EP0852593A1

EP0852593A1 - Acrylated polyether polyol and the use thereof for radiation-curable formulations

Info

Publication number: EP0852593A1
Application number: EP96933395A
Authority: EP
Inventors: Wolfgang Kranig; Martin Lobert
Original assignee: BASF Coatings GmbH
Current assignee: BASF Coatings GmbH
Priority date: 1995-09-27
Filing date: 1996-09-26
Publication date: 1998-07-15
Also published as: WO1997011982A1; DE19535936A1; US6090866A; JPH11512757A

Abstract

The invention relates to an acrylated polyether polyol which consists of an ethoxylated polyol with a molecular weight of from 600 to 1000, preferably 700 to 900, esterified with acrylic acid.

Description

Acrylated polyether polyol and its use for radiation-curable formulations

The present invention relates to a novel acrylated polyether polyol which can be used in particular for radiation-curable coating compositions.

It is known to harden compositions based on acrylic acid esters by radiation, in particular UV radiation. Here, however, the problem arises that the presence of air interferes with the curing, in particular of surfaces.

From DE-PS 2625538 photopolymerizable coating compositions are known which contain amines as reducing agents or chain-transferring compounds. The use of such a free amine has the disadvantage that it can act as a plasticizer and leads to an undesirable coating on the surface.

By incorporating the amino group into a molecule which still contains groups capable of polymerization, a copolymerized amine is obtained which does not have the disadvantages mentioned above. A known method of incorporation is the addition of amines to molecules rich in double bonds, which proceeds analogously to a Michael addition and is described, for example, in F. Möller, Houben-Weyl, Vol. 11/1 (1957), pp. 277-280. US Pat. No. 2,759,913 teaches the addition of amines to activated, olefinically unsaturated compounds, such as acrylates, in equimolar amounts, which leads to the complete conversion of the activated ethylenic double bonds. Systematic studies on the attachment of amino alcohols to acrylates were carried out by Ogata. Bull. Chem. Soc. Jap. 39 pages 1486-1490. 1966.

DE-PS 2 346 424 describes the preparation of radiation-curable compositions, starting from acrylic esters of polyhydric alcohols and secondary, aliphatic monofunctional amines.

These masses have the disadvantage of reduced storage stability.

The addition of a secondary amine also leads to one

Reduction of the acrylic ester functionality of the molecule and thus also reduction of the crosslinking possibilities for the radiation-induced polymerization.

From EP application 0280222 addition products of acrylic acid esters and a polyhydric alcohol with a primary monoamine are known, which are used for radiation-curable coating compositions.

Also known from EP-PS 0586849 are amino acrylates with a viscosity of 2000 to 3000 mPas, a content of olefinic double bonds of 8 to 20% by weight and a nitrogen content of 0.4 to 2.0% by weight Binders can be used for radiation-curable coating compositions. The disadvantage of the products mentioned is the tendency to yellowing, in particular of the amine-modified polyether acrylates.

The object of the present invention is to provide an acrylated polyether polyol which can be used in radiation-curable coating formulations and which does not have the disadvantages mentioned above.

This object is achieved in that the acrylated polyether polyol consists of an ethoxylated polyol with a molecular weight of 500 to 1000, preferably 700 to 900, esterified with acrylic acid.

In a preferred embodiment, the polyether acrylate according to the invention consists of 50 to 75% by weight, preferably 55 to 65% by weight of a polyether polyol, 20 to 50% by weight, preferably 30 to 45% by weight of acrylic acid and 5% by weight. % usual auxiliary substances.

The ether alcohols used generally have a degree of ethoxylation of from 10 to 20, preferably from 13 to 17, the degree of ethoxylation indicating the number of moles of ethylene oxide which have been added on average to 1 mole of an alcohol used as starter molecule. Ethoxylated trihydric or tetravalent alcohols with a degree of ethoxylation of 3 to 6 and a molecular weight of 224 to 400 are particularly preferably used. Ethoxylated erythritol with a molecular weight of 500 to 1000, preferably 700 to 900, is preferably used. One example is pentaerythritol etherified with 15 ethoxy units. They are preferably polyether polyols with an OHN of 150 to 350 mg KOH / g, preferably 250 to 320 and a viscosity of 300 to 1000, preferably 400 to 600 mPas.

The hydroxyl group-containing polyethers which are esterified with acrylic acid and / or methacrylic acid are obtained by reacting the di- and / or polyhydric alcohols with different amounts of ethylene oxide using well-known methods (cf., for example, Houben-Weyl, Vol. XIV, 2. Macromolecular Substances II, (1963) obtained.

Alcohols containing ether groups are essentially free of -CH ₂ -CH (CH ₃ ) -0- propylene oxide units. This means that in addition to ethylene oxide, minor amounts of propylene oxide are used in the alkoxylation reaction (molar ratio of ethylene oxide to propylene oxide at least 5: 1).

The present invention also relates to a method for producing an acrylated polyether polyol which is suitable for use in particular in radiation-curable formulations. In this process, polyether polyol and acrylic acid are first heated to 70 to 110 ° C, preferably 80 to 100 ° C in the presence of an entrainer. Only substances whose boiling point is between 60 and 110 ° C., preferably between 70 and 90 ° C., are suitable as entraining agents. This temperature is maintained until the acid number falls below 60 to 80, preferably 65 to 75. The proportions of the polyether polyol are usually 50 to 75% by weight, preferably 55 to 65% by weight. The acrylic acid is added in amounts of 20 to 60% by weight, preferably 30 to 45% by weight. In addition, the Mixture of polymerization inhibitors, for example hydroquinones, catalysts to accelerate the esterification reaction and antioxidants.

As soon as the acid number has reached the desired value, acrylic acid is again added in an amount of 1.5 to 5, preferably 2 to 3,% by weight until the acid number has dropped below 40, preferably below 35. A vacuum is then applied until the acid number has fallen below 20, preferably below 15, and a viscosity of 1 to 8, preferably 2 to 6, particularly preferably 3 to 4.5 mPas has been established. The reaction is continued until the acid number has dropped below 40, preferably below 35.

The acrylated polyether polyol thus produced now still contains residual acrylic acid and entrainer, which are removed together in vacuo at temperatures from 110 to 130 ° C.

The acrylated polyether polyol according to the invention is particularly suitable for radiation-curable coating compositions. These can e.g. from 40 to 90% by weight, preferably 50 to 60% by weight urethane acrylate, 0 to 20% by weight, preferably 10 to 15% by weight polyether acrylate, 10 to 50% by weight, preferably 25 to 40% by weight % Reactive diluent, 0 to 10% by weight, preferably 3 to 6% by weight photoinitiator, 0 to 30% by weight pigments and 0 to 10% by weight of other fillers customary in lacquer.

The urethane acrylates here preferably consist of 30 to 45% by weight of polyester, very particularly preferably 30 to 40% by weight, 0.01 to 0.1% by weight of catalysts, 0.05 to 0.1% by weight of stabilizers, 10 to 20, preferably 15 to 20% by weight of hydroxyethyl acrylate, 15 to 25, preferably 15 to 20% by weight of reactive diluent and 20 to 35, preferably 25 to 35% by weight of a diisocyanate component.

The polyesters used consist of 50 to 75% by weight, preferably 55 to 65% by weight of alcohol and 20 to 50, preferably 30 to 45% by weight of acid and 5% by weight of customary auxiliaries.

The hydroxyl-containing polyester resins are prepared in a known manner by esterification of polyvalent carboxylic acids with polyhydric alcohols in the presence of suitable catalysts. Instead of the free acid, its ester-forming derivatives can also be used. Alcohols suitable for the preparation of the polyesters are, for example, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol and diethylene glycol , Triethylene glycol and triols, such as Glycerin, trimethylolethane, trimethylolpropane and tris-2-hydroxyethyl isocyanurate.

Cycloaliphatic alcohols such as cyclohexanols and 1,4-bis (hydroxymethyl) cyclohexane, aromatic alcohols such as 1,3-xylylenediol and phenols such as 2,2-bis (4-hydroxyphenyl) propane (bisphenol A) can also be used .

Mixtures of trimethylolpropane, triethylene glycol and cyclohexanedimethanol are preferably used. Also suitable are dihydric aliphatic alcohols, such as 1,4-hexanediol, 1,6, 2-methylpentanediol, 5, 2-ethylbutanediol, 4, dimethylolcyclohexane, trihydric alcohols, such as trimethylolbutane, tetravalent alcohols, such as pentaerythritol, as well as higher alcohols such as di- (trimethylolpropane), di- (pentaerythritol) and sorbitol.

Suitable carboxylic acids are, for example, phthalic acid, isophthalic acid, terephthalic acid and their esterifiable derivatives, such as e.g. the anhydrides, if they exist, and the lower alkyl esters of the acids mentioned, e.g. Methyl, ethyl, propyl, butyl, amyl, hexyl and octyl phthalates, terephthalates and isophthalates. Both the half esters, the dialkyl esters and mixtures of these compounds can be used. The corresponding acid halides of these compounds can also be used. Mixtures of phthalic anhydride, isophthalic acid and adipic acid are preferred.

Suitable for the production of the urethane acrylate are aliphatic and / or cycloaliphatic diisocyanates, such as e.g. 1,3-cyclopentane, 1,4-cyclohexane, 1,2-cyclohexane diisocyanate, 4,4'-methylene bis (cyclohexyl isocyanate) and isophorone diisocyanate, trimethylene, tetra methylene, pentamethylene, hexamethylene and trimethylhexamethylene 1, 6-diisocyanate and the diisocyanates derived from dimer fatty acids described in EP-A-204 161, column 4, lines 42 to 49. Isophorone diisocyanate is preferably added to the hydroxy-functional polyester.

By adding hydroxyl group-containing acrylic esters or methacrylic esters, such as hydroxyethyl acrylate or hydroxybutyl acrylate The monomers or oligomers containing isocyanate groups are obtained in the polyurethane acrylates or methacrylates. So that no undesired polymerization takes place in the addition reaction, the reaction mixture is generally added to the reaction inhibitors as stabilizers. Suitable polymerization inhibitors include known products, such as substituted phenols, such as 2,6-di-tert-butyl-p.cresol, hydroquinones, such as methyl hydroquinones, and thiol ethers, such as thiodiglycol or phenothiazine.

Depending on the viscosity of the ester reaction diluents, the radiation-curable coating compositions may preferably contain known copolymerizable compounds, for example for use in radiation-curable coating compositions. (Meth) acrylic acid esters, especially methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isopropyl (meth) acrylate, pentyl (meth) acrylate, isoamyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, 3,5,5-

Trimethylhexyl (meth) acrylate, decyl (meth) acrylate ,. Hexadecyl (meth) acrylate, octadecyl (meth) accrylate,

Octadecenyl (meth) acrylate, phenoxyethyl acrylate and the corresponding esters of maleic, fumaric, tetrahydrophthalic, crotonic, isocrotonic, vinyl acetic and itaconic acid. Monomers with more than one double bond per moiety, e.g. Ethylene glycol diacrylate, diethylene glycol diacrylate, propylene glycol diacrylate, trimethylene glycol diacrylate, neopentyl glycol diacrylate, 1.3

Butylanglycoldiacrylat, 1,4-Butylenglycoldiacrylat, 1,6-

Hexamethylene glycol diacrylate, 1, 10 decamethylene glycol diacrylate, Trimethylolpropane triacrylate, pentaerythritol tetraacrylate and

Pentaerythite tetraacrylate and the corresponding methacrylates. Also suitable are the ethoxylated or propoxylated derivatives and the long-chain linear diacrylates described in EP-A-250631 with a molecular weight of 400 to 4000, preferably 600 to 2500. 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. Isobornyl acrylate, trimethylolpropane triacrylate and acrylic acid esters of ethoxylated pentaerythritol are very particularly preferably used.

The addition of this ethylenically unsaturated compound controls the viscosity and the rate of curing of the coating compositions and the mechanical properties of the resulting coating, 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 .

The photoinitiator usually used in the coating compositions in an amount of 0 to 10% by weight, preferably 3 to 6% by weight, based on the total weight of the coating compositions, varies with the radiation used to harden the coating compositions (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, Diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one,

Hydroxypropylphenyl ketone, m-chloroacetophenone, propiophenone, benzoin, benzil, benzil dimethyl ketal, anthraquinone, thioxanthone and thioxanthone derivatives and triphenylphosphine and others. as well as mixtures of different photoinitiators.

In addition, the coating compositions may also contain pigments and customary lacquer fillers, customary auxiliaries and additives. The former are used in amounts of 0 to 30% by weight. The proportion of fillers customary in paint is 0 to 10% by weight. Auxiliaries and additives 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, plasticizers (e.g. extenders, such as talc, heavy spar, aluminum silicate, dolomite, defoamers and film-forming aids, e.g. cellulose derivatives, matting agents in customary amounts) and, in particular, adhesion promoters. Alkoxysilanes, such as N-β-aminoethyl,

Aminopropyltrimethoxysilane, -aminopropyltrimethoxysilane, N-methyl-ß-aminopropyltrimethoxysilane or triamine-modified

Propyltrimethoxysilane (eg adhesion promoter DYNASLYAN ^R , 'type TRIAMO ", commercial product from Dynamit Nobel Chemie) is used.

0 to 10, preferably 2 to 5% by weight of a carboxy-functional (meth) acrylic acid ester can be used as additional adhesion promoter. Examples are ß-carboxyethyl acrylate and EBECRYL 169 or 170 available from UCB, SA, Drogenbos, Belgium. The coating films are cured by means of radiation, preferably by means of electron beams. The facilities 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 Kingdom 1984) and do not require any further description .

The lacquer films harden immediately after application or after the water present has evaporated by means of UV or electron beams. The facilities 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 Kingdom 1984, pages 79-111 ) and need no further description.

The use of the acrylated polyether polyol according to the invention leads, in particular in the coating formulations described based on urethane acrylate, to properties which have hitherto not been achieved with other formulations. In particular, tensile strength and elongation at break can be controlled over a wide range without the other paint film properties (reactivity, chemical resistance,

Surface quality) significantly. The acrylated polyether polyol can be water-thinned up to 50% homogeneously and thus enables sprayable water-based paints that can be hardened with electron beams or UV rays after the water has evaporated. The values determined so far here show a significant improvement compared to binders customary in the market up to now. The invention is described in more detail below with reference to the examples:

A. Preparation of the polyether acrylate

64.9 2 parts of polyether polyol, 23.519 parts by weight of acrylic acid, 0.547 parts by weight of p-toluenesulfonic acid, 0.180 parts by weight of hydroquinone, 0.180 parts by weight of hypophosphorous acid and 8 parts by weight of cyclohexane are weighed in and heated to 85.degree. This temperature is maintained until the acid number of the reaction mixture falls below 70. 2.352 parts by weight of acrylic acid and 0.3 part by weight of cyclohexane are then added and the reaction is continued until the acid number drops below 35. A vacuum is then applied and maintained until the acid number has dropped below 8 and the viscosity is 2.5 to 3.5 mPas sec. is.

B. Preparation of the urethane acrylate

1st stage: A polyester with an OH number of approximately 210 is produced by weighing 6.40 parts by weight of trimethylolpropane, 19.787 triglycol, 33.381 parts by weight of cyclohexane dimethanol, 13.007 parts by weight of phthalic anhydride, 14.588 parts by weight of isophthalic acid and 12.831 parts by weight of adipic acid. A condensation reaction is carried out at 240 ° C until the following key figures are reached:

Acid number 3 to 5

Viscosity 3.5 to 5.0 mPas

Plate-cone viscosity at 23 ° C 70% in methoxypropanol 2nd stage: 34.139 parts by weight of the polyester produced in stage 1 are weighed together with 0.039 dibutylzindilaurate, 0.078 part by weight of di-tert-butyl-p-cresol, 15 parts by weight of hydroxyethyl acrylate, 21.956 parts by weight of phenoxyethyl acrylate, 30 ppm of phenothiazine and heated to 60 ° C. . 28.707 ppm isophorone diisocyanate and 0.080 ppm ethanol are metered in so that the temperature remains below 65 ° C. It is kept at 60 ° C until the NCO content falls below 1.5%. The mixture is then heated to 90 ° C. until the NCO content has dropped below 0.1%.

C. Examples of varnishes

Example 1: Free paint film

39.8 parts aromatic urethane acrylate, 80% in phenoxyethyl acrylate, 20 parts acrylated polyether polyol, 14.8 parts isobornyl acrylate, 24.8 parts titanium dioxide, 0.3 parts emulsifier (Tween 80), 0.3 parts dispersing aid.

Example 2: Free paint film

39.8 parts aromatic urethane acrylate, 80% in phenoxyethyl acrylate, 10 parts acrylated polyether polyol, 14.8 parts isobornyl acrylate, 10 parts ethoxylated pentaerythritol tetracrylate SR 494 (Cray Valley) 24.8 parts titanium dioxide, 0.3 parts emulsifier (Tween 80), 0.3 parts of dispersing aid.

Example 3: Free paint film 39.8 parts aromatic urethane acrylate, 80% in phenoxyethyl acrylate, 1.0 part acrylated polyether polyol, 14.8 parts isobornyl acrylate, 19.0 parts ethoxylated pentaerythritol ethacrylate SR 494 (Cray Valley) 24.8 parts titanium dioxide, 0.3 part emulsifier ( Tween 80), 0.3 part of dispersing aid.

The components are weighed into the containers customary in paint technology and mixed with a dissolver.

Mechanical properties of the paints according to Examples 1 to 3

Example tensile strength (N / mm ² ) elongation at break (%)

1 10 24 2 15 15

3 25 9

The tensile strength and elongation at break can be controlled in a wide range with the described acrylated polyether polyol without significantly influencing the other paint film properties (reactivity, chemical resistance, surface smoothness).

Example 4: Spray paint

50 parts of acrylated polyether polyol, 48 parts of water, 2 parts of Irgacure 500 (photoinitiator, Ciba Geigy) The varnish has good sprayability at room temperature as well as an excellent pore pattern on wood or veneer.

Example 5: Clear varnish

96 parts of acrylated polether polyol, 4 parts of I. 500

The paint has excellent weathering stability.

Claims

claims

1. Acrylated polyether polyol, characterized in that it consists of an ethoxylated polyol having a molecular weight of 600 to 1000, preferably 700 to 900, esterified with acrylic acid.

2. Acrylated polyether polyol, characterized in that the polyol has an OH number of 150 to 350, preferably 250 to 320 mgKOH / g and a viscosity of 300 to 1000, preferably 400 to 600 mPas.

3. Acrylated polyether polyol according to one of claims 1 or 2, characterized in that the polyol is 10 to 20, preferably 13 to 17 times ethoxylated.

4. Acrylated Polyetheφolyol according to any one of claims 1 to 3, characterized in that the polyether acrylate consists of 50 to 75 wt .-% polyether polyol, 20 to 50 wt .-% acrylic acid and 0 to 5 wt .-% of conventional auxiliaries.

5. Acrylated Polyetheφolyol according to any one of claims 1 to 4, characterized in that the polyether acrylate consists of 55 to 65 wt .-% polyether polyol and 20 to 50 wt .-% acrylic acid.

6. Acrylated polyether polyol, characterized in that it consists of ethoxylated pentaerythritol.

7. Acrylated Polyetheφolyol according to any one of claims 1 to 6, characterized in that it is modified with amines, preferably ethanolamine, dimethylaminopropylamine.

8. Acrylated polyether polyol, characterized in that it contains UV initiators, preferably benzophenone.

9. A process for the preparation of an acrylated polyether polyol, characterized in that polyether polyol and acrylic acid are heated to 70 to 110 ° C, preferably 80 to 100 ° C, this temperature is maintained until the acid number has dropped below 60 to 80, preferably 65 to 75 then acrylic acid is added until the acid number has dropped below 40, preferably below 35, then a vacuum is applied until the acid number has dropped below 20, preferably below 15 and a viscosity of 1 to 8, preferably 2 to 6, has particularly preferably set 3 to 4.5 mPas.

10. Use of the acrylated polyether polyol according to one of claims 1 to 8 for radiation-curable coating composition.