US3827960A - Process for photopolymerization with carbonylated polynuclear sulfonyl chloride sensitizers - Google Patents

Abstract

U.V. POLYMERIZATION OF A PHOTOPOLYMERIZABLE VEHICLE IS IMPROVED BY INCORPORATING INTO THE VEHICLE ABOUT 0.5%% BY WEIGHT OF A CARBONYLATED POLYNUCLEAR SULFONYL CHLORIDE.

Description

3,827,960 PROCESS FOR PHOTOPOLYMERIZATION WITH CARBONYLATED POLYNUCLEAR SULFONYL CHLORIDE SENSITIZERS Vincent Daniel McGinniss, Middleburgh Heights, Ohio, assignor to SCM Corporation, Cleveland, Ohio No Drawing. Filed Jan, 12, 1973, Ser. No. 323,086 Int. Cl. C08d 1/00; C08f 1/16 U.S. Cl. 204-15914 7 Claims ABSTRACT OF THE DISCLOSURE U.V. polymerization of a photopolymerizable vehicle is improved by incorporating into the vehicle about 0.5- by weight of a carbonylated polynuclear sulfonyl I chloride.

CROSS-REFERENCE TO RELATED APPLICATION The present patent application is related to my copending patent application bearing the identical title, and having the identical filing date, i.e., Jan. 12, 1973, and identified with Ser. No. 323,032.

BACKGROUND OF THE INVENTION This invention relates to an improvement in process for polymerizing (curing) a photopolymerizable vehicle by exposure of same to U.V. radiation. Curing herein connotes polymerization and hardening to obtain a product that is practical for ordinary use and normally is tackfree.

The vehicle used herein is the binder for a film in the nature of a paint, varnish, enamel, lacquer, stain, filler or ink. The polymerized product can be a clear one, optionally tinted, or an opaque one, both in a variety of colors for the purpose of protecting, decorating, and/or applying a message on a substrate. For convenience herein the binding vehicle alone for polymerization and such vehicle compounded with other ingredients Will be referred to from time to time herein as a paint. This paint can be a fluent, liquid phase-continuous material or a powdery mixture. It can have, if desired, opacifying pigment, added colorants and fillers, in conjunction with such binding vehicle. Such paint also can have various other conventional additives such as pesticides, odorants, flow-control agents, bubble breakers, defoamers, plasticizers, intercoat adhesion-promoters, and other ingredients conventional in surface coating films.

Conventional convection ovens and infrared sources have been used to cure (polymerize) binders in surface coating or decorating films and inks, often with the assistance of a catalyst in such deposit. More recently ultraviolet (U.V.) wave energy curing of such binders (vehicles) has been suggested using suitable U.V. sensitizers for initiating photopolymerization at wave lengths in the U.V. spectrum that are transmittable through a quartz or other transparent window, generally such range understood as lying between about 1600 A. and about 4000 A.

Typical U.V. emitters for such curing include ones such as the plasma arc torch described in U.S. Pat. 3,3 64,3 87, various electric arc lamps, and even lasers having a lasing output in the U.V. spectrum range (as shown in the copending U.S. patent application of De Souza and Buhoveckey, U.S. Ser. No. 189,254). The subject matter of that application and U.S. Pat. 3,364,387 are incorporated herein by reference.

Advantages of the instant invention over prior proposals include especially economical and efiicient utilization of U.V. energy, particularly that in wave lengths between about 3200 A. and 4000 A. to perform cold polymerization (curing) of the vehicle at quite high speed with attendant suppression of losses due to volatilization United States Patent 0" Patented Aug. 6, 1974 of components of paint,"suppression of discoloration or degradation of the resulting deposit (which can be generally considered a film) and avoidance of shrinkage and distortion (the preservation of dimensional stability) and suppression of degradation of the substrate to which the vehicle deposited is applied, particularly when such substrate is a plastic, or paper, or fabric.

SUMMARY OF THE INVENTION wherein R represents hydrogen, alkyl (C a-haloalkyl (C phenyl and substituted phenyl wherein the substituent is alkyl, alkoxy, a-haloalkyl or chlorosulfonyl, polynuclear aromatic radical; and R and R represent one or more fused ring, alkyl (C and a-haloalkyl; and n is a number of at least 1.

Typical sulfonyl chloride compounds are:

l-Chloromethyl, 6-chlorosulfonyl naphthyl-Z, phenyl ketone.

6-Chlorosulfonyl naphthyl-l, phenyl ketone.

8-chloromethyl S-Chlorosulfonyl,

naphthyl-2, phenyl ketone.

CHzCl SOzCl l-Chlorosulfonyl anthracyl-9, phenyl ketone.

Z-Chloiosulfonyl anthracyl-9-,- phenyl ketone.

6-chlorosulfonyl l-chlororneth'yl,

naphthyl-Z, hexyl ketone.

moor o S-Chlorosulfonyl, naphthyl-2, a-bromopentyl ketone.

S0201 4-methoxy, S-chlorosulfonyl naphthyl-Z, methyl ketone.

O iil--CH clots ot'zm 6-Chlorosulfonyl phenanthryl-Z phenyl ketone.

7-Chlorosulfonyl phenanthryl-Z phenyl ketone.

8-Chlorosulfonyl phenanthryl-Z phenyl ketone.

Z-Chlorosulfonyl phenanthryl-3 phenyl ketone.

6-Chlorosulfonyl phenanthryl-3 phenyl ketone.

8-Chlorosulfonyl phenanthryl-3 phenyl ketone.

3-Chlorosulfonyl, S-benzoyl acenaphthene.

SOrCl Monochlorosulfonation of such compounds appears adequate, and thus is preferred for efficiency and econo'rny. There appears to be no particular significance attributed to the position of the sulfonyl chloride radical in relation to the carbonyl group. The essential feature is that the sul-fonyl chloride be substituted on the aromatic moiety.

A convenient way to prepare such sulfonyl chloride materials is to react the carbonylated naphthyl compound or its substituted derivatives with chlorosulfonic acid in excess of the stoichiornetric amount needed for the particular extent of chlorosulfonation desired, heating to about C. for an hour (or even more drastic where plural chlorosulfonation is desired), pouring the reaction product on ice, then separating the organic material from the resulting aqueous layer. Normally solid sulfonyl chloride products are most easily filtered oil, and normally liquid ones decanted, but other conventional separation techniques can be used where necessary or desirable.

Frequently the needed proportion of instant su'lfonyl chloride sensitizer also can be incorporated directly into the vehicle as a unit of a further polymerizable monomer, oligo'mer, prepolymer, or polymer vehicle. In such instance, for example, the sulfonyl chloride compound has a reactable functional group on it such as a carboxyl group or an hydroxyl group. Typically, then, such sulfonyl chloride compound can be made to react with a further polymerizable material, e.g., glycidyl acrylate, either in monomeric form or already part of a preformed prepolymer or oligomer.

Typically the vehicles can constitute the entire deposit or a binder for solids to yield a cured product in the nature of a paint, varnish, enamel, lacquer, stain, or ink. Usually the vehicles are fluid at ordinary operation temperature (between about 30 F. and about 300 F. and advantageously between ordinary room temperature and about 180 F), and when polymerized by the UV. radiation, give a tack-free film or deposit that is durable enough for ordinary handling. In the cured state such vehicle is resinous or polymeric in nature, usually cross-linked. Uncured for application to a substrate or uncured on such substrate, such vehicle consists essentially of a monomer or mixture of monomers, or a further polymerizable oligomer, prepolymer, resin, or mixture of same, or a resinous material dispersed or dissolved in'a solvent that is copolymerizable therewith. Such solvent ordinarily is monomeric, but can be an oligomer (i.e., up to 4 monomer units connected) or prepolymer (mol weight rarely above about 2000). Oligomers and prepolymers should be understood herein as being polymeric in nature.

In the main such vehicles or binders are those which also are conventionally polymeriza'ble by free radicalinduced addition polymerization using peroxy or azo catalysis or .a redox system. Alternatively, however, the "binders can be a fluent material wherein the ultraviolet wave energy causes photochemical generation of a catalytic material or effects a rearrangement which starts a polymerization that continues until a usefuly polymerized deposit results. The useful vehicles can be polymeric, monomeric, or a mixture, especially those exhibiting polymeric, monomeric, or a mixture, especially those exhibiting polymerizable vinyl, acrylic, allylic, mercaptan, fumaric, .maleic, or like unsaturated functionality. lReactive polymeric types include unstaturated polyesters, acrylics, epoxies, urcthanes, and siliconcs. Representative polymeric 'vehicles include those derived from the reaction of dibasic acids or their anhydrides with polyols. 'For example, equimolar amounts of maleic anhydride and phthalic anhydride can be reacted with propylene glycol in slight excess to form an unsaturated polyester which can be extended with styrene to a pre-selected value of nonvolatiles (n.v.), generally between 50 and 80% n.v. The polyester resin thus prepared should have an acid number of about 60 and less. Of course, fumaric acid can be substituted easily for the maleic anhydride. Similarly, propylene oxide can be substituted for the major portion of propylene glycol. Also instead of styrene other active monomers such as hydroxyethyl-acrylate can be used, usually up to about 50% by weight.

As to acrylic and other polymers, they are trimethylolpropane triacrylate, pentaerythritol triacrylate, ethyleneglycol diacrylate, diacrylic acid adduct of the diglycidyl ether of bisphenol A (DER 332 diacrylate) a dior triisocyanate reacted with a hydroxy containing acryla'te such as hydroxyethyl or hydroxypropyl acrylate.

Reactive monomer types include a variety of acrylates such as hydroxyethyl, cyclohexyl, hydroxypropyl, 2-ethylhexyl, benzyl, phenoxyethoxy, lower alkoxyethoxy, tetrahydrofurfuryl, similar acrylates, and also N-vinyl pyrrolidone, vinyl acetate, vinyl acetate-butyrate, styrene and substiuted styrenes.

The instant sulfonyl chloride sensitizers are useful by themselves or in admixture with other sensitizers that are conventional such as benzoin, benzoin ethers, oxime ethers, and phosphines. Additionally, to enhance cure throughout the vehicle when the vehicle temperature is substantially above about 100 F. and such vehicle is particularly susceptible to such catalysis, a minute pro portion of a peroxy or like free-radical catalyst can be used.

Not only is the speed of U.V. curing quite good using the present sulfonyl chloride sensitizers, but also the depth of cure is quite practical so that the resultant polymerized deposit resists scratching or disruption when first ostensibly dry on the surface. Curing can continue on stored pieces. Typical film thickness for the deposit can be about 0.1 to as high as mils or even substantially higher, e.g., 30-50 mils. Preferred cured deposits are continuous films, but decorative or message-transmitting ones need not be.

Typically the substrate workpieces coated with the uncured deposit or deposits are passed under a U.V.- providing light beam by a conveyor. The substrate being coated can be metal, mineral, glass, wood, paper plastic, fabric, ceramic, etc.

Many useful pigments can be incorporated, in modest proportions,'into the vehicle Without much deleterious effects. Thus, opacifying pigments such as Zinc oxide can be used quite well. Titania, e.g., anatase and particularly rutile, makes for a such more difiicult film to cure by U.V. radiation, but such opacifying pigmentation can be used. Other filler materials and coloring pigments such as basic lead sulfate, magnesium silicate, silica, clays,

wollastonite, talcs, mica, chromates, iron pigments, Wood flour, microballoons, hard polymer particles, and even reinforcing glass fiber or fiake also are suitable in the vehicle to make a paint. Ordinarily it is most desirable to use 'pigmen'ts which do not absorb a great deal of U.V. wavelength in the same region of the U.V. spectrum as is absorbed by the instant sulfonyl chloride sensitizers. However, by use of adjunct energy-transferring, U.V.-sensitizing materials such as Michlers ketone in the sensitizing mixture, sufficient energy transfer often can be obtained to activate the instant sulfonyl chlorides and enhance the curing of pigmented systems. The wave length of U.V. should not, be too similar to or close to the wave length absorbed by the pigment in the U.V. range for best advantage of the irradiation process. Pigmented or filled films for the process preferably are no more than about mil thick and'generally about 0.1-0.5 mil thick, maximum, for efficiencyand economy of curing.

Where it is desirable to induce fusion or flow in a 'wet '(uncured) paint deposit such as a powder, followed by a polymerizing cure of the type available by use of the instant improvement, it can be advantageous to first Warm the deposit or substrate by a conventional method; e.g., forced or natural convection, electrical induction or with a source of infrared energy, then follow this with the U.V. radiation for cure.

The following examples show ways in which this invention has been practiced, but should not be construed as limiting it. Unless otherwise specifically stated herein, all parts are parts by weight, all percentages are weight percentages, and all temperatures are in degrees Fahrenheit. Where the binder being cured is of the type normally curable by free-radical polymerization, it is sometimes advantageous for completeness of cure and a speed to maintain a substantialy inert atmosphere above the irradiated workpiece; e.g., by a purge of nitrogen or other inert gas, but this is not required in all situations.

EXAMPLE 1 A clear coating of /3 part phenyl cellusolve acrylate, /3 part ethylene glycol diacrylate, and /3 part of trimethylolpropane triacrylate is prepared as the vehicle for test curing using a plasma arc radiation unit.

The curing apparatus is an intense radiation torch (plasma arc) optically directed by a reflector system to irradiate a freshly painted flat aluminum workpiece pass ing below a rectangular irradiating window on an en closed horizontal conveyor moving at various line speeds (providing about 0.2 second of irradiation at feet a minute and 0.1 second of irradiation at 200 feet a minute). The atmosphere around the workpiece during its irradiation is kept essentially inert by purging it with nitrogen. Radiation energy supplied by such apparatus at the workpiece surface is about 35 kilowatts per square foot with slightly less than about 6 kilowatts per square foot thereof being in the U.V. spectrum. Such sort of torch is described in US Pat. 3,464,387.

The above clear coating is applied to the aluminum workpiece (panel) as a film of about 0.4 mil thickness utilizing a wound wire rod #8. The coated panel is subjected to the radiation emitted by the apparatus described but the film does not cure completely even when exposure at line speed of 100 feet per minute is continued for times (total actual exposure time is 30 seconds). Incomplete cure of the film is recognized by being tacky to the touch.

The vehicle is dosed with 2% by weight of l-chloromethyl,6-chlorosulfonyl naphthyl-2 phenyl ketone well mixed in. The sensitized coating is spread at about 0.4 mil thick on the aluminum test panel and is cured at room temperature by subjecting it to the apparatus as above described. At line speeds of 100 and 200 feet per minute the vehicle cures tack-free and has a good scratch resistance to the fingernail, indicating good cure throughout the film depth.

EXAMPLE 2 In this operation the same apparatus, operation, and vehicle of Example 1 are used, except that 1% of the l-Chloromethyl,6-Chlorosulfonyl naphthyl-2 phenyl ketone is used. The results are substantially the same.

EXAMPLE 3 In this operation the same apparatus, operation, and vehicle of Example 1 are used, except that 2% 4-methoxy,5- Chlorosulfonyl naphthyl-2 methyl ketone is used. The results are approximately the same as Example 1, even the amount of the sensitizer is reduced to 1% by Weight.

EXAMPLE 4 In this example, the same apparatus, operation, and vehicle of Example 3 are used including the sensitizer WhlCh is combined with 0.3% of Michlers ketone. The

results are substantially the same as in the preceding examples.

EXAMPLE Similar to Example 4 a 2% mixture comprising 1.7% of fi-chlorosulfonyl phenanthryl-9 phenyl ketone and 0.3% Michler ketone is used. The results show identical curing characteristics.

EXAMPLE 6 A clear vehicle is prepared from part pentaerythritol triacrylate, /s part hydroxyethyl acrylate, and /3 the adduct formed by reacting one mol of toluenediisocyanate with 2 mols of hydroxyethyl acrylate.

The curing procedure is carried out in the same manner described in Example 1. Without the incorporation of any sensitizers no curing (hardening) of the coated film (0.5 mil) is observed even with repeated exposures to the U.V.

EXAMPLE 7 Into each of the clear vehicles of Examples 1 and 6 there is incorporated by weight of zinc oxide. The now pigment vehicles are sensitized individually by 2% of the chlorosulfonated naphthyl and phenanthryl ketones of the preceding examples. Irradiated in the same manner as described in Example 1 the pigmented films cure to tack-free state at line speed of 100 feet per minute.

EXAMPLE 8 In the clear vehicles of Examples 1 and 6 there is incorporated 20% by weight of titanium dioxide (anatasc). The pigmented vehicles are spread in 0.4 mil thick films on aluminum panels. Also reduced to comparably thin films are the pigmented vehicles in two parts. One has 1-Chloromethyl,6-chlorosulfonyl-naphthyl-Z phenyl ketone as a sensitizer.

0n exposure to the apparatus described in Example 1 the only films to cure tack-free are those which contain the sensitizer of the invention. By comparison l-chloromethyl naphthalene, as well known sensitizer, is incorporated at 2% into the same pigmented vehicle. No hard cure is observed at multiple passages of the coated panel at 100 feet per minute.

EXAMPLE 9 A polyester vehicle is prepared from 3 mol phthalic anhydride, 3 mol maleic anhydride, 6.8 mol propylene glycol and cooked to an acid number of about 30. Styrene is added until 70 n.v. (non-volatiles) is attained. Into the above clear polyester vehicle 2% by weight of l-chlorosulfonyl anthracyl-9, phenyl ketone. Exposure of panels coated to 0.5 mil thick to irradiation at line speed of 100 feet per minute gives complete and tack-free cure.

EXAM PLE 1 O A polyester vehicle is prepared from 3 mol maleic anhydride, 3 mol phthalic anhydride, 1 mol propylene glycol, and 6 mol propylene oxide and cooked to an acid number of about after which hydroxyethylacrylate is added to constitute by weight of the entire vehicle.

Into the above vehicle 2% by weight of 2-chlorosulfonyl phenanthryl-3 phenyl ketone is incorporated, followed by applying the vehicle to test panels as earlier described. subjecting the coated panels to the radiation emitted by the apparatus of Example 1, at line speed'of 100 feet per minute produces tack-free, scratch resistant films. Without said sensitizer the film is wet and tacky even after repeated exposures to radiation.

EXAMPLE 1 1 A vehicle comprising pentacrythritol tri-acrylate is sensitized by 2% S-chlorosulfonyl naphthyl-l phenyl ketone. Substantially the same excellent cure is obtained for 0.4 mil thick films at both line speeds of 100 and 200 feet per minute.

8 EXAMPLE 12 The same vehicle of Example 11 is sensitized with 2% 1-bromomethyl-6 chlorosulfonyl naphthyl-2 phenyl ketone with the results being substantially comparable when the same procedure is followed. I

EXAMPLE 13 A clear vehicle is prepared from /2 phenylcellulose acrylate and /2 pentaerythritol triacrylate. 2% of chlorosulfonated phenanthrene phenyl ketones is incorporated into said vehicle which is applied to a test panel as a film of about 1 mil thick. The ketones represent a mixture of monochlorosulfonated material wherein the substitution is at the 2, 6, 7 or 8 position. Following the irradiation procedure described in the preceding examples the film cures to a tack-free state at a line speed of feet per minute.

EXAMPLE 14 A vehicle is prepared from /3 pentaerythritol triacrylate, /5 Z-diacrylate. Also incorporated into said vehicle is sufficient titania (rutile) to make up a paint with a pigment to vehicle ratio of 0.8 to 1.0. Into said paint there is incorporated 2% by weight, based on vehicle, S-chlorosulfonyl, 8-bromomethyl naphthyl-Z phenyl ketone and 0.3% by weight, based on the vehicle, of Michler ketone. The sensitized paint is applied in films of about 0.4 mil thick and irradiated in the same manner described earlier. The paint cures to a tack-free state at line speed of 200 feet per minute.

EXAMPLE 15 The vehicle described in Example 14 is prepared again to contain 3% by weight iron black (ferric oxide) making the now colored vehicle suitable as a printing ink. The colored vehicle is applied in a film of about 0.3 mil thick which is then subjected to the apparatus substrate described at 100 feet per minute. The cure is full and complete; no smudging is observed.

EXAMPLE l6 Into a vehicle comprising acrylated soybean oil (available commercially from Union Carbide Corporation, New York, N.Y. as Flexol Plasticizer EPO) is incorporated a 2% 4-methoxy, S-chlorohulfonyl Z-naphthyl methyl kotone. The sensitized vehicle is applied to a heat sensitive plastics substrate (high density polyethylene) in a thin film of about 0.6 mil thick. The coated plastics substrate is then subjected to the curing procedure described above at 100 feet per minute. The coated film shows full cure and the substrate shows no distortion.

What is claimed is:

1. In a process for polymerizing an ethylenically un saturated photopolymerizable vehicle in which a pigment is dispersed to form a pigmented composition, by exposure to U.V. radiation, the improvement which comprises incorporating into said vehicle about 0.5-5% by Weight of a carbonylated polynuclear sulfonyl chloride, said pigment being from about 20% to about 50% of said composition.

2. The process of claim 1 wherein said sulfonyl chloride is represented by the general formula:

Wherein R is hydrogen, alkyl (C ),.ot -haloa1kyl (C phenyl and substituted phenyl wherein the substituent is alkyl, alkoxy, ot-haloalkyl or chlorosulfonyl, polynuclear aromatic radical, R and R represent hydrogen, one or more fused rings, alkyl (C and a-haloalkyl, and n is a number of at least 1.

3. The process of claim 2 further characterized by said sulfonyl chloride wherein said R is phenyl and n is 1.

4. The process of claim 2 further characterized by said sulfonyl chloride wherein R is phenyl, R is hydrogen and R is a fused ring.

5. The process of claim 2 further characterized by said sulfonyl chloride wherein said R is alkyl (C R is a-haloalkyl (C and R is hydrogen.

6. The process of claim 2 further characterized by said sulfonyl chloride wherein R is alkyl (C R is alkoxy and R is hydrogen.

7. The process of claim 2 further characterized by said sulfonyl chloride wherein R is phenyl, R is a-haloalkyl (C and R is a fused ring.

References Cited UNITED STATES PATENTS 3,702,812 11/1972 McGinnis s 204159.24

10 2,579,095 12/1951 Sachs et al. 204159.24 3,113,024 12/1963 Sprague et al. 9685 US. Cl. X.R.

96-115 P; l1793.31, 142 R, 132 R, 138.0 R, 143 A; 204159.14, 159.16, 159.18, 159.23; 26025 B, 39 P, 39 M, 395 SB, 41 A, 41 B, 41 C, 41 AB, 77.5 CR, 80.75, 80.81, 86.1 E, 851, 856