CA1042139A

CA1042139A - Photoinitiator systems

Info

Publication number: CA1042139A
Application number: CA191,375A
Authority: CA
Inventors: Anthony J. Bean; Jay K. Laufer
Original assignee: Sun Chemical Corp
Current assignee: Sun Chemical Corp
Priority date: 1973-01-31
Filing date: 1974-01-30
Publication date: 1978-11-07
Also published as: IT1006207B; JPS49110781A; FR2216304A1; DE2404156A1; GB1467645A

Abstract

ABSTRACT OF THE DISCLOSURE

The combination of a carbonyl-containing compound, an organic compound containing an element of Group V of the Periodic Table, and a halogenated hydrocarbon is effective as a photoini-tiator for the polymerization of ethylenically unsaturated compounds.
These photoinitiators are useful in printing inks, coatings, ad-hesives, pres?nsitized photopolymeric printing plates and like products for curing of monomeric or prepolymer ingredients.

Description

104;~13~

This invention relates to photopolymerization initiators.
More particularly it relates to radiation-curable compositions containing an ethylenically unsaturated monomeric compound and a photoinitiator which comprises a carbonyl-containing compound, an organic functional compound of an element of Group V of the Periodic Table, and a halogenated hydrocarbon.
The use of radiation-curable ethylenically unsaturated monomeric materials in coating compositions, printing inks, adhesives, and the like is known. It is also known that such monomeric materials are converted into polymers by the action of radiation and that they will polymerize at an improved rate when exposed to radiation in the presence of a photoinitiator.
The use of such radiation-curable compositions in inks, coatings, adhesives, and presensitized photopolymeric printing ..

104~135~
plates has been described in, for example, U.S. patents 3,551,235;
3,551,246; 3,551,311; and 3,558,387. While these products possessed good flexibility, chemical resistance, abrasion resistance, gloss, adhesion, color, and the like, it has now been found that these properties can be retained while at the same time speeding up the cure rate by incorporating in the composition a photoinitiator comprising a compound containing a carbonyl group, an organlc functional compound of an element of Group V of the Periodic Table, and if desired a halogenated hydrocarbon.
In general the composition of this invention comprise (l) at least one monomeric ethylenically unsaturated ester and (2) a photoinitiator which comprises a carbonyl-containing compound, an organic functional compound of an element of Group V, and a halogen-containing compound.
The ester (1) is a monomer or prepolymer, that is, a dimer, trimer, or other oligomer or mixture or copolymer thereof, generally described as the acrylic acid, methacrylic acid, itaconic acid, and the like, ester of an aliphatic polyhydric alcohol such as for example the di- and polyacrylates, the di- and polymeth-acrylates and the di- and polyitaconates of ethylene glycol, tri-ethytene glycol, tetraethylene glycol, tetramethylene glycol, neopentyl glycol, l,10-decane diol, trimethylolethane, trimethy-lolpropane, hutanediol, pentaerythritol, dipentaerythritol, tri-pentaerythritol, other polypentaerythritols, sorbitol, d-mannitol, diols of unsaturated fatty acids, and the like, as well as modified acrylates, methacrylates, and itaconates; acrylated, methacrylated, and itaconated prepolymers, e.g., epoxy resins, oil and oil-free alkyd resins, urethanes, linear polyesters, and so forth.
Typical compounds include, but are not limited to, trimethylol propane triacrylate, trimethylolethane triacrylate, trimethylolpro-pane trimethacrylate, trimethylolethane trimethacrylate, tetra-methylene glycol dimethacrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol diacrylate, tetraethylene glycol dimethacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol diacrylate, dipentaerythritol triacrylate, dipentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexacrylate, tripentaerythritol octoacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, dipentaerythritol dimethacrylate, dipentaerythritol tetramethacry-late, tripentaerythritol octamethacrylate, pentaerythritol diitaconate, dipentaerythritol trisitaconate, dipentaerythritol pentaitaconate, dipentaerythritol hexaitaconate, ethylene glycol dimethacrylate, 1,3-butanediol diacrylate, 1,3-butanediol dimeth-acrylate, 1,4-butanediol diitaconate, sorbitol triacrylate, sorbitol tetraacrylate, sorbitol tetramethacrylate, sorbitol pentaacrylate, sorbitol hexacrylate, modified 1,4-butylene diacry-late modified trimethylolpropane triacrylate, modified pentaery-thritol triacrylate, methacrylated epoxy resin, and the like, and mixtures and prepolymers thereof.
The photoinitiator (2) is a combination of (a) at least one compound containing a carbonyl group such as for example acyloins, such as benzoin; acyloin derivatives, such as benzoin methyl ether and benzoin ethyl ether; ketones, such as benzophenone, ace-tophenone, ethyl methyl ketone, cyclopentanone, benzil, caprone, benzoyl cyclobutanone, dioctyl acetone, and the like; substituted benzophenones, such as Michler's ketone and halogenated aceto-and benzophenones; aldehydes, such as benzaldehyde, dimethylamino-benzaldehyde, 4-hydroxy-3-methoxybenzaldehyde, 3,4-methylenedioxy-benzaldehyde, o- and p-hydroxybenzaldehydes, naphthaldehyde, and . :

.

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cinnamaldehyde; and the like;
(b) at least one organic compound of a Group V element having the formula R' - x - R"
wherein x may be nitrogen, phosphorus, arsenic, bismuth, or antimony and R, R', and R" may be alkyl, aryl, aral~yl, or alkaryl groups and may be the same or different, such as triethanolamine, diethanolamine, piperidine, p-piperidino acetophenone, n-hydroxy-ethylpiperidine, dimethylphosphine, trimethylphosphine, tributyl-phosphine, triphenylphosphine, dibutylphenylphosphine, methyldi-phenylphosphine, methylbutylphenylarsine, trioctylarsine, dibutyl-phenylbismuthine, triphenylstibene, methybutylphenylstibene, dibutylphenylstibene, and the like, and mixtures thereof; and, (c) at least one halogenated aliphatic, alicyclic, and aro-matic hydrocarbon in which the halogen may be chlorine, bromine, fluorine or idodine, such as for example polyhalogenated hydrocar-bons such as polychlorinated triphenyl and polyfluorinated phenyls, halogenated polyolefins such as chlorinated polyethylene and chlori-nated polypropylene, chlorinated rubbers such as the Parlons (Her-cules, Inc.), copolymers of vinyl chloride and vinyl isobutyl ether such as Vinoflex* MP-400 (BASF Colors and Chemicals, Inc.), chlori-nated aliphatic waxes such as Chlorowax* 70 (Diamond Alkali, Inc.), chlorinated paraffins such as Chlorafin* 40 (Hooker Chemical Co.) and Unichlor*-70B (Neville Chemical Co.), mono- and polychloro-benzenes, mono- and polybromobenzenes, mono- and polychloroxylenes, mono- and polybromoxylenes, dichloromaleic anhydride, l-(chloro-

2-methyl) naphthalene, 2,4-dimethylbenzene sulfonyl chloride, 1-bromo-3-(m-phenoxyphenoxy) benzene, 2-bromoethyl methyl ether, * Trade Mark 1()4~
chlorendic anhydride and its corresponding esters, chloromethyl-naphthyl chloride, chloromethyl naphthalene, bromomethyl phenan-threne, diiodomethyl anthracene, hexachlorocyclopentadiene, hexachlorobenzene, hexachloroparaxylene, and the like, and mixtures thereof.
The ratio of the amount of ester to the amount of initiator is about 1-lO00 to 1, and preferably about 10-50 to 1. The ratio of the amounts of the components of the photoinitiator system (a): (b):(c) is about 1-30: 1-30: 1-30, and preferably about 2-15: 2-10: 1-5.
Commonly known modifiers may be incorporated into the formu-lations using these compositions, including plasticizers; color-ants wetting agents for the colorant, such as dichloromethylstea-rate and other chlorinated fatty esters; leveling agents, such as lanolin, paraffin waxes, and natural waxes; and the like. Such modifiers are generally used in amounts ranging up to about 3 per cent by weight, preferably about 1 per cent, based on the - total weight of the formulation.
The formulations may be prepared in any known and convenient manner .
Variables which determine the rate at which a radiation-curable composition will dry include the nature of the substrate, the specific ingredients in the composition, the concentration of the photoinitiator, the thickness of the material, the nature and intensity of the radiation source and its distance from the material, the presence or absence of oxygen, and the temperature of the surrounding atmosphere. Irradiation may be accomplished by any one or a combination of a variety of methods. The composi-tion may be exposed, for example, to actinic light from any source and of any type as long as it furnishes an effect amount ' .

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of ultraviolet radiation, since the compositions activatable by actinic light generally exhibit their maximum sensitivity in the range of about 1800 ~. to 4000 A., and preferably about 2000 A.
to 3000 A.; electron beams; gamma radiation emitters; and the like; and combinations of these. Suitable sources include, but are not limited to, carbon arcs, mercury vapor arcs, pulsed xenon lamps, fluorescent lamps with special ultraviolet light-emitting phosphors, argon glow lamps, photographic flood lamps, Van der Graaff accelerators, and so forth.
The time of irradiation must be sufficient to give the ef-fective dcsage. Irradiation may be carried out at any convenient temperature, and most suitably is carried out at room temperature for practical reasons. Distances of the radiation source from the work may range from about 1 inch to 6 feet, and preferably about 5 inches to 4 feet.
When cured by radiation, the compositions of this invention are dry, flexible, abrasion resistant, and chemical resistant;
also they have excellent ink receptivity, hydrophilic-hydrophobic balance, dot resolution, and initial roll-up, making them particu-larly suitable in such applications as presensitized lithographic printing plates and photoresists. The compositions are also useful as printing inks; adhesives for foils, films, papers, fabrics, and the like; coating for metals, plastics, paper, wood, foils, textiles, glass, cardboard, box board, and the like;
markers for roads, parking lots, airfields, and similar surfaces;
and so forth.
When used as vehicles for inks, e.g., printing inks, the compositions may be pigmented with any of a variety of convention-al organic or inorganic pigments, e.g., molybdate orange, titanium white, chrome yellow, phthalocyanine blue, and carbon black, as 10~

well as colored with dyes in a conventional amount. For example, the vehicle may be used in an amount ranging from about 20 to 99.9 per cent and the amount of colorant may range from about 0.1 to 80 per cent of the weight of the total composition.
Stock which may be printed includes paper, clay-coated paper, and box board. In addition, the compositions of the present invention are suitable for the treatment of textiles, both natural and synthetic, e.g., in vehicles for textile printing inks or for specialized treatments of fabrics to produce water repellency, oil and stain resistance, crease resistance, etc.
When the radiation-curable materials of the present invention are used as adhesives, at least one of the substrates must be translucent or transparent when ultraviolet light is used. When the radiation source is an electron beam or gamma radiation, at least one of the substrates must be capable of transmitting high energy electrons or gamma radiation, respectively, and neither is necessarily translucent to light. Typical laminations include polymer-coated cellophane* to polymer-coated cellophane* films, polymer-coated cellophane* to polypropylene, Mylar* to a metal substance such as aluminum or copper, polypropylene to aluminum, and the like.
The radiation-curable compositions of the present invention may be utilized for metal coatings and particularly for metals which are to be subsequently printed. Glass and plastics may also be printed or coated, and the coatings are conventionally applied by roller or spray. Pigmented coatings systems may be used for various polyester and vinyl films; glass; polymer-coated cellophane; treated and untreated polyethylene, for example in the form of disposable cups or bottles; treated and untreated polypropylene; and the like. Examples of metals which may be coated include sized and unsized tin plate.

* Trade Mark 104~
Photopolymerizable elements prepared from the materialc of this invention comprise a support, e.g., a sheet or plate, having superimposed thereon a layer of the above-described radiation-curable material. Suitable base or support materials include metals, e.g., steel and aluminum plates; sheets; and foils; and films or plates composed of various film-forming synthetic resins or high polymers, such as addition polymers, and in particular vinyl polymers, e.g., vinyl chloride polymers; vinylidene chloride polymers; vinylidene chloride copolymers with vinyl chloride, vinyl acetate, or acrylonitrile; and vinyl chloride copolymers with vinyl acetate or acrylonitrile; linear condensation polymers such as a polyester, e.g., polyethylene terephthalate; polyamides, etc. Fillers or reinforcing agents can be present in the synthetic resin or polymer bases. In addition, highly reflective bases may be treated to absorb ultraviolet light, or a light absorbitive layer can be transposed between the base and photopoly merizable layer.
Photopolymerizable elements can be made by exposing to radiation selected portions of the photopolymerizable layer thereof until addition polymerization is completed to the desired depth in the exposed portions. The unexposed portions of the layer are then removed, e.g., by the use of solvents which dis-solve the monomer or prepolymer but not the polymer.
When used in photopolymerizable elements, the optimum dry coating thickness of the radiation-curable composition is about 0.2 to 0.4 mil. Flexibility decreases with thicker films and abrasion resistance decreases with thinner films.
When used as printing inks, coating compositions, and adhesives, the compositions as described herein are used without volatile solvents and possess many advantages over conventional _ g _ 1 O~ 3~
oleoresinous and solvent-type inks and coatings. The substrate need not be pretreated or prepared in any way. The use of volatile solvents and the attendant hazards and air pollution are eliminated. The inks and coatings have excellent adhesion to the substrate after exposure to radiation. They have good gloss and rub-resistance and withstand temperatures as high as about 150C. and as low as about -20C. The printed or coated sheets can be worked and turned immediately after exposure to the energy source.
The invention and its advantages will be better understood with reference to the following illustrative examples, but it is not intended to be limited thereto. In the examples, the parts are given by weight unless otherwise specified. Unless otherwise indicated, when the ingredient is solid at room temperature, the mixture may be heated to melt the solid ingredient, but generally not above 100C., or it may be used in a mixture with other liquid ingredients. The atmospheric and temperature conditions were ambient unless otherwise noted.
The samples were prepared as follows: 0.2 gram of the - 20 esterphotoinitiator composition was rolled onto a 2~" x 8%"
glass plate, using a "Quick-Peak" roller in order to form a uni-form film. The wet film was then transferred to a 1" x 3" glass slide which was then exposed to consecutive 0.1-second flashes of a lO0-watt/inch ultraviolet lamp until the composition was tack-free, as determined by rubbing the film with a finger.

* Trade Mark :

TABLE I .
2 Composit;on, per cent Example by weight 1 2 3 4 5 6 7 8 Pentaerythritol 00 95 95 95 95 95 95 95 5 tetraacrylate 6 Benzophenone - 5 - - 3 - 3 2 Triethanolamine - - 5 - 2 3 - 2 8 ~-6-hexachloroparaxylen~ ~ - - 5 - 2 2 g Cure speed, seconds 30 15 4.5 1.5 2.5 3.0 10 0.7 ,' ` 1 .' , ' '. ~ ' ' '" ' 16 . - . .
.. .
19' .' ',, ' ".
222~2 1 , , .

23 . ' . .
26 . . .
2~ . .
28 ~

: . ~.... ..... . -_ :., ' .-......... ... ,.,,,,, ,"~,~ ,........................ .

From these data it can be seen that the cure speed of pentaerythritol tetraacrylate with a combination of benzophenone (a conventional photoinitiator), triethanolamine (the organic compound containing a Group V element), and ~-6-hexachloropara-xylene (the halogen-containing compound) is considerably faster (Example 8) than the ester alone (Example 1) or the ester with comparable quantities of benzophenone (Example 2), of triethano-lamine (Example 3) of ~-6-hexachloroparaxylene (Example 4), and of combinations of two of these (Examples 5, 6 and 7).

The procedure of Examples 3, 5, 6 and 8 was repeated with each of the following instead of triethanolamine: dibutylphenyl-phosphine, methylbutylphenylarsine, trioctylarsine, tributyl-bismuthine, and triphenylstibine. The results were comparable.
: 15 EXAMPLES 10-16 ; 20 ~ -:

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l TABLE 11 2 Composition, per cent Example

3 by weight 10 11 1213 1415 16 _ ~ entaerythritol 94 94 9494 9494 94 s tetraacrylate 6 enzil 6 - - 3 - 3 2 7 riphenylpnosphine - 6 - 3 3 - 2 entachlorobenzene - - 6 - 3 3 2 ure speed, seconds 13 20 6 3 4 10 1.8 ~i-- . l 1~ ' '`
- 15 . .
16 .-221 . .

23 .

` 25 26 '.

29 . ` ,' 104i~
From these data it can be seen that the cure speed of pentaerythritol tetraacrylate with a combination of benzil, triphenylphosphine, and pentachlorobenzene is considerably faster (Example 16) than the ester with comparable quantities of the initiators alone (Examples 10, 11 and 12) and of combinations of two of the initiators (Examples 13, 14, and 15).
_XAMPLES 17-19 .

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l _ TABLE 111 2 Composition, per cent Example by weight 17 18 19 Pentaerythritol tetraacrylate 95 95 95 Michler's ketone 5 . - 3 6 d,c~-4-Trichloroacetophenone _ 5 2 7 . --Cure speed, seconds 9 2.5 0.9 ~ ~ , ~ ~

~2 ` - -.- ,- ----' -"' . .
.~ 16 . . - - . .

la , . .

26 . '~ .
u ~ , '.
29 . . ~ _.
jo , . .... , ., I . . I
! ,~ ~ , ... . . . . . ..
.

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l From these data it can be seen that the cure speed of 2 pentderythri tol tetraacrylate wlth a combination of Michler's 3 ketone and trichloroacetophenone (Example 19) i5 considerably ~ faster than with a comparable amount of either initiator alone ( Examples 17 and 18).

7 The procedure of Examples 1 through 19 was repeated with 8 . each of the following monomeric compounds instead of pentaerythri-9 tol tetraacrylate: pentaerythritol tr;methacrylate, 1,4-butylene o diacrylate, trimethylolpropane triacrylate, trimethylolethane ll trimethacrylate, dipentaerythritol hexacrylate, sorbitol 12 triacrylate, and sorbitol tetramethacrylate. The results were comparable. ~ . .
1, 11 ~8:~Z I

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~ . v . ' ' ' ' .
. . . . -21 . ' . .

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. 1 25 ~ ~ . .

` -27 . . .
'' 28 . . . .
29 ' . ~ I
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.:' . -16- -' ~ .. ...... I~ . .

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1()~21;~g ' 2 Composition, per cent Example 3 by ~leight2122 2324 25 26 27 ~ Trimethylolpropane 95g5 95 95 95 95 95 s triacrylate 6 Benzaldehyde S - - 3 - 3 2 7 Methyldiethanolamine - 5 - 2 3 - 2 8 resin* - - 5 - 2 2 9 Cure speed, seconds 813 10 5 8 6 2.5 ~
A *CHLOREZ 700 (Dover Chemical Co.) 12 . ` - . .
1~ . ~ .
: - 15 . . . 1., ' :-17 . : .
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29 ~ - .
30 . ' ,.

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From these data it can ~e seen that the cure speed of trimethylolpropane triacrylate with a combination of benzaldehyde, methyldiethanolamine, and a chlorinated paraffin resin is considerably faster (Example 27) than the ester with comparable S quantities of the initiators alone (Examples 21, 22, and 23) and of combinations of two of the initiators (Examples 24, 25, and 26).

An ink was prepared by grinding on a three-roll mill 85 per cent of the composition of Example 8 and 15 per cent of benzidine yellow. The ink was run on a Miehle press to print coated paper. The printed paper was exposed at a distance of 1-3/4 inches from three 21-inch 2100-watt ultraviolet lamps. The ink dried in 0.25 second and had excellent gloss and water-resistance.

The procedure of Example 28 was repeated with each of the following esters instead of pentaerythritol tetraacrylate~
pentaerythritol trimethacrylate, 1,4-butylene diacrylate, trimethylolethane triacrylate, and sorbitol tetraacrylate. The results were comparable.

The procedures of Examples 8, 16, 27, 28, and 29 were repeated except that instead of being exposed to ultraviolet light the samples were passed on a conveyor belt beneath the ; beam of a Dynacote* 300,000-volt linear electron accelerator at a speed and beam current so regulated as to produce a dose ratc ., , * Trade Mark . .

1(~ 9 l of 0.5 megarad.
2 These systems produced resinous materials of varying degrees 3 of hardness in films from 0.5 to 20 mils thick having tacky . surfaces.
s EXAMPLE 31 C The procedures of cxamples ~ , ~ , 16, ~ , 27, 7 28, and 29 were repeated except that instead of being exposed to ultraviolet light the samples were exposed to a combination of 9 ultraviolet light and electron beam radiation in a variety of arrangements: -ultraviolet light, then electron beam; electron Il beam, then ultravlolet lighti ultraviolet light before and after 12 electron beam; electron beam before and after ultraviolet radia-13 tion; and simultaneous electron beam and ultraviolet light radia-~ t;on. The re ts were comparab1e.

24 . ~ :

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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A polymerization photoinitiator comprising (a) at least one compound containing a carbonyl group, (b) at least one compound containing an element of Group V, and (c) at least one halogenated hydrocarbon, the ratio of (a):(b):(c) being about 1-30:1-30:1-30.

2. The photoinitiator of claim 1 wherein the ratio of (a):
(b):(c) is about 2-15:2-10:1-5.

3. The photoinitiator of claim 1 wherein the component (b) has the formula wherein X may be nitrogen, phosphorus, arsenic, bismuth, or antimony and R, R1, and R" may be alkyl, aryl, aralkyl, or alkaryl groups and may be the same or different.

4. In a process for photopolymerizing an ethylenically un-saturated ester by irradiating the compound in the presence of a photoinitiator, the improvement which comprises using a photoinitiator system comprising (a) at least one compound containing a carbonyl group, (b) at least one organic functional compound of an element of Group V, and (c) at least one halogenated hydrocarbon, wherein the ratio of (a):(b):(c) is 1-30:1-30:1-30 and the ratio of ethylenically unsaturated ester to photoinitiator is about 1-1000 to 1.

5. A radiation-curable composition comprising (1) at least one ethylenically unsaturated ester which is the product of the reaction of an ethylenically unsaturated acid and a polyhydric alcohol and (2) a small but effective amount of a photoinitiator system comprising (a) at least one compound containing a carbonyl group, (b) at least one compound of an element of Group V, and (c) at least one halogenated hydrocarbon wherein the ratio of (a):(b):(c) is 1-30:1-30:1-30 and the ratio of ethylenically unsaturated ester to photoini-tiator is about 1-1000 to 1.

6. The composition of claim 5 wherein the ratio of the amount of the ethylenically unsaturated compound (1) to the amount of the photoinitiator system (2) is about 10-50 to 1.