoxoughly purified lin parti.cular grea~e~free~
glass plates (width x length = 98 x 151 mm) are ma~ked a~
the edge with Te~akrepp adhesive tape No. 4432 (width 19 mm~, and tha coating composition is applied by knife coa~ing (dry film thickne~s 180 ~m).
The curing is carried out using a W irradiation apparatu~ equipped with two Hg medium-pressure lamps each with a lamp power of 80 W/cm, at a belt spesd of 40 m/minu~e, in 2 passes at half power (= 40 W~cm).
The incident dose here is 0.08 J/cm2 (mea,~ured using the do~imeter, WICURE, ~y~tem EIT from ~ltosch).
The adhesion is tested immediately thereafter a~
~ollow~:
~arefully datach the beginning of the foil from the gla~ using a razor blade.
- Attach a wire hook to the detached part of the foil u~ing adhesi~e tape .
0 - .Hook in a spring balance and xemove at right angle~
at the mo~t con~tan~ rate po~ibl0.
- Read ~ff the xemoval force requirad in g from the mea~urement scale.
The adhesion te~t i~ evaluated by averaging the value~ obtained from a double determination and checki~g the repreducibility of good (~ high~ adhesion values by ~everal repetition~.
The re ul~ of the adhe~ion te8t is ~hown in Table 1.

4~t7 27293-~7 ~ eside~ thiR adhe~ion te~t, which waR carried out, a roll peeling test in accordanc3 with DIN 55 289 i~
also possible/ but wa~ not carried out~
In order to test the adhe~ion after exposure ~o moi~ture, the glass plate~ wera a~ditionally ~tored for 12 hour~ after curing in ~uitable clLmatic chambar~
having a defined atmoqpheric humidity o~ 90~ relative atmospheric humidity (r.h.~ ~corrsspond.Lng to DIN 50005) at room temperature ~25C).
Immadiately aft~r compl~tion of exposure, the removal te-qt using the spring balance wa~ carried out analogouRly to the adhe~ion test Lmm~diately aft~r irradiation.
In this case too, the adhe~ion te~t wa~ evaluated by taking the average of a double determination. In the ca~e of good adhesion values, at le~st -two rep~at measurements were carr$ed out in order to check t~e reproducibility.
The result of thi~ test i~ likewise ~hown in Table 1.
The te~t carried out for adhesion to window gla~s gives good, meaningful xesults as a laborato~y method.
This method i8 also carried out at gla88 fiber manufac-~urer~ ~ince it giv~s ValUQ8 c108~ to those Ln pract,ice 2S which agree very well with the adhe3ion valu~s on optical gla8~ ~iber~ (typical ~iber thicknes~ 125 ~m).

~L
A radiation-curable coating agent based on the un~aturated polyurethane i8 prapared analogou~ly to 272~3-47 Comp4rlson Example 1, lrl contr~t to Comp~rl~s~n Exomple 1, tha co~ting agent ~dditlon~lly oont~ln~ 2~ by waight, b~sed on the tot~l compo~itlon, of ~-glycidyloxypropyl-trimetho~ysilane.
Analogou~ly to CornparL~on Ex,Ample 1, this coating ~gent i~ ~ppl ~ ed to gl~8~ plate~ by me~n~ of ~ knife co~ter (dry film thlckne~ 0 ~m) ~rld cured u~ng a mercury medlwn-pre~ure vapor lamp (do~e l~kewlse 0.08 J/cm2). rh~ ~dh~lon of the co~ting i~ me~su~-0 etit ~IZI dq~ncrlbed in Comp~rl~o~ Ex~mpl~ 1, ~nm~diately a~t~r curlng o~ the co~ting ~gent ~nd a~ter ~orage for 12 hours ~t 90~ rol~tlve atmo~pherlc humldley ~t room ~cemp~rature~. ~he reoult~ ~o ~hown in Ta~Dle 1.
Exam~le~ 3 an~d 4_~compAr~on~
lS Gla~s co~tlngs ~e prep~rad analogouæly to ~xnmpl~ 2r bu~ with the dlffer~nce th~t ~he 2~ by we~ght, based on the total composition, o~ t-glycidyloxypropyl-trLmethoxysll~n~ ~ro now repl~ced by 2~ by we~ght of 3-but~nyltrie~hoxy~ilan~ (Ex~mple 3~ or 2~ by wai~ht o~ ~he monohydrochloride of ~ 5N-viny~-N-benzylamino)ethyl~-~
amlnopropyltrlmothoxy~ilnne ~formula ~CH~O)JSi tC~2)3 NR ~CH2)2 NH~C~2~ ~ ~ CH ~ CH2 HCl tEx~mplo 4)/ ~ ch c~o ba~Qd on the totAl composit:lon.
Tha re~ult~ o~ the ~dhe~lon te~t aro shown in 2S ~ble 1.

Gl~ coa~clng~ ~re prep~red an~logou~ly to Exnmpl~ 2, bu~ with the dlfference th~t ~he 2% by weight of ~-glycLdylox~propyltxime~hoxy~ilane ~ra now replaced ~7 by 1 IExample S) or 2 ~Example 6) or 3 (Example 7) % by woight of N-~-aminoethyl-~-~minopropyltrimethoxysilane, in each case ba~ed on the total compo~ition.
Tha rasults of the adhe~ion tes~ are shown in Table 1.
Exam~le (sic) 8-9 Gla~s coating~ are prepared analogously to~
Example 2, but with the difference that the 2% by weight of ~-glycidyloxypropyltrimethoxysilane are now replaced by ~ (Example 8) or 4 (Example 9~ % by weight of N-methyl-~-aminopropyltrLmethoxysilane, in sach case based on the toal compo3ition.
Tho result~ of the adhe~ion test are shown in Table 1.
~i~DEihaL_L~:lL
Gla~ coating~ are prepared analo~ously to Example 2, but with the difference that the 2~ by weight of y-glycidylo~ypropyltrLmethoxy~Llane are now replaced by 2% byw eight of t-aminopropyltr~methoxy~ilane (E~ample 10) ~r 2% by weight of triamino-modlfied propyltri-methoxsilane ( 8iC ) ( DYN~5YLA~ adhe~ion promoters, type "TRIAMO", commercial product from Dyn~mit-Nobel Chemie), in each ca8a ba~ed on the ~otal composition.
The results of the adhesion ta3t are shown in ~S Table 1.

~ ~2 - 27293-~7 Table 1 ~r~lo ~-olon pro~ottr ~D~ ~unt o~ Adb~ n Adh~ COr ~D~ urlnll 12 ho~lr~ ~Ib ~ht 3 90~ r h.

- -1, 000- 1, 100 Z o-Clycl~Yloryprovylcr~ hoxy-no 2~,000-~, 100 ~0- ~00 0 9 3-~ut~nyLCrlotho~ 2900-1,000 2S-30 Monoh~drorblorld~ ot ~ n-vln~ n~yl~lno~-ChyL~7-~lno-propylcr~thu~ ne 2 7S0-1,000 1~0 l~-O-Aolno~hYl-7~lnopro~yLt~l-~-Choqrlhno 11,000~1,100 D00-1,000 O 11 J-h~lr,04Chyl~-~lnop~o~lerl-hor~ o 2~,000-1,100 900-1,000 7 1~ no-Ch~ 7~ no~rop~ rl-~otho~rll-n- 3800-1,900 800- 000 2 0 ~ N-Hoch~ ~Lno5tro~LCrl~otho~-n~ 211~0- 9~0 a~o- s~o I~ tb~L-7~ ,noproprltrl~hox~-1, 200~ 00~, 000- 1, 100 10 7-A~inop~o~lCrl0~tbo~eil-n- Z 1,000~1,150 7~0~ ~0 l~ Trl~lno~l~ ~d proprlcrl~
n~tbo~r-112no ~rRI~o~) 2 S,000-1, 100 S00 Example~ 1-11 show th~t only very low 1O9~ in ~dhs~ion, i~ any, oct:ur~ ~tor ~xpo~ure to mol~'cure of compo-sitions containing N-~,~ noe'chyl-t-~ninC)propyltr:lme*Ch-oxy~ ne, N-methy~ m1nopropylerim~tho;ty~l;an0, ~-aminop~opyltxlmethoxy~ n~ and trl~m~no-modi~10d p2-opy1-trimathoxy~ n~ (DYNASYI~ dhosion promoter~, type ~T~I~MO~, fxo~ ~yn~it ~obol Chemie)~ while con3iderable 10B~ in a~he~lon i~ ob~erve~ on expo~ur0 to mois~ure when o~her, known sil~ne ~dhesion promo~.ers, such ~, for ex~mple~ ~-glycidyloxypropyltrimethoxy~ ne, 3-butenyl-triethoxy~ ne and the monohydr w hlorids o~ N-~- ( N-vinylbenzylamino)~Ayl-y-~mlnopropyltrime~hoxy~ilane, ~re u.sed.

Claims (12)

1. A liquid, radiation-curable coating composition for coating glass surfaces and containing A) 56 to 89% by weight, based on the coating compo-sition, of at least one diethylenically unsaturated polyurethane optionally containing urea groups, B) 10 to 30% by weight, based on the coating compo-sition, of at least one ethylenically unsaturated monomer, C) 0.5 to 8% by weight, based on the coating compo-sition, of at least one photoinitiator, and D) 0.05 to 6% by weight, based on the coating compo-sition, of an alkoxysilane, the sum of components (A) to (D) in each case being 100%
by weight, wherein component (D) is N-.beta.-aminoethyl-.gamma.-aminopropyltri-methoxysilane or .gamma.-aminopropyltrimethoxysilane or N-methyl-.gamma.-aminopropyltrimethoxysilane or triamino-modified propyltrimethoxysilane.

2. A coating composition as claimed in claim 1, which contains 0.5 to 2% by weight, based on the coating composition, of N-.beta.-aminoethyl-.gamma.-aminopropyltrimethoxy-silane as component (D).

3. A coating composition as claimed in claim 1, which contains 2 to 4% by weight, based on the coating composition, of .gamma.-aminopropyltrimethoxysilane as com-ponent (D).

4. A coating composition as claimed in claim 1, which contains 3 to 5% by weight of N-methyl-.gamma.-amino-propyltrimethoxysilane as component (D).

5. A coating composition as claimed in claim 1, which contains 4 to 6% by weight of triamino-modified propyltrim-ethoxysilane as component (D).

6. A coating composition as claimed in one of claims 1 to 5, wherein monomer (B) is selected from N-vinylpyrrolidone phenoxyethyl acrylate, isobornyl acrylate and mixtures thereof.

7. A coating composition as claimed in one of claims 1 to 5, which additionally contains at least one synergist, customary auxiliary or additive.

8. A process for coating a glass surface, in which I) a radiation-curable coating composition is applied, and II) the coating composition is cured by means of UV or electron radiation, wherein the radiation-curable coating composition is a coating composition as claimed in one of claims 1 to 5.

9. The process as claimed in claim 8, wherein the glass surface is the surface of an optical glass fiber.

10. An optical glass fiber which is coated with a cured coating of a composition as claimed in one of claims 1 to 5.

11. The use of an optical glass fiber as claimed in claim 10 as an optical waveguide.

12. The use of a radiation-curable coating composition as claimed in one of claims 1 to 5 for coating optical glass fibers.