EP0681562A1 - Radiation-hardenable oligomers and liquid, radiation-hardenable coating masses for glass surfaces - Google Patents

Abstract

Radiation-hardenable oligomers may be produced from (a) polyether triols or triamines, (b) polyether diols or diamines, (c) OH-functional acrylate monomers and (d) diisocyanates. The molar ratio (a) to (b) is comprised between 0.1 and 1.1, the molar ratio (c) to (a) is comprised between 2.0 and 10 and the equivalent ratio of the NCO groups in (d) to the hydroxyl or amino groups of the sum of (a) to (c) is comprised between 0.9 and 1.0. These oligomers are characterized in that at least one compound with 3 to 4 amino groups and a numeric mean molecular weight from more than 4,000 to 10,000 and/or at least one compound with 2 amino groups and a numeric mean molecular weight from more than 4,000 to 10,000 are used for their manufacture, and in that they contain 0.25 to 0.44 mol/kg double bonds.

Description

 5 radiation-curable oligomers and liquid, radiation-curable coating composition for coating glass surfaces

The present invention relates to radiation-curable oligomers with several ethylenically unsaturated end groups and several urea and optionally urethane groups per molecule, which can be prepared from

a) at least one hydroxyl and / or amino functional compound with a functionality between 3 and 4

b) at least one compound with 2 hydroxyl and / or amino groups per molecule,

C) at least one monoethylenically unsaturated compound with a group with one active hydrogen atom per molecule and with a number-average molecular weight between 116 and 1000 and

25 d) at least one aliphatic and / or cycloaliphatic diisocyanate,

Components a to d are used in such amounts that

1.) the molar ratio of component a to the component component b is between 0.1: 1 and 1.1: 1,

2.) the molar ratio of component c to component a is between 2: 1 and 10: 1 and

3.) the equivalent ratio of the isocyanate groups of component d to the amino and possibly hydroxyl groups of the sum of components a to c is between 0.9 and 1.0.

The present invention also relates to radiation-curable coating compositions which contain these radiation-curable oligomers and to processes for coating glass surfaces, in particular optical glass fibers, in which these coating compositions are used.

Optical glass fibers have become increasingly important in the field of communication as optical waveguide fibers. For this application it is absolutely necessary to protect the glass surface from moisture and wear and tear. The glass fibers are therefore provided with at least one protective lacquer layer immediately after their manufacture.

For example, it is known from EP-B-114 982 to first provide glass fibers with an elastic, but not very hard and less tough buffer layer (primer) based on linear urethane acrylates and then a radiation-curable topcoat likewise based on linear urethane acrylates to apply, which has a high hardness and toughness. The two-layer structure should ensure good protection of the glass fibers against mechanical stress even at low temperatures. However, coatings based on linear urethane acrylates have the The disadvantage is that the mechanical properties of the coatings, in particular the elasticity, are still in need of improvement.

Furthermore, EP-A-223 086 radiation-curable coating agents for the coating of optical glass fibers are known. These coating compositions contain, as binders, radiation-curable oligomers which can be prepared from polyether triols or triamines with an average molecular weight of 300 to 4000, polyether diols or diamines with an average molecular weight of 200 to 4000, OH-functional acrylate monomers and diisocyanates, the molar ratio of triol or triamine to diol or diamine used to prepare the oligomers being between 2.5: 1 and 20: 1.

These radiation-curable coating agents described in EP-A-223 086 are used either as a topcoat or as a one-coat coating. However, they are not suitable as a primer due to the too high modulus of elasticity of the hardened coatings.

Radiation-curable coating compositions for the coating of optical glass fibers are also described in EP-A-209 641. These coating compositions contain, as binders, a polyurethane oligomer with acrylate end groups, which is based on a polyfunctional core. These coating compounds can be used both as a primer and as a top coat. Single-layer processing is also possible.

From the international patent application with the publication number WO 92/04391, radiation-curable coating agents for the coating of optical glass fibers are known which are radiation-curable as binders

Oligomers according to the preamble of the main claim contain Due to the low modulus of elasticity, these coating agents are used in particular as primers for glass fibers. However, the manufacturers of optical glass fibers have demanded to further improve the mechanical properties of the coatings. In particular, the buffer effect of the coatings should be further optimized and the buffer properties should remain as constant as possible over a wide temperature range. The reactivity of the coating compositions should not be impaired and easy assembly of the coated glass fibers should be ensured.

The object of the present invention is to provide radiation-curable coating compositions for the coating of glass surfaces, in particular optical glass fibers, which, compared to the known coating compositions, result in coatings with improved properties. In particular, the cured coatings should have an improved buffer effect due to lower modulus of elasticity at higher elongation at break values, the buffer properties being supposed to remain approximately the same over the largest possible temperature range. This means that the mechanical properties of the coating should deteriorate as little as possible as the temperature drops. In particular, the modulus of elasticity should rise as little as possible as the temperature drops. The coating materials should harden as quickly as possible. In addition, the coating agents should enable improved assembly of the coated glass fibers. In particular at the connection points of various glass fibers, it is therefore necessary for the coatings to have reduced adhesion to the glass fiber in order to be easily removable in the connection area. On the other hand, the The coating on the glass fiber does not deteriorate too much when exposed to moisture in order to ensure that there is no delamination due to moisture exposure when the optical fiber ages.

The object is surprisingly achieved by radiation-curable oligomers with several ethylenically unsaturated end groups and several urea and optionally urethane groups per molecule, which can be prepared from

a) at least one hydroxyl and / or amino functional compound with a functionality between 3 and 4

b) at least one compound with 2 hydroxyl and / or .amino groups per molecule,

c) at least one monoethylenically unsaturated compound with a group with an active hydrogen atom per molecule with a number average molecular weight between 116 and 1000 and

d) at least one aliphatic and / or cycloaliphatic diisocyanate,

Components a to d are used in such amounts that

1. the molar ratio of component a to component b is between 0.1: 1 and 1.1: 1, preferably between 0.1 and 0.8,

2. the molar ratio of component c to component a is between 2.0: 1 and 10: 1, preferably between 2.5 and 10 and 3. the equivalent ratio of the isocyanate groups of component d to the amino and possibly hydroxyl groups of the sum of components a to c is between 0.9 and 1.0.

The radiation-curable oligomers are characterized in that

1.) as component a at least one a ino group-containing compound a- _{j ^} with a number average molecular weight of more than 4,000 to 10,000 and / or at least one amino and / or hydroxyl group-containing compound a ₂ with a number average molecular weight of 400 to 4,000 has been used

2.) as component b at least one amino group-containing compound h- _^ with a number average molecular weight of more than 4,000 to 10,000 and / or at least one amino and / or hydroxyl group-containing compound b ₂ with a number average molecular weight of 200 to 4000 has been used

3.) the oligomers have double bond contents of 0.25 to 0.44 mol / kg and

4.) at least one amino group-containing compound a- _{j ^} and / or b ^ has been used to prepare the oligomers.

The present invention also relates to radiation-curable coating compositions which contain these radiation-curable oligomers, and to processes for coating glass surfaces, in particular optical glass fibers. with which these coating compositions are used.

It is surprising and was not foreseeable that radiation-curable coating compositions based on the oligomers according to the invention form coatings with an improved buffer effect compared to conventional coatings, i.e. lower modulus of elasticity with higher elongation at break values. Another advantage is the good buffering effect of the coatings, even at low temperatures, since this solves the problem of so-called microbends. Furthermore, the coatings according to the invention are distinguished by good mechanical properties, such as e.g. tensile strength and elongation adapted to the intended use, and by a reduced adhesion of the coatings to the glass fiber, which enables improved assembly of the coated glass fibers. The adhesion of the coating does not deteriorate too much after exposure to moisture, so that it is ensured that, as the optical fiber ages, no delamination occurs due to exposure to moisture. Finally, the coating agents according to the invention harden quickly.

The radiation-curable oligomers according to the invention are now explained in more detail below:

It is essential to the invention that for the preparation of the oligomers compounds containing amino groups a ~ __ π ** - * - * - * with a functionality of 3 to 4 and with a number average molecular weight of more than 4,000 to 10,000, preferably of more than 4,000 up to 6,000 and / or difunctional compounds b.-L containing amino groups with a number average molecular weight of more than 4,000 to 10,000, preferably of more than 4,000 to 6,000, are used. Component a ₁ and / or component b- ^ compounds with secondary are preferred .Amino groups, especially polyethers with terminal secondary amino groups, are used. Polyalkoxylated triols having terminal, secondary .amino groups are particularly preferably used as component a. Examples of suitable as component a ^ _^ compounds containing primary .Aminogruppen derived from polyalkoxilier- th triplets aminofunctional Verbindun¬ are gen, such as those sold under the name JEFFAMINE "^ Texaco commercially available, such as

The secondary .amines used as component a ^ can be prepared, for example, by reacting the corresponding polyethers containing primary amino groups with aliphatic ketones, such as, in particular, methyl isobutyl ketone and subsequent hydrogenation of the ketimine formed. Polyethers suitable for this reaction and containing primary amino groups are, for example, the products available under the name JEFFAMIN * ^ from Texaco, such as JEFFAMIT ^ T 5000.

Also suitable as component a- ^ are those on the market available products, such as NOVAMI.N®N 60.

The amino-functional compounds derived from polyalkoxylated diols, such as JEFFAMINE ^ D 4000, for example, which are available under the name JEFFi ^ MIN ^ from Texaco, are used as component b- ^. The secondary amines used as component b ^ can be prepared analogously to the compounds a- ^ by reacting the corresponding polyether containing primary amino groups with aliphatic ketones, such as in particular methyl isobutyl ketone, and subsequently hydrogenating the ketimine formed. Suitable polyethers containing primary amino groups for this reaction are, for example, those listed under b- ^ JEFFAMI1® types.

Also suitable as component b- ^ are the products commercially available under the name NOVAMIl ^ from CONDEA Chemie GmbH, such as NOVAMIN®N 50.

Poly- alkoxylated diols with terminal, secondary amino groups are particularly preferably used as component b.

Furthermore, for the production of the invention

Oligomers, optionally also amino and / or hydroxyl group-containing compounds a ₂ with a functionality of 3 to 4, preferably 3, and with a number average molecular weight of 400 to 4,000, preferably 750 to 2,000, are used.

Examples of suitable amino and / or hydroxyl group-containing compounds a ₂ are polyoxyalkylated triols, such as, for example, ethoxylated and propoxylated triols, preferably ethoxylated triols, particularly preferably with a number average molecular weight greater than or equal to 1,000. Glycerol or trimethylolpropane, for example, are used as triols. Suitable as component a ₂ also _shows the corresponding amino-functional compounds, such as those derived from poly- alkoxylated triols amino-functional compounds. Examples are the products available under the name JEFFAMIN ** ^ from Texaco, for example JEFFAMIN - * - * ^* , T 403 and T 3000 and the products available under the name N0VAMI.N® from CONDEA Chemie GmbH, eg NOVAMI .N®N 30.

The amino-functional compounds a ₂ can contain both primary and secondary amino groups. In addition, compounds which contain both amino and hydroxyl groups are also suitable. For the preparation of the oligomers according to the invention it is also possible, if appropriate, to use compounds b ₂ containing amino and / or hydroxyl groups and containing two hydroxyl and / or amino groups per molecule.

These compounds b ₂ have number average molecular weights of 200 to 4,000, preferably 600 to 2,000.

Examples of suitable amino and / or hydroxyl group-containing compounds b ₂ are polyoxyalkylene glycols and polyoxyalkylene diamines, alkylene groups having 1 to 6 carbon atoms being preferred. For example, polyoxyethylene glycols with a number average molecular weight of 1,000, 1,500, 2,000 or 2,500 and

Polyoxypropylene glycols with the corresponding molecular weights and polytetramethylene glycols are suitable. Polyethoxylated and polypropoxylated diols can also be used, e.g. the ethoxylated or propoxylated derivatives of butanediol, hexanediol, etc., polyester diols which e.g. can be produced by reacting the glycols already mentioned with dicarboxylic acids, preferably aliphatic and / or cycloaliphatic dicarboxylic acids, such as e.g. Hexahydrophthalic acid, adipic acid, azelaic, sebacic and glutaric acid and / or their alkyl-substituted derivatives. Instead of these acids, their anhydrides, if they exist, can also be used.

Polycaprolactone diols can also be used. These products are obtained, for example, by reacting a £ -caprolactone with a diol. Such products are described in U.S. Patent 3,169,945.

The polylactone diols that are obtained by this reaction holds, are characterized by the presence of a terminal hydroxyl group and by recurring polyester portions derived from the lactone. These recurring molecular parts can be of the formula

- C - (CHR) _n - CH ₂

in which n is preferably 4 to 6 and the substituent is hydrogen, an alkyl radical, a cycloalkyl radical or an alkoxy radical, where no substituent contains more than 12 carbon atoms and the total number of carbon atoms of the substituents in the lactone ring does not exceed 12.

The lactone used as the starting material can be any lactone or any combination of lactones, this lactone should contain at least 6 carbon atoms in the ring, for example 6 to 8 carbon atoms and at least 2 hydrogen substituents on the carbon atom should be. The lactone used as the starting material can be represented by the following general formula:

in which n and R have the meaning already given. The lactones preferred for the preparation of the polyester diols in the invention are the caprolactones, where n is 4. The most preferred lactone is the substituted c-caprolactone, where n is 4 and all R substituents are hydrogen. This lactone is particularly preferred because it is available in large quantities and gives coatings with excellent properties. In addition, various other lactones can be used individually or in combination. Examples of aliphatic diols suitable for the reaction with the lactone are the diols already listed above for the reaction with the carboxylic acids.

Of course, the corresponding diamines and compounds with one OH and one amino group can also be used as component b ₂ . Examples of suitable compounds are the products available under the name JEFFAMIN®D 230, D 400, D 2000, ED 600, ED 900, ED 2001, ED 4000, BUD 2000 and C 346 from Texaco and those under the name NOVAMIN -δ products available from CONDEA Chemie GmbH, such as, for example, NOVAMI-Ni ^ N 10, N 20 and N 40.

A mixture of is preferred as component b ₂

* ° 2 _i ) ° ^b - * ^{s 90} mol% of at least one polyether diol and

b ₂₂ ) 10 to 100 mol% of at least one modified polyether diol

α) at least one polyether diol β) at least one aliphatic and / or cycloaliphatic dicarboxylic acid and v) at least one aliphatic, saturated compound with an epoxy group and with 8 to 21 C atoms per molecule, used, the sum of the proportions of components b ₂₁ and b ₂₂ and the sum of the proportions of components α to V each being 100 mol%.

To produce the modified polyether diols by the customary methods, components a to V "are used in amounts such that the equivalent ratio of the OH groups of component α to the carboxyl groups of component β is between 0.45 and 0.55, preferably 0.5 , and that the equivalent ratio of the epoxy groups of component Y ^* to the carboxyl groups of component ß is between 0.45 and 0.55, preferably 0.5.

Examples of suitable polyether diols b ₂₁ and α are the polyoxyalkylene glycols already listed, the alkylene groups having 1 to 6 carbon atoms. Component b _{21 is} preferably polyoxypropylene glycols with a number average molecular weight between 600 and 2,000. Polyoxibutylene glycols (poly-THF) with a number-average molecular weight> 1,000 are preferably used as component α.

As component β, aliphatic and cycloaliphatic dicarboxylic acids with 8 to 36 carbon atoms per molecule are preferably used, such as Hexahydrophthalic acid. Suitable components are, for example, epoxidized, monoolefinically unsaturated fatty acids and / or polybutadienes.

Preferred components of olcidyl esters are branched monocarboxylic acids, such as the glycidyl ester of versatic acid.

The compounds a- ^, a ₂ , b- ^ and b ₂ are preferably used in such amounts that the molar ratio of

Hydroxyl and / or amino groups of components a ₂ and b ₂ to the amino groups of components a- ^ and b- ^ is between 0 and 10, preferably between 0.1 and 3.

To introduce the ethylenically unsaturated groups into the polyurethane oligomer, monoethylenically unsaturated compounds with a group with an active hydrogen atom are used which have a number average molecular weight of 116 to 1,000, preferably 116 to 400. Examples of suitable components c are e.g. Hydroxyalkyl esters of ethylenically unsaturated carboxylic acids, e.g. Hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxibutyl acrylate, hydroxiamyl acrylate, hydroxhexyl acrylate, hydroxioctyl acrylate, as well as the corresponding hydroxyalkyl esters of methacrylate, fumaric acid, maleic acid, itacone croton acid and isocrotonic acid, although the hydroxy acid alkyl esters are preferred .

Adducts of caprolactone and one of the above-mentioned hydroxyalkyl esters of ethylenically unsaturated carboxylic acids are also suitable as component c. Adducts of the hydroxyalkyl esters of acrylic acid with a number average molecular weight of 300 to 1,000 are preferably used.

Aliphatic and / or cycloaliphatic diisocyanates, such as 1,3-cyclopentane, 1,4-cyclohexane, 1,2-cyclohexane diisocyanate, 4,4'-methylene, are suitable as component d for the production of the oligomers according to the invention bis (cyclohexyl isocyanate) and isophorone diisocyanate, trimethylene, tetramethylene, pentamethylene, hexethylene and trimethylhexamethylene-l _r 6-diisocyanate and those described in EP-A-204 161, column 4, lines 42 to 49, Diisocyanates derived from dimer fatty acids. Isophorone diisocyanate and trimethylhexamethylene-1,6-diisocyanate are preferably used.

Components a to d are used to produce the oligomers in such amounts that

1. the molar ratio of component a to component b is between 0.1: 1 and 1.1: 1, preferably between 0.1 and 0.8,

2. the molar ratio of component c to component a is between 2.0: 1 and 10: 1, preferably between 2.5 and 10, and

3. the equivalent ratio of the isocyanate groups of component d to the active hydrogen atoms from components a plus b plus c is between 0.9 and 1.0.

The oligomers according to the invention can be prepared in different ways. For example, it is possible first to react the diisocyanate d with the chain extenders a and b and then to react the remaining free isocyanate groups with the ethylenically unsaturated compound c.

It is also possible to prepare the oligomers by first reacting some of the isocyanate groups of component d with the ethylenically unsaturated compound c and then subsequently reacting the remaining free isocyanate groups with the chain extenders a and b.

It is also possible to prepare the polyurethane oligomers by the processes described in EP-A-223 086 on page 5. The polyurethane oligomers are preferably produced by means of a two-stage process in which the stoichiometric polyaddition of components a to d is carried out until more than 85% of the NCO groups of component d have reacted. In this first process step, components a to d are used in amounts such that the equivalent ratio of the NCO groups of component d to the active hydrogen atoms of components a to c is 1: 1.

In a second process step, the rest of the remaining components (corresponding to the desired NCO: OH ratio) are then added and the reaction is continued until the NCO groups have converted> 99%. In this second process step, further component c is preferably added and the desired NCO: OH equivalent ratio is set by adding this component c. In this preferred two-stage process, an adduct of hydroxyethyl acrylate and caprolactone with a number average molecular weight> .300 is preferably used as component c.

It is essential to the invention that the urethane oligomers have double bond contents of 0.25 to 0.44 mol / kg, preferably 0.3 to 0.44 mol / kg. Furthermore, the urethane oligomers according to the invention usually have number average molecular weights of 2,000 to 20,000, preferably 3,500 to 16,000 (measured with GPC against polystyrene standard), weight average molecular weights of 8,000 to 100,000, preferably 10,000 to 40,000 (measured with GPC) against polystyrene standard) and a functionality of 2 to 4, preferably 2.5 to 3.0, each per statistical average polymer molecule. The oligomers according to the invention are used as film-forming component A in radiation-curable coating compositions. The coating compositions usually contain 10 to 78% by weight, preferably at least 15% by weight and particularly preferably 63 to 73% by weight, based in each case on the total weight of the coating composition, of these oligomers according to the invention.

As a further constituent, the coating compositions can contain 0 to 60% by weight, preferably 0 to 50% by weight, in each case based on the total weight of the coating composition, of at least one further ethylenically unsaturated oligomer B. In addition to unsaturated polyesters, polyester acrylates and acrylate copolymers, urethane acrylate oligomers in particular are used, with the exception of the urethane acrylate oligomers used as component A. The type and amount of this component B can be used to control the properties of the cured coating in a targeted manner. The higher the proportion of this component B, the higher the elastic modulus of the cured coating in general. Component B is therefore added to the coating compositions especially when the coating compositions are used as a topcoat. The influence of this component B on the properties of the resulting coating is known to the person skilled in the art. The cheapest amount can be easily determined using a few routine tests. These ethylenically unsaturated polyurethanes used as component B are known. They can be obtained by reacting a di- or polyisocyanate with a chain extender from the group of the diols / polyols and / or diamines / polyamines and then reacting the remaining free isocyanate groups with at least one hydroxyalkyl acrylate or hydroxyalkyl ester of other ethylenic groups unsaturated carboxylic acids. The amounts of chain extender, di- or poly-isocyanate and hydroxyalkyl ester of an ethylenically unsaturated carboxylic acid are chosen so that

1. the equivalent ratio of the NCO groups to the reactive groups of the chain extender (hydroxyl, amino or mercaptyl groups) is between 3: 1 and 1: 2, preferably 2: 1, and

2. The OH groups of the hydroxyalkyl esters of the ethylenically unsaturated carboxylic acids are present in a stoichiometric amount in relation to the free isocyanate groups of the prepolymer composed of isocyanate and chain extender.

It is also possible to prepare the polyurethanes B by first reacting some of the isocyanate groups of a di- or polyisocyanate with at least one hydroxyalkyl ester of an ethylenically unsaturated carboxylic acid and then reacting the remaining isocyanate groups with a chain extender. In this case too, the amounts of chain extender, isocyanate and hydroxyalkyl ester of unsaturated carboxylic acids are chosen so that the equivalent ratio of the NCO groups to the reactive group of the chain extender is between 3: 1 and 1: 2, preferably 2: 1, and that Equivalent ratio of the remaining NCO groups to the OH groups of the hydroxyalkyl ester is 1: 1.

Of course, all intermediate forms of these two processes are also possible. For example, part of the isocyanate groups of a diisocyanate can first be reacted with a diol, then another part of the isocyanate groups with the hydroxyl alkyl ester of an ethylenically unsaturated carboxylic acid and then the remaining isocyanate groups can be reacted with a diamine.

These various methods of manufacturing the polyurethanes are known (cf. for example EP-A-294 161) and therefore do not require a more detailed description.

Compounds suitable for the production of these urethane acrylate oligomers B are the compounds already used in the production of component A and also the compounds mentioned in DE-OS 38 40 644.

In particular when the coating compositions according to the invention are used as a topcoat, aromatic structural components are preferably used to produce the urethane acrylate oligomers. In this case, 2,4- and 2,6-tolylene diisocyanate are particularly preferably used as the isocyanate component and aromatic polyester polyols based on phthalic acid and isophthalic acid and / or polypropylene glycol, ethylene glycol and diethylene glycol as chain extenders.

As a further constituent, the radiation-curable coating compositions also contain at least one ethylenically unsaturated monomeric and / or oligomeric compound C, usually in an amount of 20 to 50% by weight, preferably 22 to 35% by weight, in each case based on the total weight of the coating mass.

By adding this ethylenically unsaturated compound C, the viscosity and the curing speed of the coating compositions and the mechanical properties of the resulting coating are controlled, as is known to the person skilled in the art and is described for example in EP-A-223 086 and to which reference is made for further details.

Examples of monomers that can be used are ethoxyethoxyethyl acrylate, N-vinylcaprolactam, N-vinylpyrrolidone, phenoxyethyl acrylate, dimethylaminoethyl acrylate, hydroxyethyl acrylate, butoxyethyl acrylate, isobornyl acrylate, dimethyl acrylate and dicyclyl amide and dicyclyl amide. Di- and polyacrylates, such as e.g. Butanediol diacrylate,

Hexanediol diacrylate, trimethylol propane and triacrylate, pentaerythritol tria and tetra acrylate, the analogous acrylic acid esters of alkoxylated, especially ethoxylated and propoxylated, polyols, such as e.g. Glycerin, trimethylolpropane and pentaerythritol, with a number average molecular weight from 266 to 1014, and the long-chain linear diacrylates described in EP-A-250 631 with a molecular weight from 400 to 4,000, preferably from 600 to 2,500. For example, the two acrylate groups can be separated by a polyoxybutylene structure. It is also possible to use 1, 12-dodecyl diacrylate and the reaction product of 2 moles of acrylic acid with one mole of a dimer fatty alcohol, which generally has 36 carbon atoms.

Mixtures of the monomers just described are also suitable. Phenoxyethyl acrylate, hexanediol diacrylate, N-vinylcaprolactam and tripropylene glycol diacrylate are preferably used.

The photoinitiator typically used in the coating compositions according to the invention in an amount of 2 to 8% by weight, preferably 3 to 5% by weight, based on the total weight of the coating composition, varies with the jet used to harden the coating compositions lung (UV radiation, electron radiation, visible Light). The coating compositions according to the invention are preferably cured by means of UV radiation. In this case, ketone-based photoinitiators are usually used, for example acetophenone, benzophenone, α, α-dimethyl-α-hydroxiacetophenone, diethoxiacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, Hy - Droxipropylphenyl ketone, m-chloroacetophenone, propiophenone, benzoin, benzil, benzil dimethyl ketal, anthraquinone, thioxanthone and thioxanthone derivatives and triphenylphosphine and others as well as mixtures of various photoinitiators.

In addition, the coating compositions may also contain customary auxiliaries and additives. These are usually used in an amount of 0 to 4% by weight, preferably 0.5 to 2.0% by weight, in each case based on the total weight of the coating composition. Examples of such substances are leveling agents and plasticizers.

The coating compositions can be applied using known application methods, such as e.g. Spraying, rolling, flooding, dipping, knife coating or brushing, are applied to the substrate.

The coating films are cured by means of radiation, preferably by means of UV radiation. The systems and conditions for these curing methods are known from the literature (see, for example, R. Holmes, UV and EB Curing Formulations for Printing Inks, Coatings and Paints, SITA Technology, Academic Press, London, United Kindom 1984) and need no further description.

The coating compositions are suitable for coating various substrates, for example glass, wood, metal and plastic surfaces. In particular, they are used for coating glass surfaces, especially preferably used of optical glass fibers.

The present invention therefore also relates to a method for coating a glass surface, in which a radiation-curable coating composition is applied and cured by means of UV or electron radiation, which is characterized in that the coating compositions according to the invention are used as radiation-curable coating composition.

The method according to the invention is particularly well suited for the coating of optical glass fibers. The coating compositions according to the invention can be applied to the glass fibers in particular as a primer, but possibly also as a topcoat for a two-layer coating. When the coating compositions are used as a primer, the cured coatings usually have a modulus of elasticity (at 2.5% elongation and room temperature) of less than 10 MPa.

When the coating compositions are used as topcoat, the cured coatings usually have a modulus of elasticity (at 2.5% elongation and room temperature) of 500 to 1,000 MPa.

The invention is explained in more detail in the following examples. All parts and percentages are by weight unless expressly stated otherwise.

Production of a modified polyether diol

51.1 parts of polytetrahydrofuran with a number-average molecular weight are mixed in a kettle equipped with a stirrer, inert gas inlet and thermal sensor. weight of 1000 and an OH number of 118 mg KOH / g and 19.1 parts of hexahydrophthalic anhydride were heated to 120 ° C. and held at this temperature until an acid number of 102 mg KOH / g was reached. Then 0.02% chromium octoate, based on the weight of the mixture of poly-THF, hexahydrophthalic acid and glycidyl ester of versatic acid and 29.7 parts of the glycidyl ester of versatic acid with an epoxide equivalent weight of 266, are added. The mixture is heated to 120 ° C. until the reaction product has an epoxy equivalent weight> 20,000, an acid number of 4 mg KOH / g and an OH number of 60 mg KOH / g.

The modified polyether diol has an average molecular weight M _n = 1860 (calculated from the OH number), an M _n -V 1500 determined by means of GPC and an M _w / _n = 1.67. The viscosity of an 80% solution in butyl acetate is 3.8 dPas (measured at 23 ° C. with a plate / cone viscometer).

Comparative Example 1

As described in example 1 of international patent application WO 92/04391, 0.35 mol of a commercially available, ethoxylated trimethylolpropane with a number-average molecular weight of 1014 are in a kettle provided with a stirrer, inlet devices, thermal sensor and air inlet , 0.65 mol of commercially available polyoxypropylene glycol with a number-average

Molecular weight of 600, 0.65 mol of the modified polyether diol described above, 1.75 mol of hydroxyethyl acrylate, 0.05% dibutyltin dilaurate (based on the total weight of the sum of components a, b, c and d), 0.1 % 2,6-di-tert-butylcresol (based on the total weight of the sum of components a, b, c and d) and 30 ppm phenothiazine (based on the total weight of the sum of components a, b, c and d) and heated to 60 ° C. 2.70 moles of isophorone diisocyanate are then metered in at 50 ° C. in the course of 2.5 h. Then it is diluted with phenoxyethyl acrylate to a theoretical solid of 90% (sum of components a to d) and the temperature is kept at 60 ° C. until an NCO value of 1% is reached. Then 0.05% dibutyltin dilaurate and 0.51 mole of a commercially available hydroxyethyl acrylate caprolactone oligomer with a number average molecular weight of 344 (commercial product TONE M 100 from Union Carbide) are added at a temperature of 80 ° C. and the temperature kept at 80 ° C until an NCO value of <0.1% is reached. The oligomer thus obtained has a double bond content of 0.6 mol / kg and a functionality of 2.5.

A 40% solution (based on the theoretical solids content) of the oligomer 1 obtained in phenoxyethyl acrylate has a viscosity of 4.9 dPas (measured at 23 ° C. with the plate-cone viscometer).

A radiation-curable coating composition 1 is prepared from 66.8 parts of the urethane oligomer 1 described above, 29.3 parts of phenoxyethyl acrylate and 3.9 parts of α, α-dimethyl-α-hydroxiacetophenone.

Well cleaned (especially fat-free) glass plates

(Width x length = 98 x 161 mm) are taped off at the edge with Tesa crepe ^ adhesive tape No. 4432 (width 19 mm) and the coating compound 1 is crocheted on (dry film thickness

180 μm).

Curing is carried out with the help of a UV irradiation system, equipped with two Hg medium pressure lamps each with 80 W / cm lamp power, at a belt speed speed of 14 m / minute, in 1 pass at full load.

The irradiated dose is 0.15 J / cm ² (measured with the UVICURE dosimeter, System EIT from Eltosch).

The results of the modulus of elasticity determination at 0.5 and 2.5% elongation (according to the DIN 53 455 standard) and the results of the elongation at break test are shown in Table 3. In addition, Table 3 shows the glass transition temperature (measured with the aid of DMTA = dynamic mechanical thematic analysis) and the results of the adhesion test before and after moisture exposure. The liability test was carried out in accordance with DIN standard 53289.

example 1

In the kettle described in Comparative Example 1, 1.3 mol of the modified polyether diol described above, 1.75 mol of hydroxyethyl acrylate and 0.51 mol of a commercially available hydroxyethyl acrylate-caprolactone oligomer with a number-average molecular weight of 344 (commercial product TONE M 100 from Union Carbide) with 0.05% dibutyltin dilaurate (based on the total weight of the sum of components a, b, c and d), 0.1% 2,6-ditert.-butylcresol (based on the total weight of the sum of the components a, b, c and d) and 50 ppm phenothiazine (based on the total weight of the sum of components a, b, c, d) under a protective gas atmosphere (nitrogen / air = 3/1) and heated to 60 ° C. Thereafter, 2.70 mol of isophorone diisocyanate are metered in over the course of 2.5 h and the Tempe¬ temperature as long at 60 ^β C until an NCO value of 1.5% is reached. The mixture is then heated to 80 ° C. and the temperature is kept at 80 ° C. until an NCO value of 0.9% (theoretically 0.82%) is reached. A 40% solution (based on the theoretical solids content) of the product obtained in phenoxyethyl acrylate has a viscosity of 3.6 dPas (measured at 23 ° C. with a plate-cone viscometer). Then, at a temperature of 60 ° C., 0.35 mol of a commercially available propoxylated glycerol with an average of 3 secondary amino groups per molecule (number average molecular weight 5250, amino equivalent weight 2220 g, content of primary amino groups <0.02 mmol / g, commercial product) NOVAMI ^ NöO from Condea Chemie GmbH) so that the temperature does not exceed 65 ° C. The temperature is kept at 60 ^° C. until (possibly with <10% of the starting amount of polyether triamine to NCO content <0 , 1%) the NCO content is <0.1% The oligomer thus obtained has a double bond content of 0.42 mol double bonds / kg oligomer and a functionality of 2.5 (average number C = C / molecule) A 40% solution (based on the theoretical solids content) of the oligomer obtained in phenoxyethyl acrylate has a viscosity of 4.1 dPas (measured at 23 ° C. with the plate-cone viscometer).

Analogously to Comparative Example 1, a radiation-curable coating composition 2 is prepared from 66.8 parts of the urethane acrylate oligomer 2 described above, 29.3 parts of phenoxyethyl acrylate and 3.9 parts of α, α-dimethyl-α-hydroxiacetophenone.

The coating composition 2 is applied and cured analogously to Comparative Example 1. The test results of the coating obtained are shown in Table 3. Example 2

A radiation-curable oligomer 3 was produced analogously to Example 1, with the only difference that instead of 0.35 mol of NOVAMI1®N 60 0.35 mol of a commercially available, propoxylated glycerol with on average 3 primary amino groups per molecule (^ = 5000, amine equivalent weight 1890 g, commercial product JEFFAMIN-S-'T 5000 from Texaco) were used. After the addition of the isophorone diisocyanate, the temperature was kept at 60 ° C. until an NCO value of 1.8% was reached. Thereafter, the mixture was also heated to 80 ° C. and the temperature was held at 80 ° C. until an NCO value of 0.9% was reached. A 40% solution of the intermediate product thus obtained has a viscosity of 2.9 dPas, measured at 23 "C with the plate-cone viscometer using phenoxyethyl acrylate as solvent. The reaction with the amine is carried out analogously to Example 1. A 40% solution (based on the theoretical solids content) of the oligomer 3 obtained in phenoxyethyl acrylate has a viscosity of 5.1 dPas (23 ° C., plate-cone viscometer) ). The preparation, application and curing of the coating composition 3 is carried out analogously to Example 1. The test results of the coating obtained are shown in Table 3.

Comparative Example 2

A radiation-curable oligomer 4 was prepared analogously to Example 1, with the difference that instead of 0.35 mol of the polyether triamine with secondary amino groups (NOVAMIL> i * S>) N 60) in Comparative Example 2, 0.35 mol of a commercially available propoxylated Glycerins with an average of 3 primary .amino groups per Molecule with a number average molecular weight of 3,000 (amine equivalent weight 1060 g, commercial product JEFF-AMII-S T 3000 from Texaco) were used. After the addition of the isophorone diisocyanate, the temperature was kept at 60 ° C. until one

NCO value of 2.2% was reached. Thereafter, likewise if was heated to 80 ^β C and the temperature kept at 80 ^β C until an NCO value of 0.9% was reached. A 40% solution of the intermediate product of comparative example 2 thus obtained has a viscosity of 2.7 dPas, measured at 23 ° C. with the plate-cone viscometer using phenoxyethyl acrylate as solvent. The reaction with the .Amin is carried out analogously to Example 1.

A 40% solution (based on the theoretical solids content) of the oligomer obtained in phenoxyethyl acrylate has a viscosity of 4.6 dPas, measured at 23 ° C. with the plate-cone viscometer. The production, application and curing of the rays ¬ curable coating composition 4 is carried out analogously to Example 1. The test results of the coatings obtained are shown in Table 3.

Example 3

In the kettle described in Comparative Example 1, 0.65 mol of the modified polyether diol described above, 0.35 mol of a commercially available, ethoxylated trimethylolpropane with a number-average molecular weight of 1000, 1.75 mol of hydroxyethyl acrylate and 0.51 mol of a commercially available hydroxyethyl acrylate Caprolactone oligomers with a number average molecular weight of 344 (commercial product TONE M 100 from Union Carbide) with 0.05% dibutyltin dilaurate (based based on the total weight of components a, b, c and d), 0.1% 2,6-di-tert-butylcresol (based on the total weight of components a, b, c and d) and 50 ppm phenothiazine ( based on the total weight of components a, b, c and d) in a protective gas atmosphere (nitrogen / air = 3/1) and heated to 60 ° C. Then 2.70 mol of isophorone diisocyanate are metered in over the course of 2.5 h and the temperature is kept at 60 ° C. until an NCO value of 1.5% is reached. A 50% solution of the intermediate product thus obtained in phenoxyethyl acrylate has a viscosity of 6.7 dPas (measured at 23 ° C. with the plate-cone viscometer). Then, at a temperature of 60 ° C., 0.65 mole of a commercially available, propoxylated glycerin with an average of 2 secondary amino groups per molecule (number-average molecular weight 4150, amine equivalent weight 2350 g, content of primary amino groups <0.02 mmol) / g, commercial product NOVAMI-N ^ N 50 from Condea Chemie GmbH) so metered that the temperature-temperature does not exceed 65 C ^β. The temperature is kept at 60 ^β C until the NCO content (possibly with <10% of Aus¬ transmission amount polyether diamine NCO content <0.1% ein¬ ask) <0.1% by weight. The oligomer 5 obtained in this way has a double bond content of 0.414 mol / kg and a functionality of 2.5. A 40% solution (based on the theoretical solids content) of the oligomer obtained in phenoxyethyl acrylate has a viscosity of 3.7 dPas (measured at 23 ° C. with the plate-cone viscometer). The radiation-curable coating composition 5 is produced, applied and cured analogously to Example 1. The test results of the coating obtained are shown in Table 3. Comparative Example 3

Analogously to Example 3, a radiation-curable oligomer is produced with the only difference that instead of 0.65 mol of the polyether diamine with secondary amino groups with a number average molecular weight of 4150 (NOVAMINE ^ N 50), now 0.65 mol of a commercially available one ¬ Lichen polyoxypropylene diamine with primary amino groups with a number average molecular weight of 4000 (amine equivalent weight 2220 g, commercial product JEFFAMIN * - * 'D 4000 from Texaco) were used. A 40% solution (based on the theoretical solids content) of the oligomer obtained in 6 Phe¬ noxiethylacrylat has a viscosity of 6.6 dPas (measured at 23 C with the ^β cone and plate viscometer). The coating composition is prepared, applied and cured analogously to Example 1. The test results of the coating obtained are shown in Table 3.

Table 1: Composition of the oligomers in moles

Example MG El VI E2 V2 E3 V3 eth. TMP 1000 0.35 0.35 0.35

PE triamine l ^β 3000 0.35

PE-triamine 1 ° 5000 0.35

PE triamine 2 ° 5250 0.35

Polyoxypropylene 600 0.65 mod. PE 1860 1.30 0.65 1.30 1.30 0.65 0.65

PE diamine 1 "4000 0.65

PE diamine 2 ^β 4150 0.65

HEA 116 1.75 1.75 1.75 1.75 1.75 1.75

TONE M 100 344 0.51 0.51 0.51 0.51 0.51 0.51

IPDI 222 2.70 2.70 2.70 2.70 2.70 2.70

The following abbreviations were used in Table 1:

eth. TMP: ethoxylated trimethylolpropane PE-triamine 1 'propoxylated glycerol with primary amino groups

PE-triamine 2 ° propoxylated glycerol with secondary amino groups

mod. PE: modified polyether diol

PE-diamin 1 °: polyoxypropylene diamine with primary amino groups

PE-diamine 2 °: polyoxypropylene diamine with secondary amino groups

HEA: 2-hydroxyethyl acrylate

TONE M 100: Hydroxyethyl acrylate caprolactone oligomer

IPDI: isophorone diisocyanate

Table 2: Key figures of the oligomers

| El VI E 2 V2 E 3 V3

Molar ratio a / b 1 0.27 0.27 0.27 0.27 0.27 0.27 Molar ratio c / a 1 6.46 6.46 6.46 6.46 6.46 6.46 Molar ratio OH / NH (from a, b) 1 2.48 - 2.48 2.48 1.81 1.81 equivalent ratio NCO / (OH + NH) ^ 1 0.91 0.91 0.91 0.91 0.91 0.91 DBG [mol c = C / kg] 1 0.42 0.745 0.422 0.498 0.414 0.422 funct. C = C / molecule] 1 2.5 2.5 2.5 2.5 2.5 2.5 Viscosity (40% in POEA 23 ° C) 1 4.10 4.90 5.10 4.60 3, 70 6.60 [dPas]

) Calculated on the condition that NH ₂ = NH.

Table 3: Test results of the coatings (coating composition in each case from 66.8 parts by weight of urethane acrylate oligomer, 29.3 parts of phenoxyethyl acrylate and 3.9 parts of α, α-dimethyl-ct-hydroxiacetophenone)

El VI E 2 V2 | E 3 V3

Young's modulus (0.5% elongation) [MPa) 0.99 3.04 1.22 1.43 | 0.74 1.04 modulus of elasticity (2.5% elongation) [MPa] 1.02 2.94 1.21 1.49 | 0.79 1.12 Elongation at break [%] 58 27 51 38 | 58 55

Glass transition temp. Tg [ ^β C] -41 -19 -38 -31 | -57 -51 liability 50% rel. Humidity [N] 0.80 0.40 0.40 0.40 | 0.37 0.60 95% rel. Humidity [N] 0.40 0.20 0.30 0.20 | 0.20 0.30

Summary of test results

As the comparison of Examples 1 and 2 with Comparative Examples 1 and 2 and the comparison of Example 3 with Comparative Example 3 shows, when using amino group-containing chain extenders with a number average molecular weight M _n of more than 4,000, the buffering effect the resulting coating significantly improved. For example, the coatings of Examples 1 and 2 according to the invention have a number-average molecular weight of only when using an amino group-containing chain extender compared to the analogue structure

3,000 produced coating of comparative example 2 significantly reduced modulus of elasticity with simultaneously increased elongation at break and significantly reduced glass transition temperatures, with the use of chain extenders with secondary amino groups

(Example 1) brings a further improvement in the mechanical properties of the coatings compared to chain extenders with primary amino groups (Example 2). Also the comparison of example 3 with the analog one

Comparative Example 3, in which a primary amine with a number average molecular weight of 4,000 was now used instead of the A ins according to the invention with a number average molecular weight of 4,150, confirms the improved mechanical properties of the coatings according to the invention.

Claims

Patent claims: 1. Radiation-curable oligomers with several ethylenically unsaturated end groups and several urea and possibly urethane groups per molecule, which have been produced from a) at least one amino- and/or hydroxy-functional compound with a functionality between 3 and 4, b) at least one compound with two hydroxyl and/or amino groups per molecule, c) at least one monoethylenically unsaturated compound with a group with one active hydrogen atom per molecule and with a number average molecular weight between 116 and 1000 and d) at least one aliphatic and/or cycloaliphatic diisocyanate, where components a to d have been used in such amounts that 1.) the molar ratio of component a to component b is between 0.1: 1 and 1.1: 1, 2.) the molar ratio of component c to component a is between 2: 1 and 10: 1 and 3.) the equivalent ratio of the isocyanate groups of component d to the amino and possibly hydroxyl groups of the sum of components a to c is between 0.9 and 1.0, characterized in that, 1.) as component a, at least one compound a ₁ containing amino groups with a number-average molecular weight of more than 4,000 to 10,000 and / or at least one compound a ₂ containing amino and / or hydroxyl groups with a number-average molecular weight of 400 to 4,000 have been deployed, 2.) at least one amino group-containing compound b-^ with a number-average molecular weight of more than 4,000 to 10,000 and/or at least one amino- and/or hydroxyl-group-containing compound b ₂ with a number-average molecular weight of 200 to 4,000 has been used as component b , 3.) the oligomers have double bond contents of 0.25 to 0.44 mol/kg and 4.) at least one amino group-containing compound a-^ and/or ^ has been used to produce the oligomers. 2. Radiation-curable oligomers according to claim 1, characterized in that the oligomers have double bond contents of 0.3 to 0.44 mol/kg. 3. Radiation-curable oligomers according to claim 1 or 2, characterized in that as component a-^ amino group-containing compounds with a number-average molecular weight of more than 4,000 to 6,000 and / or as component b-^ amino-group-containing compounds. of more than 4,000 to 6,000 have been deployed. 4. Radiation-curable oligomers according to one of claims 1 to 3, characterized in that as component a ₂ amino- and / or hydroxyl-containing compounds with a number-average molecular weight of 750 to 2,000 and / or as component b ₂ amino- and / or hydroxyl-containing compounds with a number-average molecular weight of 600 to 2,000 and/or as component c, compounds with a number-average molecular weight between 116 and 400 have been used. 5. Radiation-curable oligomers according to one of claims 1 to 4, characterized in that as component aL and / or b- _j^ compounds with secondary amino groups, preferably as component a-^ polyalkoxy- lated triols with terminal, secondary amino groups and/or preferably poly-alkoxylated diols with terminal, secondary amino groups have been used as component b^. 6. Radiation-curable oligomers according to one of claims 1 to 5, characterized in that compounds containing hydroxyl groups have been used as component a ₂ and / or b ₂ . 7. Radiation-curable oligomers according to one of claims 1 to 6, characterized in that the molar ratio of the hydroxyl and / or amino groups of components a ₂ and b ₂ to the amino groups of components a - ^ and b - _j _ between 0 and 10, preferably between 0.1 and 3. 8. Radiation-curable oligomers according to one of claims 1 to 7, characterized in that as a component a-^ and/or a ₂ compounds with a functionality of 3 have been used. 9. Radiation-curable oligomers according to one of claims 1 to 8, characterized in that components a to d have been used in such amounts that 1.) the molar ratio of component a to component b is between 0.1 and 0.8 and/or 2.) the molar ratio of component c to component a is between 2.5 and 10. 10. Radiation-curable coating composition, characterized in that it contains at least one radiation-curable oligomer according to one of claims 1 to 9. 11. Radiation-curable coating composition according to claim 10, in particular for the buffer coating of optical glass fibers, characterized in that it A) 10 to 78% by weight of at least one radiation-curable oligomer according to one of claims 1 to 9, B) 0 to 60% by weight of at least one further ethylenically unsaturated oligomer, C) 20 to 50% by weight of at least one ethylenically unsaturated monomeric and/or oligomeric compound, D) 2 to 8% by weight of at least one photoinitiator and E) 0 to 4% by weight of common auxiliaries and additives contains, the percentages by weight being based on the total weight of the coating composition. 12. Radiation-curable coating composition according to claim 10, characterized in that it A) at least 15% by weight of at least one radiation-curable oligomer according to one of claims 1 to 9, B) 0 to 50% by weight of at least one further ethylenically unsaturated oligomer, C) 22 to 35% by weight of at least one ethylenically unsaturated monomeric and/or oligomeric compound, D) 3 to 5% by weight of at least one photoinitiator and E) 0.5 to 2.0% by weight of common auxiliaries and additives contains, the percentages by weight being based on the total weight of the coating composition. 13. Process for coating a glass surface, in particular a glass fiber, in which 1) a radiation-curable primer is applied and hardened using UV or electron radiation and 2) a radiation curable top coat applied and is hardened using UV or electron radiation, characterized in that a radiation-curable coating composition according to one of claims 10 to 12 is used as the primer and/or top coat. 14. Optical glass fiber, characterized in that it is coated with a radiation-curable coating composition according to one of claims 10 to 12.