DE19539294A1 - Production of coatings and moulded products by radiation curing - Google Patents

Abstract

A process for the production of coatings or moulded products by radiation curing, in which radiation-curable materials (I) containing 1-100 wt% compounds (A) with at least one cationically polymerisable 2,3-dihydrofuran (DHF) base unit (based on the total amt. of cationically and optionally radically polymerisable compounds) are irradiated with high-energy light. Also claimed are (i) radiation-curable materials (I), and (ii) compounds with 2 or more DHF units.

Description

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

Radiation curing of radical or cationic polymer sizable compounds is generally known. Special techni Radiation curing of acrylate compounds is of particular importance acquired. In the case of acrylate compounds, however, this basically exists Problem that the photopolymerization is inhibited by oxygen becomes.

Because with cationic photopolymerization the problem of the sow Material inhibition does not occur, could cationic polymeri Composable compounds are an alternative to the radical polymer risky connections. However, one is required Radically polymerizable compounds, especially the Acrylate compounds, comparable hardening speed and as good as possible application properties of coatings or moldings obtained.

In EP-A-123 912 dihydropyrans are cationically polymeric beable, cyclic vinyl ethers for radiation curing be wrote.

The curing rate, i.e. H. the reactivity in the beam hardening, but is still completely inadequate.

Dihydrofurans and their thermal, cationic polymerization are known as such, e.g. B. from Polymer Bulletin 28, 117-122 (1992).

The object of the present invention was therefore a method for Production of coatings or moldings by radiation curing, with no or hardly any oxygen inhibition occurs, the reactivity of the compounds used if possible is high and the application properties of coatings and moldings obtained are satisfactory.

Accordingly, there has been a process for making coatings or shaped bodies by radiation curing, characterized in that that radiation-curable compositions, which are from 1 to 100% by weight on the total amount of cationically and optionally polymeri sizable compounds, compounds A) with at least one cat  contain ionically polymerizable 2,3-dihydrofuran base body, be irradiated with high-energy light.

Radiation-curable compositions were also found, which are suitable for such a method are suitable.

The compounds A) are preferably compounds with 1 to 6 cationically polymerizable 2,3-dihydrofuran base bodies. The molecular weight of the compounds A) is preferably below 5000 g / mol, particularly preferably below 1000 g / mol.

Higher molecular compounds A) are especially by binding of 2,3-dihydrofuran or derivatives of polymers by polymer analog reactions possible.

Compounds A which are at least suitable are also particularly suitable contain one of the following groups:

where R 'has the following meaning: H atom, organic residue with 1 to 20 carbon atoms, in particular a C₁-C₂₀ aliphatic radical or a C₅-C₂₀ aryl, alkaryl or aralkyl radical.  

As compounds A) come with a dihydrofuran base z. B. those of formula (I)

into consideration.

The individual residues can independently have the following meaning:
R¹, R²:

(R ′ = H atom, organic radical with 1 to 20 C atoms, in particular a C₁-C₂₀ aliphatic radical or a C₅-C₂₀ aryl, alkaryl or aralkyl radical)

an aromatic or aliphatic hydrocarbon residue with 1 to 20 carbon atoms, which may be one or contain more carbonyl groups or ether groups can, optionally by one or more hydroxyl groups can be substituted or a, SiR'₃ group.

R³ H, C₁-C₂₀ alkyl or C₁-C₂₀ alkoxy
R⁴ H, C₁-C₂₀ alkyl or C₅-C₂₀ aryl, aralkyl or alkaryl radical, C₁-C₂₀ hydroxyalkyl radical,
or R³ and R⁴, or R¹ and R² together form a ring from a total of 4 to 5 carbon atoms (including ring atoms of the dihydrofuran base body), which may also contain an ether group as a constituent of the ring and optionally substituted by hydroxyl, carboxylic acid or amino groups can be.

Preferred compounds of formula I are those with

a C₁-C₂₀ hydroxyalkyl radical or a C₁-C₂₀ alkyl radical or a C₅-C₂₀ aryl radical
R³ H
R⁴ H, C₁-C₂₀ alkyl or C₁-C₂₀ hydroxyalkyl.

R¹, R³, R⁴ are particularly preferably H and R² has one of the meanings given above, in particular R² is also H or a C₁-C₂₀ alkyl radical or a phenyl radical.

The following are examples of compounds of formula I. Structural formulas listed:

As compounds A) with several 2,3-dihydrofuran basic bodies come z. B. those of the formula

where X represents a single bond or a double bond group is selected from:

which continues
R¹ to R⁴ and R 'have the meaning given above, but one of the radicals R¹ to R⁴ is omitted and X takes its place.

In the simplest case, z. B. X is a single bond, R¹, R³, R⁴ = H and R² is omitted (bond to X), so that the following structural form mel gives:

Coming as connections with several 2,3-dihydrofuran basic bodies also those of the formula

wherein R¹, R², R³, R⁴ and X have the meaning given above, each but one of the residues R¹ to R⁴ is omitted and in its place the Binding to X occurs, n is a number from 2 to 20, preferably 2 to 6, particularly preferably 2 or 3 and R₅ correspondingly one more valuable hydrocarbon residue with 1 to 20 carbon atoms, ins especially a C₁-C₂₀ alkyl radical or a C₅-C₂₀ aryl, alkaryl or Aralkyl radical, which may be ether groups or ester groups is included.  

Compounds with 2 or more 2,3-dihydrofuran bases e.g. obtainable by reaction of hydroxy-functionalized ones 2,3-dihydrofurans with polyfunctional carboxylic acids, iso cyanates, epoxides, glycidyl ethers and / or chloroformic acid esters or obtainable by reaction of carboxylic acid function lysed 2,3-dihydrofurans with polyfunctional alcohols, Amines, epoxides, glycidyl ethers and / or hydrazines.

Preferred compounds of formula III with n = 2 are

available e.g. B. by esterification of the corresponding by hydro 2,3-dihydrofurans substituted with xyl groups with dicarboxylic acids, Dicarboxylic acid esters or dicarboxylic acid chlorides,

obtainable by esterification of the corresponding by carboxyl group-substituted 2,3-dihydrofurans with diols,

obtainable by reaction of the corresponding by hydroxyl group pen substituted 2,3-dihydrofurans with diisocyanates,

obtainable by reaction of the corresponding by hydroxyl group pen substituted 2,3-dihydrofurans with chloroformic acid esters of diols,

obtainable by reaction of the corresponding by carboxyl group-substituted 2,3-dihydrofuran derivatives with diamine compound fertilize,

obtainable by reaction of the corresponding by hydroxyl group-substituted 2,3-dihydrofurans with multifunctional Glycidyl ethers.

obtainable by reaction of the corresponding by carboxyl group-substituted 2,3-dihydrofurans with multifunctional Glycidyl ethers,

with R ′ ′ ′ = R ′

obtainable by reaction of the corresponding by hydroxyl group-substituted 2,3-dihydrofurans with multifunctional Epoxies.

obtainable by reaction of the corresponding by carboxyl group-substituted 2,3-dihydrofurans with multifunctional Epoxies.  

Preferred compounds of formula III with n <2 are:

with R ′ ′ ′ ′ = H, CH₃, CH₂ CH₃

available by implementing z. B. glycerin, trimethylolethane, Trimethylolpropane with

obtainable by reacting pentaerythritol with

n = 6 esterification product of sorbitol (Chemical Abstracts Regis trier number 50-70-4) or Dipentaerythritol with

n <6 esterification product of polyvinyl alcohol with

In the above formulas II and III, the radical R 2 is preferably omitted and the bond to X takes the place of R 2.
R¹, R³ and R⁴ are preferably an H atom.
X preferably stands for

R⁵ preferably represents CH₂ _m with m = 1-6,

The synthesis of 2,3-dihydrofuran or its derivatives with n = 1 Last known to the expert and z. B. in P. Dimroth, H. Pasedach, Appl. Chemie 72, 865 (1960) or M.A. Gianturco, P. Friedel, V. Flanagan, Tetrahedron Lett., 23, 1847 (1965).

The radiation-hardness used in the method according to the invention Blen masses contain 1 to 100 wt .-%, preferably 5 to 100 be particularly preferably 10 to 100% by weight and very particularly preferably 30 to 100 wt .-%, based on the cationic and optionally Radically polymerizable compounds, the compounds A).

In particular, however, more than 50% by weight of the cationic and optionally free-radically polymerizable compounds, Compounds A), or can be in the polymerizable Connections are only connections A).  

In addition to compounds A), other cationically polymerized ones bare compounds, in particular linear or cyclic vinyl ethers, e.g. B. vinyl methyl ether, vinyl ethyl ether, vinyl propyl ether, vinyl isobutyl ether, vinyl octadecyl ether, vinyl cyclohexyl ether, and α-methyl vinyl alkyl ether into consideration.

In addition to compounds A), other cationically polymerized ones bare compounds also epoxides, for. B. cyclopentene oxide, cyclohexene oxide, epoxidized polybutadiene, epoxidized soybean oil, Dega cure K 126 or glycidyl ether, e.g. B. Butanediol diclycidyl ether, hexane diokiglycidether, e.g. B. Biphenol-A diglycidyl ether, pentaerythritol biglycidyl ether into consideration.

Cationically polymerizable can also be used Monomers such as unsaturated aldehydes and ketones, dienes such as buta dien, vinyl aromatics such as styrene, N-substituted vinyl amines such as Vinyl carbazole, cyclic ethers such as tetrahydrofuran.

In addition to cationically polymerizable compounds Radically polymerizable compounds or both radical as well as cationically polymeric compounds will. To mention are z. B. vinyl aromatics with up to 20 C-Ato men, vinyl esters of carboxylic acids with up to 20 carbon atoms and ins special (meth) acrylate compounds, such as those used for. B. with R. Holmann U.V. and E.B. Curing Formulation for Printing Inks and Points, London 1984 are described.

In addition to monoacrylates such. B. C₁-C₂₀ alkyl (meth) acrylates come especially also compounds with several (meth) acrylic groups in Consideration.

May be mentioned for. B. trimethylolpropane triacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, hexanediol diacrylate or Polyester, polyether, epoxy or urethane acrylates.

(Meth) acrylate compounds with 2 to 6, are particularly preferred preferably 2 to 4 (meth) acrylic groups. The molecular weight of the acrylate connections is preferably less than 5000, particularly preferably below 3000 g / mol.

Compounds which can be polymerized by free radicals also come into play saturated polyester into consideration.

The content of radically polymerizable compounds in the radiation-curable compositions is preferably 0 to 99, in particular preferably 0 to 70 and very particularly preferably 0 to  30 wt .-%, based on the total amount of cationic and free radicals cally polymerizable compounds.

The radiation-curable compositions preferably contain one Photoinitiator for photopolymerization.

The total amount of the photoinitiator is preferably 0.1 to 10, particularly preferably 0.5 to 5 wt .-%, based on the total amount of cationically and optionally radically polymerized connections.

Provide photoinitiators for cationic photopolymerization when irradiated with UV light acids, called its z. B. Aryldia zonium, aryliodonium or arylsulfonium salts, disulfones, diazo disulfones, imido-triflates, benzointosylates of the following structures:

Examples include p-methoxybenzene diazonium hexafluoro phosphate, benzene diazonium tetrafluoroborate, toluene diazonium tetra fluoroarsenate, diphenyliodonium hexafluoroarsenate, triphenylsulfo nium hexafluorophosphate, benzenesulfonium hexafluorophosphate, toluene olsulfonium hexafluorophosphate or Degacure K185 (bis [4-diphenyl sulfonio-phenyl] sulfide-bis-hexafluorophosphate), isoquinolinium salts, phenylpyridinium salts or picolinium salts such as e.g. B. M-ethoxy-isoquinolinium hexafluorophosphate, N-ethoxy-4-phenylpyri dinium hexafluorophosphate or N-ethoxy-2-picolinium hexafluoro called phosphate. Ferrocenium salts (e.g. Irgacure 261 from Ciba) or Titanocene are suitable.

As far as the radiation-curable compositions also radically polymeric Composable compounds contain, according to the content of these compounds also preferred photoinitiators for the radical photopolymerization also used.  

The exclusive use of photo is also possible initiators for radical polymerization, in particular if the proportion of radical-polymerizable compounds greater than 30 wt .-%, based on the total amount of polymerisable ren connections.

As photoinitiators for radical polymerization in Be traditional costumes B. benzophenone and derivatives thereof, such as. B. Alkylbenzophenones, halogen-methylated benzophenones, Michlers Ke clay as well as benzoin and benzoin ethers such as ethylbenzoin ether. Benzil ketals such as benzil dimethyl ketal, acetone phenone derivatives such. B. Hydroxy-2-methyl-1-phenylpropan-1-one and hydroxycyclohexylphenyl ketone. Anthraquinone and its derivatives such as methylanthraquinone and especially acylphosphine oxides such. B. Lucirin TPO (2,4,6-Tri methylbenzoyldiphenylphosphine oxide) and bisacylphosphine oxides.

The radiation-curable compositions are used to manufacture Be layers on the substrates to be coated, e.g. B. made of wood, Paper, plastic or metal applied or for manufacturing brought from moldings into the intended shape.

The radiation-curable compositions can be used for the respective contain conventional additives for their intended use.

When used as a coating agent, the z. B. Leveling agents, enhancers, pigments or fillers.

Radiation curing is preferably carried out with UV light. Suitable are z. B. UV lamp with a wavelength range of 240 up to 400 nm and a power of 50 to 240 W / cm.

The radiation-curable compositions are particularly preferred for the production of coatings on wood, plastic, paper, Metal, being by electron beams or after addition of Photoinitiators cross-linked by UV radiation, d. H. hardened who and coatings that meet the requirements for protection covers or decorative covers.

The radiation-curable compositions have a high reactivity, i. H. high curing speed in radiation curing.

The coatings or moldings obtained show good application properties.

Examples Example 1

2,3-Dihydrofuran and Irgacure® 261 as photoinitiators were used in Dissolved methylene chloride. The concentration of the monomer was 3 mol / l, that of the initiator 10 mmol / l. The reaction solution was at room temperature with a mercury / xenon vapor lamp radiates and then in an ammoniacal methanol solution like. The reaction proceeded with violent warming. Of the Sales were 15% after 15 seconds, complete sales was achieved in less than 120 seconds.

The polymer obtained is colorless and transparent, the average degree of polymerization P _n was 220 with a uniformity M _w / M _n of 1.8.

Example 2

Benzo (b) furan and Irgacure 261 were dissolved in methylene chloride. The concentration of the monomer was 3 mol / l, that of the initia tors 10 mmol / l. As an internal standard for gas chromatography toluene was used. The reaction solution was at room temperature irradiated with a mercury / xenon vapor lamp and turned on finally precipitated in an ammoniacal methanol solution. Of the Conversion was 76% after 5 minutes; the polymer obtained presents itself as a dark amorphous powder.

Example 3

2,3-dihydrofuran, ethyl acrylate and lucirin TPO were dissolved in toluene. The concentration of the monomers was 1.5 mol / l, that of the initiator 10 mmol / l. The reaction solution was irradiated with a mercury / xenon vapor lamp at room temperature and then precipitated in methanol. The polymer obtained is clear, colorless and of a very tough consistency. The ratio of vinyl ether to acrylate in the copolymer was 1: 3. The average degree of polymerization P _n was 23.

Comparative Example 1

3,4-Dihydro-2H-pyran and Irgacure 261 were dissolved in methylene chloride. The concentration of the monomers was 3 mol / l, that of the initiator 10 mmol / l. The reaction solution was irradiated at room temperature with a mercury / xenon vapor lamp and then precipitated in an ammoniacal methanol solution. The conversion was 9% after 5 minutes, 44% after 6.5 minutes and 93% after one hour. The polymer obtained is colorless and transparent, the average degree of polymerization P _n was 24 with a unit M _w / M _n of 1.5.

Comparative Example 2

Example 1 was repeated, but only ethyl acrylate and no cationically polymerizable compounds with were used.

Lucirin TPO was used as the initiator. As a solvent Toluene used instead of methylene chloride. The turnover was 80% after 15 minutes.

Paint samples Cationic hardening

A) A mixture of 5.5 parts of a cycloaliphatic die poxids (Degacure K126, Degussa), 2.5 parts of a polycaprolac tons (Capa 305 from Solvay Inerox, OH number 310), 2.0 parts butane diol digylcidether (Araldit DY 026 SP, Ciba Geigy) and 0.3 parts a 33% solution of bis [4- (diphenylsulfonio) phenyl] sulfide bis-hexafluorophosphate in propylene carbonate (Degacure KI 85, Degussa) is knife-coated in a layer thickness of 100 µm (wet) and with UV light (2 × 80 W / cm) at a belt speed of Irradiated 15 m / min and then post-cured at 160 ° C for 10 min.

B) as A) but with the addition of 2.0 parts of 2,3-dihydrofuran.

C) as A) but with the addition of 2.0 parts of 3,5-dihydro-2H-pyran.

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), where high values mean high hardness.

The Erichsen cupping was determined according to DIN 53156 and is a measure for flexibility, elasticity. The information is given in millimes ter (mm), whereby high values mean high flexibility.

The adhesion of the coating to substrates was determined with the Git Average test determined according to DIN 53151. Give low values good liability.

Combined radical / cationic hardening

D) 100 parts of a polyester acrylate (Laromer® Pe 55 F, BASF) are mixed with 4 parts of a photoinitiator (Irga cure 500, Ciba Geigy) mixed and under UV light (2 × 80 W / cm) irradiated at a belt speed of 6.5 m / min.

E) Analogously to D) with the addition of 20 parts of 2,3-dihydrofuran and 2 Share Degacure KI 85 (Degussa).

F) Analog B) with the addition of 20 parts of 3,5-dihydro-2H-pyran and 2 parts of Degacure KI 85 (Degussa).

Results

Approach E has the best property profile, good hardness high flexibility and very good adhesion.

Claims (10)

1. A process for the production of coatings or moldings by radiation curing, characterized in that radiation-curable compositions, which 1 to 100 wt .-%, based on the total amount of cationically and optionally radically polymerizable compounds, compounds A) with at least one cationically polymerizable 2nd , 3-Dihydrofu rangrundkörper contain, be irradiated with high-energy light. 2. The method according to claim 1, characterized in that it compounds A) are compounds with 1 to 6 cat ionically polymerizable 2,3-dihydrofuran basic bodies and a molecular weight below 1000 g / mol. 3. The method according to claim 2, characterized in that the compounds A) contain at least one of the following groups: where R 'has the following meaning: H atom, organic radical having 1-20 C atoms, in particular a C₁-C₂₀ aliphatic radical or a C₅-C₂₀ aryl, alkaryl or aralkyl radical 4. The method according to any one of claims 1 to 3, characterized records that compounds A) are 2,3-dihydro furan acts. 5. The method according to any one of claims 1 to 4, characterized records that the proportion of compounds A) 20 to 100 wt .-%, based on the total amount of cationic and optionally free-radically polymerizable compounds wearing. 6. Radiation-curable compositions containing 1 to 100 wt .-%, bezo gene on the total amount of cationic and possibly radical polymerizable compounds, compounds A) with at least one cationically polymerizable 2,3-dihy drofuran base and a photo initiator for the cat ionic and / or radical polymerization. 7. Use of radiation-curable compositions according to claim 6 for the production of coatings or moldings. 8. Compounds with two or more than two 2,3-dihydrofuran basic bodies. 9. Compounds according to claim 8, obtainable by reacting Hydroxy-functionalized 2,3-dihydrofurans with more functional carboxylic acids, isocyanates, epoxides, glycidyl ethers and / or chloroformates. 10. Compounds according to claim 8, obtainable by reacting Carboxylic acid functionalized 2,3-dihydrofurans with more functional alcohols, amines, epoxides, glycidyl ethers and / or hydrazines.