CA1078098A

CA1078098A - Radiation curable coatings

Info

Publication number: CA1078098A
Application number: CA252,082A
Authority: CA
Inventors: Joseph C. Reilly
Original assignee: Rohm and Haas Co
Current assignee: Rohm and Haas Co
Priority date: 1975-05-20
Filing date: 1976-05-10
Publication date: 1980-05-20
Also published as: DE2622022A1; AU1414076A; GB1550382A; JPS51140932A; AU510012B2; IT1070098B; FR2311804A1

Abstract

ABSTRACT OF THE DISCLOSURE

Isobornyl acrylate, a low viscosity, low volatility, low shrinkage and relatively nontoxic material has been found to be an excellent reactive diluent for radiation curable coatings or ink vehicles as well as a radiation curable coating itself.

Description

~0~7809~

This invention relates to new radiation curable coating and ink compositions comprising isobornyl acrylate.
More particularly, it relates to employing isobornyl acrylate as a reactive diluent.
It is well known in the art to deposit polymerizable liquid coatings on substrates and then to dry and cure such coatings by passing them through ovens to crosslink the coatings. It is also known in the art to use coatings which are curable by exposure to actinic radiation such as ultra-violet rays or that from plasma arc radiation sources, awell as by exposure to high energy ionizing radiation such as electron beam radiation. These systems have disadvantages in that either ovens are required or tha~, in radiation curable coatings, oxygen inhibition of the polymerization of the coating may occur, or it may be necessary to employ solvents to decrease the viscosity of the coating for application purposes.
Due to energy and r~w material shortages, increas-ingly strict air pollution standards and safety regulations, the search is continuing for one hundred percent polymeriz-able system~, i.e., compositions which have no highly volatile components bu~ which contain reactive viscosity reducing diluents which become either the 801e cur~d film or part of the cured film. Such types of compositions are known, for example, multifunctional acrylates, meth-acrylates and itaconates of pentaerythritol, dipentaeryth-ritol and polypentaerythritols and others disclosed ~n U. S.
Pat. Nos. 3,551,235; 3,551,246; 3,551,311; 3,552,986;
3,553,387 and 3,661,614.
Two U. S. patents which disclose radiation cure of monofunctional acrylates are U. S. Pat. No. 3,783,006.

-2-which describes a wide number of acrylate monomers for use as diluents in polymer syrups which are cured on metal containers via electron beam radiation and U.S. Pat. No. 3,772,062 which also describes the use of various diluents in the curable coatings. Still anoth~r patent which pertains to curing of acrylic compounds by radiation is U.S. Patent 3,840,448.
The instant invention relates to the use of isobornyl acrylate as a radiation curable coating, as a reactive diluent in 100~ curable systems and also coatings formed therefrom.
Isobornyl acrylate is a known compound. One method of preparation is by the method disclosed in U.S. Pat. No.

3,087,962 of Bortnick, granted April 30, 1963.
Other low volatility acrylate monomers are available such as trimethylolpropane triacrylate, pentaerythritol tri-acrylate, neopentylglycol diacrylate and the like; however, these, unlike isobornyl acrylates, cure to highly crosslinked and extremely hard, b~ittle films. Isobornyl acrylate yields a relatively hard polymer (Tg=94C.) but unlike the hard multifunctional acrylates does not contribute to increased crosslink density. Higher alkyl acrylates such as lauryl acrylate, isodecyl acrylate and, marginally, 2-ethylhexyl acrylate have the desired lower volatility and viscosity but their use alone as a diluent tends to promote excessive softening.
However, in combination with isobornyl acrylate one can achieve an excellent degree of latitude of hardness and flexibility and viscosity control previously unobtainable with other combinations of acrylates. The polymerization of isobornyl acrylate is accompanied by low volume shrinkage relative to other known reactive diluents thereby aiding and minimizing losses in adhesion and flexibility 1(~7809~

commonly observed in radiation curable systems. In addition, to these improvements, isobornyl acrylate is of relatively low toxicity, compared to many other ethylenically unsaturated monomers in common use.
The radiation curable compositions of this invention comprise:
a. from about l to about 99.9~ by weight of isobornyl acrylate with the preferred compositions containing from about 10 to about 98% by weight of isobornyl acrylate;
b. from 0.1 to 25% by weight of a photoinitiator, and preferably from about l to 15~ by weight of a photoinitiator;
c. from 0 to 99% by weight of another ethylenically unsaturated monomer, oligomer or polymer or mixture thereof, and, when employed, preferably from 5 to 95% by weight;
d. from 0 to 80~ by weight of a nonradiation reactive oligomer, polymer or mixture thereof, and, when employed, preferably from 5 to 50% by weight;
e. from 0 to 90~ by weight of a pigment, and, when employed, preferably from 2 to 80~ by weight; and f. from 0 to 50~ by weight of a plasticizer, and, when employed, preferably from 5 to 40~ by weight.
The ethylenically unsaturated monomers, oligomers and polymers employed with isobornyl acrylate may be any of the ~nown radiation polymerizable coating materials. Isobornyl acrylate has been shown to be compatible with acrylate pendant polymers, such as acrylated epoxies, acrylated oils, acrylated urethanes, unsaturated polyesters, neopentyl glycol diacrylates;
pentaerythritol triacrylate; trimethylol propane triacrylate;
1,6-hexane diol diacrylate;

10780~8 2-ethplhexyl acrylate; isodecyl acrylate; hydroxyethyl acrylate; ROSKYDALTM 650 polyester (MOBAY); ActomerTM X-70 tan acrylate functional polyester oligomer (Union Carbide) Epoc~yl DRH 303.1 M, the diacrylate ester of a bisphenol A epoxy resin (Shell) and the like.
In addition to the use of isobornyl acrylate as a reactive diluent at low to modestly high concentration in coating compositions containing reactive resins, crosslinking monomers or other monofunctional monomers, it also has considerable utility as a major if not the sole polymeriz-able component of a radiation curable coating. While very low viscosity may aid in some of these applications, e.g., for ease of surface penetration and binding to materials such as wood, leather, paper and cement, it may be desirable to add up to 80~ by weight of a nonradiation reactive polymer, oligomer or mixture thereof of certain higher viscosity resins strictly for rheological control, i.e., as "thickeners".
The resins do not necessarily have to be reactive in this capacity. Where the hardness of polymerized isobornyl acrylate i9 not required or desired, low viscosity systems of les~ hardness may be prepared by ~udicious addition of softer, low viscosity polymers. Examples of these resins include polymers of lower alkyl acrylates and methacryl~tes wherein the alkyl has from 1-5 carbon atoms such as methyl, ethyl, propyl, butyl, pentyl and the like.
I desired, isobornyl acrylate can be made into soft, flexible films by the use of inert, nonvolatile plasticizers in the range of from 5 to 50~ by weight.
Plasticizers which can be employed include phthalate esters such as dibutyl, dioctyl, di-2-ethylhexyl, butylbenzyl diisodecyl esters, SanticizerTM 262 (Monsanto) and the like;
adipate esters such as dioctyl and the like; phosphates such as tributoxyethyl, tributyl, tricresyl and the like; phthalyl glycolates such as butyl phthalyl butyl glycolate; sulfonamides such as N-ethyl-o-~-toluenesulfamide and the like; also included are castor oil and its derivatives and polymeric types such as those disclosed in the Rohm and Haas Company booklet "Paraplex~
and Monoplex~ Plasticizers - summary of physical performance properties" published May 1968.
The acrylate based photocurable monomers, polymers and oligomers are generally preferred because of higher cure speed.
~ he ethylenically unsaturated portion of the composi-tion other than isobornyl acrylate which comprises 0-99% by weight of the composition comprises one or more acrylate monomers or oligomers or polymers thereof; i.e. at least one monomer (or an oligomer or polymer derived from said monomer) of the formula:

R O
H2C=C-e-O-R
I

wherein R is hydrogen or methyl and Rl is an alkyl group of from 1 to 18 and preferably from 1 to 12 carbon atoms such as methyl, ethyl, propyl, isopropyl, butyl, hexyl, 2-ethylhexyl decyl, isodecyl, dodecyl, octadecyl and the like, aryl, for example, mononuclear aryl, such as benzyl, phenyl and the like, cyclo-alkyl, for example, cycloalkyl of from 5 to 12 nuclear carbon atoms such as cyclohexyl, trimethyl cyclohexyl, cyclopentyl, cycloctyl, dicyclopentenyl and the like, substituted aryl or substituted cycloalkyl wherein the substituent is alkyl, halo, hydroxy and the llke or Rl is 809~
~2 ~ R ~ Rl wherein R is an alkylene radical of from 1 to 8 carbon atoms such as methylene, ethylene, propylene isobutylene and the like, and z is a whole number from 2 to 25, or Rl is -( R2 CO -- ~ Rl I z III
wherein R and z are as described above.
Typical of the acrylic monomers which may be employed in this invention include monoacrylates, such as methyl acrylate, isopropyl acrylate, cyclopentyl acrylate, 2-ethylhexyl acrylate, decyl acrylate, isodecyl acrylate, decyl thioacrylate, dodecyl acrylate, o~tadecyl acrylate, hydroxyethyl acrylate, hydroxybutyl acrylate and the like;
diacrylates, such as ethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, neopentyl glycol diacrylate, 1,6-hexane diol diacrylate, polypropylene glycol diacrylate, 1,3-butane diol diacrylate, 1,4-butane diol diacrylate and the like; triacrylates such as tri-methylol propane triacrylate, pentaerythritol tiracrylate and the like or tetraacrylates such as pentaerythritol tetraacrylate and the like.
In general, a photoinitiator or sensitizer is added to the composition before exposing the coatings to actinic energy. The photoinitiators or sensitizers, when used, are employed in the amounts of about 0.1 to about 25%
by weight and preferably from about 1 to 15% by weight 1~78Z)98 of the total polymerizable compositions. Preferred photoini-tiators employed include selected acyloins or derivatives thereof, for example, benzoin alkyl ethers such as benzoin methyl ether, benzoin ethyl ether and the like, decyl halides such as decyl bromide, decyl chloride and the like, decyl amine, benzophenone derivatives, acetophenone compounds, polychlorinated aromatic compounds, a combination of organic carbonyls and amines or mixtures thereof. The acetophenone photoinitiators are disclosed in U.S. Pat. No. 3,715,293 of C.L. Osborn et al, granted February 6, 1973; while the combination of organic carbonyls and amines is disclosed in U. S. Patent No. 3,759,807 of C.L.
Osborn et al, granted September 18, 1973, both patents being assigned to Union Carbide Corporation.
The compositions of this invention are dried or cured by exposure to radiation. The compositions exhibit maximum sensitivity in the range of from about 1800 to 5000 A and any source of actinic light can be employed. In addition, electron beams, gamma radiation emitters and the like can be employed instead of a photoinitiator in which case there may be from 1 to 100% by weight of isobornyl acrylate. Suitable sources of radiation include carbon arcs, mercury-vapor arcs, fluorescent lamps with ultraviolet light emitting phosphors, argon glow lamps, photographic flood lamps, Van der Graaf accelerators, resonant transformers, betatron linear accelerators, gamma radiation emitters and combinations thereof.
The photopolymerizable coating compositions of the present invention are useful as coatings such as an adhesive, a marker, a vehicle for printing inks, lacquers and paints on various substrates including metals, ceramic, cement, wood, plastics, textiles, paper, floor tiles, glass, roads, parking lots, airfields and the like. The compositions are also useful in the preparation of photopolymerizable 1~7809~ , elements, i.e., a support having disposed thereon a photopoly-merizable layer of a composition as described herein. Moreover, various dyestuffs, pigments, plasticizers, lubricants and other modifiers may be incorporated to obtain certain desired charact-eristics in the finished products.
When a photopolymerizable composition of the present invention is used as an adhesive, at least one of the lamina must be translucent when ultraviolet light is used. When the radia-tion source is an electron beam or gamma radiation at least one of the lamina must be capable of transmitting high energy elec-trons or gamma radiation respectively, and neither is necessarily translucent to light. Typical laminations include polymer coated "Cellophane"* to polymer coated cellophane films, treated polyethylene to treated polyethylene films, "Mylar"** to a metal substrate such as copper and the like, opaque oriented poly-proylene to aluminum or polymer coated "Cellophane"* to poly-propylene.
The photopolymerizable compositions of the present invention may be utilized for metal coatings such as in coil coating a~d in metal decorating. For example, in metal decorat-ing isobornyl acrylate is useful in formulating pigmented base coats, inks and clear overprint varnishes. Glass and plastics may also be coated and the coatings are conventionally applied by dip coating, direct and reverse roller spray. Pigmented coating systems may be used for various polyester and vinyl films;
polymer coated "Cellophane"*, glass, treated and untreated poly-ethylene, for example, in the form of disposable cups or bottles;
and the like. Examples of metals which may be coated include sized and unsized tin plate, tin free steel, aluminum and the like.

_g_ 107~

*Trademark for a brancl of regenerated cellulose film produced from viscose by treatment with sulfuric acid and/or ammonium salts.
** Trademark of DuPont for a polyester film of very high tensile strength.

-9a-09~

The compositions may be pigmented with organic or inorganic pigments, for example, molybdate orange, titanium white, chrome yellow, phthalocyanine blue and carbon black, as well as colored with dyes. Stock which may ~e 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, for example, in vehicles for textile printing inks or for specialized treatments ~f fabrics to produce water repellency, oil and stain resistance, crease resistance and the like. A general ink formulation would be the vehicle of the composition of 1-99~ -by weight of icobornyl acrylate, 0-99~ by weight of an ethylenically unsaturated monomer, oligomer or polymer or mixture thereof, 0-25% by weight of photoinitiator and 0.1-90~ by weight of pigment based on the total vehicle ink composition.
Photopolymerizable elements of this invention comprise a support, for example, a sheet or plate, having superimposed thereon a layer of the above described photo-polymerizable compositions. Suitable base or support materials include metals, for example, steel and aluminum plates, sheets and foils. Also films or plates composed of various film forming synthetic resins or high polymers, such as addition polymers and, in particular, vinyl polymers, for example, vinyl chloride polymers; vinylidene chloride polymers; vinylidene chloride copolymers with either vinyl chloride, vinyl acetate or acrylonitrile; and vinyl chloride copolymers with vinyl acetate or acrylonitrile; linear condensation polymers such as polyesters, for example, polyethylene terephthalate; polyamides, and the like.

Fillers or reinforcing agents can be present in the _ln_ 1~)'7~0'~8 synthetic resin or polymer bases. In addition, highly reflective bases may be treated to absorb ultraviolet li~ht or a light absorptive layer can be transposed between the base and photopolymerizable layer.
Photopolymerizable elements can be made by exposing to ultraviolet light selected portions of the photopolymerizable layer thereof until addition polymeriza-tion is completed to the desired depth in the exposed por-tions. The unexposed portions of the layer are then removed, for example, by use of solvents which dissolve the monomer or prepolymer but not the polymer.
As stated above, any suitable source of actinic energy may be used, for example,, a 200 watt/lineal inch, medium pressure, mercury arc source. Factors varying the rate at which a photopolymerizable composition will dry include the specific in~redients in the composition, concentration of the photoinitiators, thickness of the material, nature and intensity of the radiation source and its distance from the material, the presence of absence of oxygen and the ambient temperature.
The compositions of the present invention are generally employed as films having a thickness of from about 0.1 to about 30 mils, and preferably from about 0.2 to 10 mils. The compositions of the invention can also be employed to form sheets of various thickness, for example, sheets having a thickness of from about 30 to 1000 mils.
The following examples and tables illustrate the preparation, curing, relative curing rates and physical properties of the novel compositions of this invention.
Unless otherwise noted, all percentages are parts by weight.

~13'780~

The following is a list of either how various tests were conducted or a reference to where the test~
are described:
Viscosity -Where reported in centipoise (cps.), viscosities were determined with a Brookfield Viscometer at room temperature. "Paint Testing Manual", Gardner and Sword, 12th edition, 1962, p. 178.
Where reported in centistokes, viscosities were determined with Gardner Bubble Standards. "Paint Testing Manual", Gardner and Sword, 12th edition, 1962, p. 172.
Tukon Hardness -"Paint Testing Manual"' Gardner and Sword, 12th edition, 1962, p. 135.
Pencil Hardneys Test -"Paint Te~ting Manual", 12th edition, Gardner and Sword, 12th edition, 1962, p. 147.
Gardner Impact Test -"Paint Testing Manual", Gardner and Sword, 12th edition, 1962, p. 147.
Mar Resistance Test -Mar resistance was determined by lightly scratching the coating surface with the back of a fin~ernail (a commonly accepted practice in the coating industry).
Cross-cut Adhesion Test -"Paint Testing Manual", Gardner and Sword~ 12th edition, ~962, p. 160.
Water Immersion Test ~150F.) -The water immersion test at 150F. for 30 minutes simulates pasturization of a beer can coating and measures a coatings resistance to blushing, blistering and/or loss of adhesion.

1(~78098 EXAMPLE 1 - Composition of Isobornyl acrylate, Penta-erythritol triacrylate and 2-Ethylhexyl acrylate The four 100% polymerizable clear protective liquid coatings of the compositions disclosed in Table I (infra) are prepared by admixing the components in the order given in conventional equipment until clear and homogeneous. The coatings are then applied to aluminum test panels ("Alodine"*
1200S) by drawdown to yield films of 1.5 mil thickness and, finally, cured to a dry, tack free state by passage at 7.5 feet per minute under two 200 watt/lineal inch "Hanovia"** medium pressure mercury arc lamps mounted in parabolic reflectors.
The cured films are evaluated for Tukon indentation hardness, pencil hardness and impact strength. The finds evidence the improved balance of coating viscosity, film hardness and film toughness that is achieved employing isobornyl acrylate.

*Trademark **Trademark !

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EXAMPLE 2 - Metal Coating of Isobornyl acrylate, Penta-erythritol triacrylate and Actomer X-80 A 100~ polymerizable liquid coating useful as a protective coating for metal is prepared by mixing, until clear and homogeneous, Actomer R X-80, a high viscosity acrylate functional resin (Union Carbide) with isobornyl acrylate, pentaerythritol triacr~lgte (crosslinker) and benzophenone/methyl diethanolamine (photosensitizer system) in the proportions given below:
Coating Composition Parts by Weight Actomer X-80 40 Isobornyl acrylate 40 Pentaerythritol triacrylate 20 Benzophenone 2 Meth~l diethanolamine 3 The liquid coating (viscosity - 350 centi-stokes) was applied to aluminum test panels by a wire wound rod to yield a film thickness of 0.25 mils and then cured by the procedure described in Example 1. The cured coating (pencil hardness 2H) has excellent mar resistance, adherence and is unaffected by immersion in water at 150F.
for one hour, EXAMPLE 3 - Coating of Isobornyl ac~ylate and Epocryl DRH-303.1 A 100% polymerizable liquid coating is prepared by mixing until clear and homogeneous Epocryl DRH-303.1, a high viscosity diacrylate ester of a bisphenol A epoxy resin (Shell), with isobornyl acrylate and diethoxyacetophenone (photosensitizer) in the proportions given below.
oating Composition Parts by Weight Epocryl DRH-303.1 45 Isobornyl acrylate 55 Diethoxyacetophenone 2 107809~

The liquid coating has a viscosity of about 350 centistokes and is applied to aluminum test panels by wire wound rod to yield a film thickness of 0.25 mils and then cured by the procedure described in Example 1. The cured coating (pencil hardness 2H0 has very good mar resistance, adherence and is unaffected by immersion in water at 150F.
for 1 hour.

EXAMPLE 4 - Comparison of Isobornyl acrylate with Styrene and Isoborn~l methacrylate The utility of iiobornyl acrylate as a diluent monomer for 100~ polymerizable unsaturated polyester coatings conventionally employing styrene diluent is afforded by the comparative cure results of Table II. Therein, the unsaturated polyester resin Roskydal 650 M (Mobay) was dissolved in styrene, isobornyl acrylate, as well as in isobornyl methacrylate to demonstrate the cure speed advantage of the preferred acrylate moiety. The coatings were cast to yield 1.5 mil films on aluminum test panels and cured as described in Example 1.

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EXAMPLE 5 - Composition of Isobornyl acrylat~, 2-Ethylhexyl acrylate and Actomer X-80 A lO0~ polymerizable coating is prepared by admixing the following ingredients until clear and homo-geneou6. The so~ution has a viscosity ~f 340 centistokes:
Coating ComPosition Parts by Weight Actomer X-80 60 Isobornyl acrylate 20 2-Ethylhexyl acrylate 20 Methyl diethanolamine 3 Benzophenone 2 The liquid coating is filmed with a No. 40 wire wound rod on a piece of commercial vinyl asbestos type flooring tile and cured as described in Example l to afford a glossy, resilient, mar resistant and adherent protective fini8h on the tile.
EXAMPLE 6 - Isobornyl acrylate with Nonradiation Reactive Pol mers V

The compositions of Table III are prepared by admixing the components in conventional equipment until clear and homogeneous. The wet coatings are applied with a No. 4 wire wound rod to aluminum test panels (0.25 mil film thickness) and cured as described in Example l.

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EXAMPLE 7 - Coating of Concrete and Wood Composition A of Example 6 is applied by wiping a thin layer on a concrete test slab and a wood test slab. The slabs were then cured by the procedure as described in Example l to yield water repellent, protective hard finishes on both substrates.
EXAMPLE 8 - Rates of Volatilization The volatility characteristics of isobornyl acrylate is compared with other diluent monomers. Seven (7) cm. diameter circles of "Whatman"* No. 1 filter paper is saturated with monomer (ca. l-1.3 gm.) and weight loss is monitored as a function of time, the specimens being places in a laboratory hood of modest air velocity. Weight loss versus time is linear through at least 80% loss of the samples. The resulting rates of weight loss, expressed in milligrams per minutes from the specified samples are given below.

Rate of Volatilization Monomer (mg./min.) Styrene 19 20 Butyl acrylate 17 Cyclohexyl acrylate l.9 2-Ethylhexyl acrylate 0.5 Isobornyl acrylate 0.25 Isodecyl acrylate 0.1 *Trademark '` 1078098 EXAMPLE 9 - Isoborn.~l acrylate Compositions with Plasticizers mposition (Wt.) A B C
Isobornyl acrylate 100 95 90 Santicizer 2621 0 5 10 5 2,2-Diethoxyacetophenone 2 2 2 _ red Film ProPerties Knoop Hardness 14 10 ~.4 M~ndxel Fl3x.ibility ~ 6 > 6 4 (diameter passed, in.) lSanticizer 262 is a monomeric phthala'e type plasticizer (Monsanlo) ~f undisclosed composition ha-~ing a molecular weight OI 396. 5.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A radiation curable coating composition comprising:
(a) from 1 to about 99.9% by weight of isobornyl acrylate;
(b) from 0.1 to 25% by weight of a photoinitiator;
(c) from 0 to 99% by weight of another ethylenically unsaturated monomer, oligomer or polymer or mixture thereof;
(d) up to 80% by weight of a nonradiation reactive oligomer, polymer or mixture thereof;
(e) from 0 to 90% by weight of a pigment; and (f) from 0 to 50% by weight of a plasticizer; the proportions of ingredients (a)-(f) above being selected so as to add up to 100% of said composition.

2. A composition according to claim 1 comprising:
(a) from about 10 to about 98% by weight of isobornyl acrylate;
(b) from 1 to 15% by weight of a photoinitiator;
(c) from 0 to 99% by weight of another ethylenically unsaturated monomer, oligomer or polymer or mixture thereof;
(d) up to 80% by weight of a nonradiation reactive oligomer, polymer or mixture thereof;
(e) from 0 to 90% by weight of a pigment; and (f) from 0 to 50% by weight of a plasticizer.

3. The composition of claim 2 wherein the photo-initiator is benzoin alkyl ether; decyl halide, decyl amine, benzophenone derivative, acetophenone compound, polychlorinated aromatic compound, or a combination of organic carbonyls and amines or mixtures thereof.

4. The composition of claim 2 having from 5 to 95%
by weight of an ethylenically unsaturated monomer, oligomer or polymer or mixture thereof.

5. The composition of claim 2 having from 5 to 50%
by weight of a nonradiation reactive oligomer, polymer or mixture thereof.

6. The composition of claim 2 having from 2 to 80% by weight of a pigment.

7. The composition of claim 2 having from 5 to 40%
by weight of a plasticizer.

8. A method of coating which comprises applying the composition of claim 1 to a substrate, and curing or drying by exposure to radiation.

9. The method of claim 8 wherein the coating is dried or cured by electron beam.

10. The method of claim 8 wherein the coating is dried or cured by actinic light.

11. A substrate having thereon a cured coating formed of the composition defined in claim 1.

12. A substrate according to claim 11 wherein the cured coating is from 0.1 to about 30 mils thick.

13. A substrate according to claim 11 wherein the cured coating is from 0.2 to 10 mils thick.

14. A sheet prepared from a composition as defined in claim 1.

15. A sheet as in claim 14, said sheet having a thickness of from 30 to 1000 mils.