WO1997025378A1

WO1997025378A1 - RADIATION HARDENING OF α SUBSTITUTED VINYL ETHERS

Info

Publication number: WO1997025378A1
Application number: PCT/EP1997/000010
Authority: WO
Inventors: Wolfgang Reich; Reinhold Schwalm; Lukas HÄUSSLING; Erich Beck; Marc Heider; Oskar Nuyken; Roman-Benedikt Raether
Original assignee: Basf Aktiengesellschaft
Priority date: 1996-01-08
Filing date: 1997-01-03
Publication date: 1997-07-17
Also published as: DE19600342A1

Abstract

A process for producing coatings of the moulded articles by radiation hardening is characterised in that radiation-hardenable materials, which contain a quantity equivalent to 1-100 wt.% (of the total quantity of cationically and optionally radically polymerisable compounds) of α-substituted vinyl ethers with at least one vinyl ether group of formula (I) in which R1 stands for a C¿1?-C10 alkyl group or a C5-C10 aryl group or C5-C10 cycloalkyl group, are irradiated with high-energy light.

Description

Radiation curing of α-substituted vinyl ethers

description

The invention relates to a method for producing coatings and moldings by radiation curing.

Radiation curing of compounds that can be polymerized by free radicals or cationic polymerization is generally known. The radiation curing of acrylate compounds has gained particular technical importance. With acrylate compounds, however, there is basically the problem that the photopolymerization is inhibited by oxygen.

Since the problem of oxygen inhibition does not arise in the case of cationic photopolymerization, cationically polymerizable compounds could be an alternative to the free-radically polymerizable compounds. What is required, however, is a curing rate that is comparable to the free-radically polymerizable compounds, in particular the acrylate compounds, and the application properties of the coatings or moldings obtained that are as good as possible.

It is known e.g. the cationic photopolymerization of unsubstituted vinyl ethers. However, the relatively low reactivity of splitting off acetaldehyde, such as e.g. emerges from DE-A-4027437.

The cationic polymerization of α-substituted vinyl ethers is described in T. Masuda, T. Higashimura Makromol. Chemie 167, 191 (1973). At -78 ° C. and reaction times of several hours in the presence of iodine, iron chloride or acetic acid penchlorate as initiators for the cationic polymerization, homopolymers or copolymers could be obtained.

In A. Hult, S.A. Mac Donald, CC Willson, Macromolecules 18, 1804 (1985) describes a process in which a polymer matrix which contains a photoinitiator for cationic polymerization is irradiated with high-energy light and the surface treated in this way is cationically polymerizable monomers, 2-methoxypropenes were also used.

Furthermore, β-substituted vinyl ethers (1-propenyl alkyl ether), for example from JV Crivello, KD Jo, J. Polym. Be.; Part A; Polym. Chem. 31, 1473 (1993). These ^compounds' to show a low reactivity.

The object of the present invention was a process for the production of coatings or moldings by radiation curing, wherein oxygen inhibition does not occur or hardly occurs, the reactivity of the compounds used is as high as possible and the performance properties of the coatings and moldings obtained are satisfactory.

Accordingly, a process for the production of coatings or moldings by radiation curing, characterized in that radiation-curable compositions which are 1 to 100% by weight, based on the total amount of the compounds which can be cationically and optionally radically polymerized, have α-substituted vinyl ethers with at least one vinyl ether group formula

H ₂ C = C— O—

R ^l (I)

where R ^{1 is} a Ci-Cio alkyl radical or a C ₅ -C ₁₀ aryl radical or -cycloalkyl radical, are contained, are irradiated with high-energy light, found.

The α-substituted vinyl ethers contain at least one, preferably one to six, particularly preferably one to four vinyl ether groups of the formula I. In formula I, R ¹ preferably represents a C ¹ -C ₆ -alkyl radical and particularly preferably a methyl group .

α-substituted vinyl ethers with a group of formula I are e.g. those of the formula

H ₂ C = C - 0 - R ²

(II)

I.

R ^l

in which R ^{2 represents} a C ₁ -C ₂ alkyl radical or a C ₅ -Cio cycloalkyl or aryl radical. R ² is preferably a C 1 -C 6 -alkyl radical; in particular for an ethyl or propyl group or a cyclohexyl radical. α-εubstituierte vinyl ether with a plurality of ^"groups of formula I are those of the formula

(H ₂ C = C— 0— ⁾ _n R ³ (III)

R ^l

where n is an integer from 2 to 6, preferably from 2 to 4, and R ^{3 is} an n-valent organic radical having up to 30, preferably up to 20, in particular up to 10 carbon atoms. R ³ particularly preferably represents an n-valent hydrocarbon group, in particular a hydrocarbon chain, which can be interrupted by 1 to 10, preferably 1 to 5, particularly preferably 1 to 3 ether groups (-0-).

For example, α-substituted vinyl ethers of bifunctional alcohols such as ethylene glycol, propylene glycol and their more highly condensed representatives, e.g. such as diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol etc., butanediol, pentanediol, hexanediol, neopentylglycol, ethoxylated phenolic compounds, such as ethoxylated or propoxylated bisphenols, cyclohexanedimethanol,

of trifunctional alcohols, such as glycerol, trimethylolpropane, butanetriol, trimethylolethane and their alkoxylated representatives,

of multifunctional alcohols, such as pentaerythritol, ditrimethylolpropane, dipentaerythritol, sorbitol, mannitol and their alkoxylated representatives and of

Polyesterols made from di- or polyols and polyetherols with unsaturated or preferably saturated di- or polycarboxylic acids.

In the case of the bifunctional, trifunctional or polyfunctional alcohols mentioned, only part of the hydroxyl groups can be converted into the vinyl ether group. In particular, all of the hydroxyl groups have been converted into vinyl ether groups.

The preparation of the α-substituted vinyl ethers is known and can be carried out, for example, by reacting alcohols and acetylene

5 done.

The radiation-curable compositions used in the process according to the invention contain 1 to 100% by weight, preferably 5 to 100, particularly preferably 10 to 100% by weight and very particularly preferably 10 30 to 100% by weight, based on the cationically and optionally free-radically polymerizable compounds, the compounds of the formula I.

In particular, however, more than 50% by weight or more than 15 70% by weight of the cationically and optionally free-radically polymerizable compounds can be compounds of the formula I, or the polymerizable compounds can be exclusively compounds of the formula I act.

In addition to compounds of the formula I, further cationically polymerizable compounds include, in particular, linear or cyclic vinyl ethers, e.g. Vinyl methyl ether, vinyl ethyl ether, vinyl propyl ether, vinyl isobutyl ether, vinyl octadecyl ether, vinyl cyclohexyl ether and α-methyl vinyl alkyl ether.

25

In addition to compounds of the formula I, other cationically polymerizable compounds are also epoxides, e.g. Cyclopentene oxide, cyclohexene oxide, epoxidized polybutadiene, epoxidized soybean oil, Degacure K 126 (cyclic diepoxide) or glycidyl

30 ether, e.g. Butanediol diclycidyl ether, hexanediokiglycidyl ether, e.g. Biphenol-A-diglycidether, pentaerythritolbiglycidylether in consideration.

Cationically polymerizable monomers, such as unsaturated aldehydes and ketones, dienes such as butanediene, vinylaromatics such as styrene, N-substituted vinylamines such as vinylcarbazole, cyclic ethers such as tetrahydrofuran can also be used.

In addition to cationically polymerizable compounds, 0 free-radically polymerizable compounds or both free-radically and cationically polymerizable compounds can also be used. Worth mentioning are, for example, vinyl aromatics with up to 20 carbon atoms, vinyl esters of carboxylic acids with up to 20 carbon atoms and in particular (meth) acrylate compounds, as described, for example, by R. Holmann 5 UV and EB Curing Formulation for Printing Inks and Points, London 1984. In addition to monoacrylates such as Cχ-C ₂ o-alkyl (meth) acrylates, compounds with several (meth) acrylic groups are also particularly suitable.

For example, Trimethylolpropane triacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, hexanediol diacrylate or polyester, polyether, epoxy or urethane acrylates.

Examples of (meth) acrylate compounds include (Meth) acrylic acid esters of polyfunctional alcohols, in particular those which, apart from the hydroxyl groups, contain no further functional groups or at most ether groups. Examples of such alcohols are e.g. bifunctional alcohols such as ethylene glycol, propylene glycol, and their more highly condensed representatives, e.g. such as diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, etc., butanediol, pentanediol, hexanediol, neopentylglycol, alkoxylated phenolic compounds, such as ethoxylated or propoxylated bisphenols, cyclohexanedimethanol, trifunctional and higher-functional alcohols, such as glycerol, trimethanol trimethylol propane, trimethylol propane, trimethylol propane, trimethylol propane Ditrimethylolpropane, dipentaerythritol, sorbitol, mannitol and the corresponding alkoxylated, in particular ethoxy and propoxylated alcohols.

The alkoxylation products can be obtained in a known manner by reacting the above alcohols with alkylene oxides, in particular ethylene or propylene oxide. Preferably the degree of alkoxylation per hydroxyl group is 0 to 10, i.e. 1 mol of hydroxyl group can preferably be alkoxylated with up to 10 mol of alkylene oxides.

Other (meth) acrylate compounds which may be mentioned are polyester (meth) acrylates, which are the (meth) acrylic acid esters of polyesterols.

Examples of suitable polyesterols are those which can be prepared by esterifying polycarboxylic acids, preferably dicarboxylic acids, with polyols, preferably diols. The starting materials for such hydroxyl-containing polyesters are known to the person skilled in the art. Preferred dicarboxylic acids are succinic acid, glutaric acid, adipic acid, sebacic acid, o-phthalic acid, their isomers and hydrogenation products, and esterifiable derivatives, such as anhydrides or dialkyl esters of the acids mentioned. Suitable polyols are the above-mentioned alcohols, preferably ethylene glycol, 1,2 and 1,3 propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, cyclohexane dimethanol and polyglycols of the type ethylene glycol and propylene glycol into consideration.

Polyester (meth) acrylates can be used in several stages or in one stage, e.g. described in EP 279 303, can be prepared from acrylic acid, polycarboxylic acid, polyol.

Furthermore, compounds a) e.g. are epoxy or urethane (meth) acrylates.

Epoxy (meth) acrylates are e.g. those as can be obtained by reacting epoxidized olefins or poly- or diglycidyl ethers, such as bisphenol A diglycidyl ether, with (meth) acrylic acid.

The implementation is known to the person skilled in the art and e.g. in R. Holmann, U.V. and E.B. Curing Formulation for Printing Inks and Paints, London 1984.

Urethane (meth) acrylates are, in particular, reaction products of hydroxyalkyl acrylates with poly- or diisocyanates (see also R. Holmann, U.V. and E.B. Curing Formulation for Printing Inks and Paints, London 1984).

Mixtures of different compounds a), in particular also mixtures of the above (meth) acrylates, can of course also be used.

Preferred are (meth) acrylate compounds with 2 to 6, particularly preferably 2 to 4 (meth) acrylic groups. The molecular weight of the

(Meth) acrylate compounds is preferably less than 5000, particularly preferably less than 3000 g / mol. These are in particular polyester or polyether acrylates.

Unsaturated polyesters are also suitable as free-radically polymerizable compounds.

The content of free-radically polymerizable compounds in the radiation-curable compositions can e.g. 0 to 99, preferably 0 to 95, particularly preferably 0 to 90 and very particularly preferably 0 to 70% by weight, based on the total amount of the compounds which can be polymerized cationically and radically.

The α-substituted vinyl ethers of the formula I reduce even in small amounts, for example from 1% by weight, preferably 5% by weight and very particularly preferably from 10% by weight, based on the total amount of the compounds which can be polymerized cationically and radically , the Oxygen inhibition of (meth) acrylates during radiation curing. It is therefore also advantageous to use radiation-curable compositions which contain, for example, 1 to 50% by weight, preferably 5 to 40% by weight, of the vinyl ethers of the formula I and 99 to 50% by weight, preferably 95 to 60% by weight (Meth) acrylate, each based on the total amount of the cationically and free-radically polymerizable compounds, ent.

The radiation-curable compositions preferably contain a photoinitiator for photopolymerization.

The total amount of the photoinitiator is preferably 0.1 to 10, particularly preferably 0.5 to 5% by weight, based on the total amount of the compounds which can be polymerized cationically and optionally by free radicals.

Photoinitiators for cationic photopolymerization, when irradiated with UV light, give acids, called its e.g. Aryldiazonium, aryliodonium or arylsulfonium salts, disulfones, diazo-disulfones, imidotriflates, benzointosylates of the following structures:

®

Exemplary p-Methoxybenzoldiazoniumhexafluoro¬ be further phosphate, Benzoldiazoniumtetrafluoroborat, Toluoldiazoniumtetra- fluoroarsenat, diphenyliodonium hexafluoroarsenate, hexafluorophosphate Triphenylsulfo-, Benzolsulfoniumhexafluorophosphat, toluenesulfonic olsulfoniumhexafluorophosphat or Degacure KI85 (bis [4-diphenyl ^■ sulfonio-phenyl] sulfide-bis-hexafluorophosphate), isoquinolinium salts , Phenylpyridiniumsalze or Picoliniumsalze, such as M-ethoxy-isochinoliniumhexafluorophosphat, N-ethoxy-4-phenylpyri diniumhexafluorophosphat ^■ or N-ethoxy-2-phosphate picoliniumhexafluoro¬ mentioned. Ferrocenium salts (eg Irgacure 261 from Ciba) or titanocenes are also suitable. If the radiation-curable compositions also contain compounds which can be polymerized by free radicals, photoinitiators for free-radical photopolymerization are also preferably used, depending on the content of these compounds.

It is also possible to use photoinitiators exclusively for free-radical polymerization, in particular if the proportion of free-radically polymerizable compounds is greater than 30% by weight, based on the total amount of the polymerizable compounds.

Suitable photoinitiators for radical polymerization are, for example Benzophenone and derivatives thereof, e.g. Alkylbenzophenones, halogen-methylated benzophenones, Michler's ketone and benzoin and benzoin ethers such as ethylbenzoin ether. Benzyl ketals such as benzil dimethyl ketal, acetone phenone derivatives such as e.g. Hydroxy-2-methyl-l-phenylpropan-l-one and hydroxycyclohexylphenyl ketone. Anthraquinone and its derivatives such as methylanthraquinone and especially acylphosphine oxides such as e.g. Lucirin TPO (2,4,6-trimethylbenzoyldiphenylphosphine oxide) and bisacylphosphine oxides.

The radiation-curable compositions are used to produce coatings on the substrates to be coated, e.g. applied from wood, paper, plastic or metal or brought into the intended shape for the production of moldings.

The radiation-curable compositions can contain the additives customary for the respective purpose.

When used as a coating agent, this can e.g. Leveling agents, enhancers, pigments or fillers.

Radiation curing is preferably carried out with UV light. Suitable for this are e.g. UV lamp with a wavelength range of 240 to 400 nm and a power of 50 to 240 W / cm.

The radiation-curable compositions are particularly preferably suitable for the production of coatings on wood, plastic, paper, metal, where they are crosslinked by electron beams or, after the addition of photoinitiators, by UV radiation, i.e. be hardened and give coatings which meet the requirements for protective coatings or decorative coatings.

The radiation-curable compositions have a high reactivity, that is to say a high curing speed during radiation curing. The coatings or moldings obtained have good performance properties.

Examples of parts are parts by weight

Examples 1 to 6

2-ethoxypropene and the initiator given in the table are dissolved in methylene chloride. The concentration of the monomer is 3 mol / 1, that of the initiator 10 mmol / 1.

The reaction solution is irradiated with a mercury / xenon vapor lamp at the temperature given in the table and then precipitated in an ammoniacal methanol solution (5/95).

Example 7

2-methoxypropene and N-ethoxy-isoquinolinium hexafluorophosphate are dissolved in methylene chloride and irradiated with a mercury / xenon vapor lamp at room temperature. The mixture is then precipitated in an ammoniacal methanol solution (5/95). The polymer obtained is transparent and colorless; the average degree of polymerization P _n is 7 with a distribution M _w / M _n of 1.1.

Example 8

2-Cyclohexoxypropen and Irgacure 261 are dissolved in methylene chloride. The concentration of the monomer is 3 mol / 1, that of the initiator 10 mmol / 1. The reaction solution is irradiated with a mercury / xenon vapor lamp at room temperature and then precipitated in an ammoniacal methanol solution (5/95).

The conversion is 45% after 5 minutes and 95% after 1 hour.

The polymer obtained is colorless and transparent. It shows a bimodal distribution: the average degree of polymerization P _n is 5 or 28 with a distribution M _w / M _n of 1.1 or 1.2.

Example 9

2-ethoxypropene, ethyl acrylate and Lucirin TPO- (initiator for radical polymerization) are dissolved in toluene. The concentration of the monomers is in each case 1.5 mol / 1, that of the initiator 10 mmol / 1.

The reaction solution is irradiated with a mercury / xenon vapor lamp at room temperature and then precipitated in methanol.

The polymer obtained is crystal clear, colorless and of a very tough consistency. The ratio of vinyl ether to acrylate in the copolymer is 1: 5. The average degree of polymerization P _n is 39.

Example 10

The rate of polymerization of different vinyl ethers in methylene chloride was examined.

The concentration of the monomers was 3 mol / 1, that of the initiator (N-ethoxy-4-phenyl-pyridinium hexafluorophosphate) 10 mmol / 1. After 15 minutes of irradiation with a mercury / xenon vapor lamp, the following sales resulted (determined by the remaining monomer content):

x for comparison

Application engineering examples and tests

Example A)

(Parts are parts by weight)

A mixture of 5.5 parts of a cycloaliphatic diepoxide (Degacure K126, Degussa), 2.5 parts of a polycaprolactone (Capa 305 (OH number 310), Solvay Interox), 2.0 parts of butanediol diglycidether (Araldit DY 026 SP, Ciba Geigy) and 0.3 part of a 33% solution of bis [4-diphenylsulfonio) phenyl] sulfide-bis-hexafluorophosphate (initiator for the cationic polymerization) in propylene carbonate (Degacure KI 85, Degussa) is in one layer - thickness of 100 μm (wet) doctored and irradiated with UV light (2x80 W / cm) at a belt speed of 15 m / min and then post-cured for 10 min at 160 ° C.

Example B)

2.0 parts of tetraethylene glycol dipropenyl ether of the formula were used to mix Example A)

added and otherwise proceed as under A). Example C

100 parts of a polyester acrylate (Laromer® PE 55 F, BASF) are mixed with 4 parts of a photoinitiator (Irgacure 500, Ciba Geigy initiator for radical polymerization) and under UV light (2x80 W / cm) at a belt speed of 6. Irradiated 5 m / min.

Example D)

To the mixture under C) 20 parts Tetraethylenglykoldipro- penylether and 2 parts Degacure ^® K185 (initiator were added for cationic polymerization), and otherwise procedure described under C).

Example E)

100 parts of a polyester acrylate (Laromer PE 55 F, BASF) are mixed with 20 parts of tetraethylene glycol dipropenyl ether and 4 parts of a photoinitiator (Irgacure 500, Ciba Geigy) and under UV light (2x80 W / cm) at a belt speed of 6.5 m / min irradiated.

Application tests:

The pendulum hardness was determined according to DIN 53157 and is a measure of the hardness of the coating. The specification is made in seconds (S), whereby high values mean high hardness.

The Erichsen cupping was determined according to DIN 53156 and is a measure of flexibility, elasticity. The specification is made in millimeters (mm), high values meaning high flexibility.

The adhesion of the coating to substrates was determined using the grid cut test according to DIN 53 151. Low values indicate good adhesion.

In the tesa test, the adhesion was checked by applying and then peeling off a tape. Values from 0 to 5 indicate good to poor adhesion. Test results are given in the table.

example

after annealing the film at 160 ° C. for 1 hour

Claims

claims

1. A process for the production of coatings or moldings by radiation curing, characterized in that radiation-curable compositions which are 1 to 100% by weight, based on the total amount of the compounds which can be cationically and optionally radically polymerized, α-substituted vinyl ethers with at least a vinyl ether group of the formula

H ₂ C = C— 0- (I)

Rl

where R ^{1 is} a Ci-Cio alkyl radical or a C ₅ -Cio-aryl radical or -cycloalkyl radical, contain, are irradiated with high-energy light.

2. The method according to claim 1, characterized in that the proportion of the α-substituted vinyl ether is 5 to 100 wt.%.

3. The method according to claim 1 or 2, characterized in that the radical R ^{1 is} a Cχ-C ₆ alkyl radical.

4. The method according to any one of claims 1 to 3, characterized gekenn¬ characterized in that the radiation-curable compositions contain a photo-initiator for the cationic polymerization.

5. The method according to any one of claims 1 to 4 for the production of coatings on wood, paper, plastic or metal.

6. Coatings or moldings obtainable by a process according to one of claims 1 to 4.