NL1006761C2 - Resin composition with improved radiation curability. - Google Patents

Description

- 1 -

RESIN COMPOSITION WITH IMPROVED 5 RADIATION CURITY

The invention relates to a radiation-curable resin composition containing at least one radiation-curable resin, a photo-excitable compound and an amine.

Such a resin composition is known from Fouassier and Rabek, Radiation Curing in Polymer Science and Technology. Full. Ill (1993), Chapter 5, biz. 153-15 176, where a radiation-curable resin composition is disclosed which contains a radiation-curable resin, a conjugated carbonyl compound, especially benzophenone as a photo-excitable compound and an ethanolamine.

The combination of a photo-excitable compound and an amine is also called a Norrish type II radical initiator combination. Such a Norrish type II combination is used to accelerate the curing of a resin under the influence of, for example, UV radiation. In such a Norrish type II combination, the photo-excitable compound reacts with the amine, also called amine synergist, to form an amine radical which subsequently initiates the polymerization reaction. In the said literature site, ethanolamines are cited as the most excellent amine synergists, it is also noted that the reaction mechanism by which the ethanolamines act is unknown. In addition to the aforementioned ethanolamines, much use is made in practice of triethylamine, which, however, exhibits a significantly worse effect than the aforementioned ethanolamines.

1006761 - 2 -

The prior art resin composition has the disadvantage that it can only be cured with a low conversion, i.e. with a maximum conversion of about 50%.

For the purposes of this invention, conversion refers to the fraction of the monomeric compounds converted to polymeric compounds upon curing.

The conversion can be determined, for example on the basis of photo-DSC measurements.

The object of the invention is to provide a radiation-curable resin composition that can be cured with a conversion that is higher than the prior art conversion.

This object is achieved according to the invention by using as the amine a compound with at least one tertiary amino group, wherein at least one substituent of the tertiary amino group is an aliphatic chain containing at least one electron withdrawing group.

This achieves that the resin composition 20 can be cured with a conversion superior or at least equal to the prior art conversion.

Surprisingly, it was also found that the resin composition of the invention could be cured at an increased cure rate that exceeds or at least equals the cure rate for the prior art resin composition.

A resin composition that can be cured with a (, increased conversion in combination with an increased cure speed is highly desirable.

For the purposes of this invention, cure speed is understood to be the ratio of the conversion (in%) over the cure time (in sec) calculated in the first linear region of the curve representing the conversion 1006761-3 versus the time of a resin composition it is cured.

The amine according to the invention is preferably a compound according to Formula 1 5 111¾¾¾ (1) wherein R1, R2 and R3 can each be chosen independently, with the proviso that at least one of the 10 substituents R1, R2 and R3 is equal to Z.

Suitable choices for R1, R2 and R3 are aliphatic and (hetero) aromatic groups, for example -alkyl groups with, for example, 1 to 100 atoms, alkenyl groups with, for example, 2 to 100 atoms and 15 (hetero) aryl groups with, for example, 6 to 100 atoms.

Aliphatic groups also include groups containing one or more atoms not equal to carbon, eg N, O, S and P. Two substituents to be selected from R1, R2 and R3 may also be part of a ring structure. It is also possible that reactive unsaturation is bound to the tertiary amine via R1, R2 and R3.

Z is an aliphatic chain containing an electron withdrawing group. The electron withdrawing group is freely selectable from the group of electron withdrawing groups, for example as stated in March, Advanced Organic Chemistry. 3th Ed. (1985) p. 238, Table 1. Examples of suitable electron withdrawing groups are nitro, cyano, carboxy, oxycarbonyl, carbamoyl, formyl, sulfo, nitroso, oxo, alkenyl and alkynyl groups. Preferably, the electron withdrawing group is a cyano, carboxy or oxycarbonyl group.

The aliphatic chain is freely selectable. Examples of suitable aliphatic chains are alkyl, 100679 "- 4 - alkenyl and alkynyl chains, for example methyl, ethyl, propyl or butyl chains. The length of the aliphatic chain is also freely selectable; however, preferably the number is carbon atoms between the electron withdrawing group 5 and the N atom on which the chain is substituted 1 to 20, more preferably 1 to 10, most preferably 1 to 5. Optionally, the aliphatic chain is also substituted, for example with (hetero) aliphatic and (hetero) aromatic groups An example of such a substituted aliphatic chain is an isobutyl chain.

Examples of suitable amines or compounds of Formula 1 are alkylamines, in which an electron withdrawing group is connected via an alkyl chain to the nitrogen atom of the tertiary amino group, for example cyanoalkylamines with an alkyl group of 1 to 5 carbon atoms, more preferably secondary or tertiary cyanoalkylamines, for example tris- (2-cyanoethyl) amine.

Preferably, the amine is a branched, highly branched or star-shaped dendrimer containing at least one tertiary amino group and in which an electron withdrawing group is linked via an alkyl chain to the nitrogen atom of the tertiary amino group. Examples of suitable dendrimers are ester-terminated polyamidoamine dendrimers, for example, described in US-A-4507466 and nitrile-terminated polypropylene imine dendrimers, for example, described in WO-A-93 14147 and WO-A-95 02008 or derivatives thereof, for example esters, wherein at least part of the end groups of the derivatives is an electron withdrawing group.

Good results were obtained with a nitrile-terminated polypropyleneimine dendrimer selected from the group consisting of: - 5 - 4 cascade: 1,4-diaminobutane [4]: propionitrile (DAB (ACN) 4), 8 cascade: 1,4-diaminobutane [4] :( 1-azabutylidene) 4: -propionittil (DAB (ACN) e), 16-cascade: 1,4-diaminobutane [4] :( 1-azabutylidene) 12: - Propionitrile (DAB (ACN) 16), 32-cascade: 1,4-diaminobutane [4] :( 1-azabutylidene) 28: -propionitrile (DAB (ACN) 32) and 64-cascade: 1,4-diaminobutane [ 4] :( 1-azabutylidene) 60: -propionitrile (DAB (ACN) 64) (for the nomenclature of 10 dendrimers, see: Newkome, J. Polymer Science. Part A: Polymer Chemistry, 31 (1993), biz. 641 -651).

Good results were also achieved with ester-terminated polypropylene imine dendrimers selected from the group consisting of the addition products of (meth) acrylates and polypropylene imine dendrimers; these addition products contain end groups that are (partially) modified with an oxycarbonyl group, for example with a methyl acrylate or ethyl acrylate group.

For example, the ester-terminated polypropyleneimine dendrimers are selected from the group of phenoxyethyl acrylate addition products and the amino-terminated polypropyleneamine dendrimers, respectively: 4-cascade: 1,4-diaminobutane [4]: propylamine (DAB (PA) 4) ), 8-cascade: 1,4-diaminobutane [4] :( 1-azabutylidene) 4: - propylamine (DAB (PA) e), 16-cascade: 1,4-diaminobutane [4] :( 1-azabutylidene ) 12: -propylamine (DAB (PA) 16), 32-cascade: 1,4-diaminobutane [4] :( 1-azabutylidene) 28: -30 propylamine (DAB (PA) 32) and 64-cascade: 1, 4-diaminobutane [4] :( 1-azabutylidene) 60: -propylamine (DAB (PA) 64).

The ester-terminated addition products are obtainable, for example, by addition of a (meth) acrylate, 1006761-6 - for example phenoxyethyl acrylate to an amino-terminated polypropylene imine dendrirer. The use of the addition products of a popypropyleneinin dendrimer and a (meth) acrylate has the additional advantage that the compatibility, for instance with regard to the solubility of the amine and the radiation-curable resin to be cured, can be easily selected by choosing of the acrylic function type.

A further advantage of polypropylene imine enders and derivatives thereof suitable as amines of the invention is that they contain a large amount of tertiary amino groups per unit weight of compound.

An additional advantage of polypropylene imine dendrimers and derivatives thereof which are suitable as amines of the invention is that the volatility of said dendrimers is lower than that of the amine synergists of the prior art. Low volatility is highly desirable because it makes it easier to work with and process the resin composition, for example for safety or environmental reasons.

For the purposes of this invention, conjugated carbonyl compound is understood to mean a compound wherein the carbonyl function is conjugated with one or more double bonds. Examples of conjugated carbonyl compounds are benzophenone, xanthone, thioxanthone, α-keto coumarin, aromatic 1,2-diketones, maleimides, acridone, pyruvates and phenylglyoxalates. Chemical derivatives of these compounds, for example, substituted benzophenones and substituted thioxanthones, are also suitable examples, as well as compounds in which more than one conjugated carbonyl compound occurs and compounds in which two or

·. . J V J I

- 7 - more carbonyl compounds are conjugated with each other.

The radiation-curable resin preferably contains a reactive unsaturation to an electron donating group (a) optionally in combination with a reactive unsaturation to an electron donating group (b) or an allyl group-containing compound to an electron donating group (c) or a mixture thereof (b + c).

The reactive unsaturation on an electron withdrawing group (a) is characterized by the structural element of Formula 2 0 R6 C ^ / ==== ^ (2) 15 Rs R4

X is one of the following groups OR7, NR7R® or SR7. R4, R5 and R6 can be chosen independently of each other; suitable choices are: H, alkyl groups with 1 to 20 carbon atoms, aryl groups, COOR9, CONR9R10, CH2COOR9, CH2OR9, OR9, NR9R10, SR9, Cl and CN. R7, R8, R9 and R10 can be chosen independently of each other; suitable choices are: H, alkyl groups of 1 to 20 carbon atoms (including linear and cyclic structures), aryl groups, 25 aromatic or aliphatic heterocyclic groups containing O, S, N or P atoms, COY, CH2COY, CH20Y, CH2NYZ, CH2SY, CH2CH2OY , CH2CH2NYZ, CH2CH2SY, CH2CH (CH3) OY, CH2CH (CH3) NYZ, CH2CH (CH3) SY, CH (CH3) CH2OY, CH (CH3) CH2NYZ, CH (CH3) CH2SY, (CH20) nY, (CHjNZ) nY , (CH2S) nY, (CH2CH20) nY, (CH2CH2NZ) nY, (CH2CH2S) nY, (CH2CH (CH3) O) nY, (CH2CH (CH3) NZ) nY, (CH2CH (CH3) S) nY, ( CH (CH3) CH2O) nY, (CH (CH3) CH2N2) nY and (CH (CH3) CH2S) nY where n is an integer, for example between 1 and 100. Y and Z are independently selectable; suitable choices are: H, alkyl groups having from 1 1006761-8 to 20 carbon atoms (including linear and cyclic structures), aryl groups and aromatic or aliphatic heterocyclic groups containing 0, S, N or P atoms.

Also derivatives of compounds with the structural element of Formula (2) are suitable choices, for example esters, anhydrides, urea, urethanes, thiourea and thiourethanes. Preferably the compound with the structural element of Formula (2) is to be chosen from the group of acrylates (X = 0R7, R4 = H, RS = H, Rfi = H), 10 methacrylates (X = OR7, R4 = CH3, RS = H, R6 = H), acrylamides (X = NR7R8, R4 = H, Rs = H, Rs = H), fumarates (X = OR7, R4 = H, Rs = COOR9, R6 = H), maleates (X = 0R7, R4 = H, R5 = H, R6 = COOR9), itaconates (X = OR7, R4 = CH2COOR9, RS = H, R6 = H), citraconates (X = OR7, R4 = CH3, Rs = H, R6 = COOR9) and mesaconates (X = OR7, R4 = CH3, R5 = COOR9, R6 = H) and derivatives thereof, for example fumaramide esters, maleamide esters and fumaramides. Cyclic structures in which X is connected to R4, R5 or R6 are also suitable examples. Examples of such cyclic structures are maleimides, for example N-20 cyclohexylmaleimide.

The reactive unsaturation to an electron donating group (b) is preferably selected from the group comprising vinyl ethers, vinyl esters, vinyl amides, vinyl amines, vinyl thioethers and vinyl thioesters.

The allyl group comprising compound to an electron donating group (c) is preferably selected from the group comprising allyl ethers, allyl ester, allylamines or allylamides.

The amount of reactive unsaturation to the electron-withdrawing group (a) of the radiation-curable resin is preferably between 25 and 100 mol%. The amount of reactive unsaturation to an electron donating group (b) or an allyl group comprising compound to an electron donating group (c) or a 1 0 0 6 "-9" mixture thereof (b + c) of the radiation-curable resin before the curing takes place, it is preferably between 0 and 75 mol%, depending on the amount of reactive unsaturation on an electron withdrawing group (a) of the radiation-curable resin.

More preferably, the amount of reactive unsaturation on an electron withdrawing group (a) of the radiation-curable resin is 100 mol%. More preferably, amount of reactive unsaturation to an electron-withdrawing group (a) of the radiation-curable resin is 50 mol% and the amount of reactive unsaturation to an electron-donating group (b) or an allyl group comprising compound to an electron-donating group (c) or a mixture thereof (b + c) of the radiation-curable resin 50-15 mol%.

The reactive unsaturation on an electron withdrawing group (a) may be linked to polymers or oligomers via R7. Examples of such polymers or oligomers are polyurethanes, polyesters, polyacrylates, polyethers, polyolefins, for example polyethylene, polypropylene, polybutadiene, polystyrene, polysilicates, polycarbonates, polyvinyl esters, rubbers, for example polyisoprene, natural rubbers and polyepoxides and mixed polymers, for example polyether urethanes, polyester surethanes. , polyether carbonates and polyepoxide esters. Also combinations of polymers or oligomers are suitable examples.

In case the reactive unsaturation on the electron withdrawing group (a) next to R7 has another functionality in the form of R4, R5 or R6, for example COOR9, CONR9R10, CH2COOR9 or CH2OR9, then the reactive unsaturation can be built into the polymeric or oligomeric chain. Examples of such polymers or oligomers are unsaturated polyesters incorporating fumarate, 1006761-10 maleate, itaconate, citraconate or mesaconate functionalities.

Preferably, the number of reactive unsaturations on an electron withdrawing group on a polymer or oligomer is greater than 1.

The reactive unsaturation to an electron donating group (b) or the allyl group-containing compound to an electron donating group (c) may be attached to the polymers or oligomers described above via ether, ester, amine or amide bonds. case of bifunctional reactive unsaturation to an electron donating group or a bifunctional allyl compound are also incorporated into a polymer or oligomeric chain.

In addition to the reactive unsaturations on or in a polymer or oligomer described above, the radiation-curable resin may also contain low molecular weight compounds with reactive unsaturation. These low molecular compounds contain a reactive unsaturation in the molecule with substituents that can be aromatic, aliphatic or cycloaliphatic in nature. Furthermore, these molecules can contain multiple functionalities, i.e. be mono and multifunctional.

Examples of radiation-curable resins that can be used are based on, for example, ethyl acrylate, ethyl methacrylate, methyl methacrylate, hexanediol diacrylate, hexanediol dimethacrylate, trimethylol propane triacrylate, trimethylolpropane-30 trimethacrylate, acrylamides, eg acrylamide, N-methyl acrylamide, acrylamide for example ethyl maleate, diethyl maleate, methyl maleate, maleamides, for example N, N'-bismaleamide, Ν, Ν'-dimethylmaleamide, maleimides, for example 1006761 - lima le imide, N-hexylmaleimide, fumarate esters, for example ethyl fumarate, fumaram itaconic acid esters, for example methylitaconate, dimethylitaconate, ethyl itaconate, itaconamides, itaconimides, citraconic acid esters, for example methylcitraconate, diethyl citraconate, mesaconic acid ester, for example methyl mesaconate, diethyl mesaconate, vinyl triethyl ether, butyl ether ether and hydroxybutyl vinyl ether, allyl compounds, for example allyl alcohol, allyl ether, diallyl ether, allylamine, diallylamine, triallylamine, allyl esters, for example acetic acid allyl ester, adipic acid diallyl ester and phthalic diallyl ester.

The resin composition can also contain additives, for example pigments, fillers and matting agents.

The amount of amine according to the invention which is used in the resin composition is freely selectable. In practice, an amount is used between 0.1 and 15% by weight and the amount inter alia depends on the solubility of the amine in the resin composition. Preferably, the amount of amine used according to the invention is 1-10% by weight, calculated relative to the total resin composition.

The amount of photo-excitable compound used is also freely selectable. In practice, an amount of between 0.1 and 15% by weight, calculated relative to the total resin composition, is used. The amount of photo-excitable compound 30 used affects the conversion and curing rate less than the amount of amine of the invention.

The radiation with which the resin composition can be cured can be selected from UV radiation, i.e. radiation with a wavelength of 0.6-380 nm and 1006761-12 electron beam (EB) radiation. The amount of radiation used depends inter alia on the curing conditions, the resin composition and the specific application and can be freely selected by the skilled person.

Amines are generally used not only to function as a synergist i.e. to initiate the reaction but also as an oxygen scavenger.

Namely, oxygen has an inhibitory effect which can be reduced by using amines. In addition to the amines according to the invention which function as a synergist and / or as an oxygen scavenger, other amines that function as a synergist and / or as an oxygen scavenger can also be added.

15 In addition to the Norrish type II already described

initiator combinations, the resin composition may also optionally contain Norrish type I initiators. In these initiators, radicals are generated by splitting a molecule under the influence of radiation.

Examples of these initiators mostly based on aromatic ketones include: Darocure 1173 <TM) (2-hydroxy-2-methyl-1-phenylpropan-1-one as active component), Irgacure 184 (TM) (hydroxy -cyclohexyl phenyl ketone as active component), Irgacure 25 369 (tm) (2-benzyl-2-dimethylamino-1- (morpholinophenyl) -butanone-1 as active component), acylphosphines such as, for example, Lucerine TPO (TM) (2.4, 6-trimethylbenzoyl-diphenylphosphine oxide).

The invention also relates to the cured resin composition obtained with the resin composition according to the invention, as well as objects made from the cured resin composition.

The invention is further illustrated by the following examples without being limited thereto.

Examples 5 Photo-DSC with inaen

The polymerization reactions were monitored by the technique. photo-DSC (Differential Scanning Calorimetry), in which heat development is monitored during a photopolymerization. The conversions and curing rates are calculated from the exotherms obtained in this way. A Perkin Elmer DSC-7 was used, equipped with an Hg lamp.

Comparative Example A

20 mg (1 wt%) dimethylethanolamine (Me2NEtO) and 20 mg (1 wt%) benzophenone were dissolved in 1.96 g phenoxyethyl acrylate. 11.9 mg of this solution was transferred to a DSC pan and cured in the photo DSC using UV light. The 20 results of this are shown in Tables 1 and 2.

Comparative Example B

20 mg (1 wt%) triethylamine (Et3N) and 20 mg (1 wt%) benzophenone were dissolved in 1.96 g phenoxyethyl acrylate. 11.9 mg of this solution was transferred to a DSC pan and cured in the photo DSC using UV light. The results are shown in Tables 1 and 2.

Example I: nitrile-terminated polvoroprene imine dendrimer DAB (ACN) λ 20 mg (1 wt%) nitrile-terminated polypropylene imine dendrimer DAB (ACN) 4 (DSM Astramol®, 1006761 - 14 - generation 0.5) and 20 mg (1 wt%) benzophenone was dissolved in 1.96 g of phenoxyethyl acrylate. 12.3 mg of this solution was transferred to a DSC pan and cured in the photo DSC using UV light. The 5 results of this are shown in Table 1.

The polypropylene imine dendrimers were purchased from DSM N.V. (Heerlen, the Netherlands)

Examples II-III: 10 nitrile-identified polypropylene imine dendrimers

Example I was repeated with 20 mg (1 wt%) of the nitrile-terminated polypropylene imine dendrimers DAB (ACN) 3 and DAB (ACN) 16 (DSM Astramol®, generations 1.5 and 2.5). The results are shown in Table 1. The 15 dendrimers DAB (ACN) 4, DAB (ACN) e and DAB (ACN) 16 give a conversion superior to that according to Comparative Examples A and B while the cure speed is superior or comparable to those according to Comparative Examples A and B.

1006T61 - 15 -

Pre-Amine Conversion Curing Image (%) Rate (% / min) A Me2NEtO 53 16.8 B Et3N 18 5.4 5 I DAB (ACN) 4 80 22.2 II DAB (ACN) 8 70 14.2 III DAB (ACN) 16 56 11.4

Table 1: Conversions and cure rates for 10 different amines.

Example IV: Phenoxylated Flavate Plate Terminated Polypropylene Imine Dendrimer 20 mg (1 wt%) Amino Terminated Polypropylene Imine Dendrimer DAB (PA) 4 (DSM Astramol®, Generation 1) and 20 mg (1 wt%) Benzophenone Dissolved 96 g of phenoxyethyl acrylate. The clear solution was stirred for a week. 11.9 mg of the solution of the phenoxyethyl acrylate-modified dendrimer DAB (acrylate) 4 formed was transferred to a DSC pan and cured in the photo-DSC using UV light. The results are shown in Table 2.

Example V-VIII; fenoxyl ether plate-terminated polypropylene imine dendrimers

Example IV was repeated with 20 mg (1 wt%) of the amino-terminated polypropylene imine dendrimers DAB (PA) 8, DAB (PA) 16, DAB (PA) 32 and DAB (PA) 64 1006761 - 16 - (DSM Astramol ®, generation 2, 3, 4 and 5). The results are shown in Table 2. All modified dendrimers tested give a conversion higher than the conversion achieved according to Comparative 5 Examples A and B. All dendrimers also give a cure speed superior or comparable to that according to Comparative Example A and B.

Pre-Amine Conversion Curing 10 Image (%) Rate (% / min) A Me2NEtO 53 16.8 B Et3N 18 5.4 IV DAB (Acrylic) 4 83 21.1 V DAB (Acrylic) 8 71 19.4 15 VI DAB (acrylic) 16 62 15.3 VII DAB (acrylic) 32 62 12.3 VIII DAB (acrylic) i4 62 12.2

Table 2: Conversions and cure rates for 20 different amines. DAB (acrylate) x = reaction product of DAB (PA) x and phenoxyethyl acrylate.

Examples IX-XV;

Effect of Amine Amount Example I was repeated with varying amounts of amine (0.1 to 10%). The results of this are shown in Table 3. This shows that with an approximately constant and high conversion a curing speed can be achieved which increases with the ^ 0 U o? j: j - 17 - amount of amine.

Pre-Concentration Conversion Curing image (weight%) (%) speed (% / min) 5 IX 0.1 79 18.1 X 0.2 79 18.3 XI 0.4 85 22.3 XII 1 86 27, 6 XIII 2 84 34.0 10 XIV 4 84 46.5 XV 10 (*) 82 44.6

Table 3: Effect of the concentration of the amine DAB (ACN) 4 in the resin composition.

* At this concentration, a fraction of the amine no longer dissolved in the reaction mixture.

1006761

Claims (12)

Radiation-curable resin composition containing at least one radiation-curable resin, a photo-excitable compound and an amine, characterized in that the amine is a compound having at least one tertiary amino group, at least one substituent of the tertiary amino group being aliphatic chain containing at least one electron withdrawing group. Radiation-curable resin composition according to claim 1, characterized in that as amine a compound of Formula 1 is selected RxR2R3N (1) wherein: R1, R2 and R3 are each independently selectable, with the proviso that at least one of the substituents R1, R2 and R3 is Z; Z is an aliphatic chain containing an electron withdrawing group. Radiation curable resin composition according to any one of claims 1-2, characterized in that the electron withdrawing group is a cyano, carboxy or oxycarbonyl group. Radiation-curable resin composition according to any one of claims 1 to 3, characterized in that the number of carbon atoms between the electron withdrawing group and the N atom on which the chain is substituted is preferably 1 to 20, more preferably 1 to 10, with the most preferred is 1 to 5. Radiation-curable resin composition according to any one of claims 1 to 4, characterized in that the amine 1006761-19 is an alkylamine in which an electron withdrawing group is linked via an alkyl chain to the nitrogen atom of a tertiary amino group. Radiation-curable resin composition according to any one of claims 1 to 4, characterized in that the amine is a branched, highly branched or star-shaped dendrimer containing at least one tertiary amino group and in which an electron withdrawing group is connected via an alkyl chain to the nitrogen atom of the tertiary 10 amino group. Radiation curable resin composition according to claim 6, characterized in that the dendrimer is a polypropylene imine dendrimer. Radiation-curable resin composition according to claim 7, characterized in that the polypropylene imine dendrimer is selected from the group consisting of DAB (ACN) 4, DAB (ACN) e, DAB (ACN) 1S, DAB (ACN) 3 2, DAB (ACN) 64 and the addition products of amino-terminated polypropylene imine dendrimers and 20 (meth) acrylates. Radiation-curable resin composition according to any one of claims 1-9, characterized in that the amount of amine used is 1-10% by weight, calculated relative to the total resin composition. Cured resin composition obtained with the resin composition according to any one of claims 1-9. Object made from the cured resin composition according to claim 10. 12. Resin composition, as described and illustrated by the examples. 100676 "