Note: Descriptions are shown in the official language in which they were submitted.
.3~
This invention relates to radiation~curable compositions.
More particularly, the invention relates to actinic radiation-
curable compositions characterized by a reduced sensitivity to
oxygen inhibition during the curing process.
During the latter part of the past decade, significant
advances have been made in the radiation processing of commercial
products. The increased interest in energy-curable systems has
been catalyzed by recently impending legislation by federal, state
and local governments which restrict the amount of solvent and
other pollutants that can be vented to the atmosphere, and the
increased concern expressed by individuals and unions over the
possible toxic effects of prolonged ~xposure to volatile organic
materials, as well as the sky-rocketing cost of solvents derived
rom petroleum coupled with a grim prospect of material unavail-
ability. Generally, the energy-curable systems are 100~ reactive
systems, i.e., substantially all of the components react to pro-
duce the final product. As is well-known, the curing of such
systems can be effected by several means, including exposure to
high energy ionizing radiation; photopolymerization by actinic
radiation in the presence of a photoinitiator; and by exposure to
chemical free radical-generating agents, usually at an elevated
temperature. A particular deficiency of all radiation curable
compositions which cure via a free radical addition mechanism is
a sensitivity to
'
~3~
-- 2 --
oxygen inhibition during the curing process. Oxygen inhibition is not a serious
problem when cure is effected by exposure to high energy ionizing radiation or
by exposure to thermally-activated free radical-generating agents Oxygen
inhibition does materialLy affect compositions which are cured by exposure to
5 actinic radiation, such as ultraviolet light.
A typical actinic radiation-curable resin system contains an oLigomer,
which may or may not contain reactive functional groups (such as double bonds),
a crosslinking agent, a reactive diluent for viscosity control, and a photo-
sensitizer or photoinitiator. By selecting an oligomer which contains at least
10 two points of reactive unsaturation, or a reactive diluent which likewise contains
at least two points of reactive unsaturation, one may eliminate khe need or a
crosslinking agent per se. Control over the properties of the cured systems can
be exercised via the structure of the oligomer backbone, incLuding such factors
as degree of chain-branching, types o-f functional groups, number and types of
15 unsaturated bonds, molecular weight, etc.; functionality and level of cross-
linking agents; nature and level of reactive diluent; kind and level of the
sensitizer or photoinitiator; and the like. An exemplary oligomer which has
obtained widespread commercial acceptance and which can be cured by exposure
to actinic radiation in the absence of a crosslinking agent per se is an unsaturated
20 urethane oligomer obtained by react~g an isocyanate-~unctional prepolymer with
unsaturated cornpounds containing an isocyanate-reactive active hydrogen group.
Before any polymerization can occur, free radicals must first be produced via
the photoinitiator. The production of free radicals by the photoinitiator is a wave
length function of the actinic radiation. Once the radicals are formed, propagation
25 of polymer growth rapidly advances through chain reaction. Oxygen in the ground
or unexcited state is itself a radical and is highly reactive with other radicals.
Thus, chain growth can be terminated by the oxygen radical, resulting in uncuredor tacky surfaces and~ more ir~portantly, the photoinitiator itself when in the
~- free radical state can be capped and rendered inef~ective. In addition, the
30 presence of oxygen has a retarding effect on the cure rate.
` 1~13~34
3 --
The adverse effect of oxygen inhibition can be at least reduced by curing
in an inert gaseous environment (nitrogen, argon, carbon dioxide, and the like).While effective, the use of inert gas environments is generally cumbersorne and
economically unattractive. Other methods which have been suggested for reducing
5 the air inhibition effect on actinic energy-curable compositials include improved
design of energy sources, increasing photoinitiator level, use of more reactive
diluent systems, and use of natural and synthetic waxes. Except for the im-
proved energy sources which must be proved out, the suggested methods directly
affect ultimate properties of the cured systems and are not susceptible to wide-
10 spread utilization. There remains a compelling need for means to reduce thesensitivity of actinic radiation-curable composicions to oxygen inhibition during
the curing process. There is also a need to increase the rate of curing in both
inert and ox~gen-containing environments, and especially the latter.
An approach takerl with some success in the prior art, both with respect
15 to air-cure capability and cure rate, has been through modification of the photo-
catalyst system. For example, Gruker U. S. A. Patent No. 4, 017, 652 discloses
that oxygen inhibition of the photopolyrnerization of resins containing acrylic
groups can be abated by employing a photocatalyst system containing (1) as a
photosensitizer, at least one aromatic ketone or aro~atic aldehyde ~hich has a
20 triplet energy in the range of :i~om about 54 kilocalories per mole to about 7~
kilocalories per mole and which promotes polymerization through bimolecular
photochemical reactions of the energy donor type; and (2) as a photoinitiator~
at least one aromatic ketone which generates a radical pair by way of unimolecular
homolysis resulting from photoexcitation. A preferred photocatalyst system is
25 benzophenone and isobutyl benzoin ether. The proposed photocatalyst systems are
effective in reducing oxygen inhibition; however, they suffer from the deficiency
that the time required for cure in oxygen is longer than the time required to cure
- the same formulation in an inert environment. The increased cure cycle is
highly disadvantageous, because of its deleterious effect on many substrates,
30 such as warping and charring; and because it negatively a~fects productivity.Osborn et al, U. S. A. Paterk No. 3~ 759~ 807 disclose that the photopoly-
merization rate, that is, the cure rate, can be accelerated by employing combinations
;.' ,.
.. ..
~il3~6
of certain organic carboryl compounds, such as benzophenone, in combination
with certain organic amine cornpounds, such as triethanolamine. lIowever,
these photocatalyst systems are essentially ineffective in providing both bulk and
surface cure in oxygen-containing environments and, as with the Gruber systems,
5 the systems are significantly slower in oxygen-corltaining environments than in
inert atmospheres.
Continued research into the development of energy curable compositions
which can be cured by exposu:. e to actinic radiation in the presence of air hasresulted in the discovery that unsaturated oligomers, including unsaturated
10 urethane oligomers, derived from poly(alkylene oxide) polyols can be cured incombination with photocatalyst systems comprising, (I) at least one compound
which promotes free radical addition polymerization through birnolecular photo-
chemical reactions o~ the energy donor or transfer type, of the hydrogen ab-
straction type, or by formation o a donor-acceptor complex with monomers or
15 additives leading to ionic or radical species; or9 (II), at least one compound (I)
in combination with at least one compound which promotes free radical addition
polymerization by generating reactive specie, such as free radicals, by way of
unimolecular homolysis resulting from photoexcitation, by exposure to actinic
radiation in the presence of o~ygen in an unexpectedly short cure cycle. It was
20 also discovered that, (1), ultimate properties of the cured compositions can be
enhanced by incorporating into the curable compositions at least one chain
transfer agent and, (2), certain chain transfer agents are ef~ective in further in-
creasing rate of cure.
The present invention is based on the discovery that the nature of the
25 polyol which is employed in forming energy-curable unsaturated oligomers doesmaterially af~ect the curing rate in o~ygen of such oligomers. More particularly,
it has been discovered that the use of poly(alXylene oxide) polyhydroxy and poly-
- ethereste~ polyhydroxy and polycarboxy compounds which contain the residue
of at least one poly(alkylene o~ide) polyol integrated into the main chain or back-
30 bone of such polyetherester compounds as precursor materials for energy-curable
unsaturated oligomers affords compositions which can be cured in oxygen at
rates approaching those encountered when curing is effected in inert atmospheres.
The discovery was particularly unexpected because there is no significant difference
,
... . ... .. . . . . . . .
:~3~4~;
5 --
in the cure rate of unsaturated oligomers, regardless of the precursor materialsemployed in preparing such oligomers, when cure is effected in an inert
atmosphere.
Thus, in accordance with one aspect of the invention, there are provided
5 novel unsaturated urethane oligomers comprising the reacticn product of, (i),
at least one organic isocyanate compound having at least two isocya~ate groups;
(ii), at least one polyetherester polyol containing the residue of at least one poly-
(alkylene oxide~ polyol integrated into the backbone of such polyetherester polyol;
and, (iii), at least one unsaturated addition-polymerizable monomeric compound
10 having a single isocyanate-reactive active hydrogen group.
In a second aspect of the invention, there are provided novel energy
curable compositions comprising (a), unsaturated urethane oligomers comprising
the reaction product of (i), at least one organic isocyanate compound having ak
least two isocyanate groups; (ii), at least one polyetherester polyol containing15 the residue of at least one poly(alkylene oxide) polyol ~tegrated into the backbone
of such polyetherester polyol; and, (iii), at least one unsaturated addition-poly-
merizable monomeric compound having a single isocyanate-reactive active hydrogengroup; (b) at least one reactive monomer diluent; and, optionally, (c) a photo-
catalyst system selected from the group consisting of (1), at least one compound20 which promotes free radical addition polymerization through bimolecular photo-
chemical reactions of the energy donor or transfer type, of the hydrogen ab-
straction type, or by the forma~ion of a donor-acceptor complex with monomers
or additives leading to ionic or radical species; and (II) an admixture comprising,
(i), at least one photocatalyst system (I) compound in association with, (ii) at- 25 least one compound which promotes free radical addition polymerization by gener~
ating reactive specie by way of unimolecular homolysis resulting from photo-
excitation; and, (d), also optionally, an effec~ive amount of at least one chain~
transfer agent; and, (e), also optionally, up to 75 percent by weight of at least
one unsaturated urethane oligomer derived from a non-poly(alkylene oxide~
30 polyol precursor~ said weight percent being based on total weight of (a) and (e).
In still another aspect of the invention, there are provided novel energy~
curable compositions comprising
L3~46
- 6 -
I) at least one unsaturated oligomer selected from the group con-
sisting of
A) the reaction product of
i) at least one olefinically unsaturated compound containing
a single carboxylic acid group; and
ii) at least one poly(alkylene oxide) polyol;
B) the reaction product of
i) at least one olefinically unsaturated compouncl containing
a single carboxylic acid group; and
ii) at least one polyhydroxy polyetherester having at least two
hyd:roxyl groups, said polyhydroxy polyetherester having in its backbone or
main chain the residue of at least one poly(a~ylene oxide) polyol; and
C) the reaction product of
i) at least one olefinically unsaturated compound containing
a single carboxylic acid-reactive group; and
ii) at least one polycarboxy polyetherester having at least two
carboxylic acid groups, saidpolycarboxypolyetherester having in its backbone
or main chain the residue of at least one poly(alkylene oxide); and, optionally
and preferably,
II) at least one reactive monorner diluent; and, optionally and preferably~
IJI) a photocatalyst system selected from the group consisting of
A) at least one compound which promotes free radical addition poly-
merization through birrLolecular photochemical reactions of the energy donor or
transfer type, of the hydrogen abstraction type, or by the formation of a donor-acceptor complex with monomers or additives leading to ionic or radical species;and
B) an admixture comprising
i) at least one compound which promotes free radical addition
polymerization through bimolecular photochemical reactions of the energy donor
or transfer type, of the hydrogen abstraction type, or by the formation of a
donor-acceptor complex with monomers or additives leading to ionic or radical
species; in association with
. ~ ,
... . ... .. . . .
3~
-- 7 --
ii) at least one compound which promotes free radical addition
polymerization by generating reactive specie by way of unimolecular homolysis;
and, optionally,
IV) an effective amount of at least one chain transfer agent; and,
5 optionally
V) up to 75 percent by weight of at least one unsaturated oligomer
derived from non-poly(alkylene oxide) polyol precursor compounds, said weight
percent being based on total weight of (I) and (V).
Additionally, the invention provides a process for coating a substrate
10 which comprises applying to a surface of the substrate the energy-curable
compositions of this invention and exposing such coated substrate to actinic
radiation in the presence of oxygen whereby the coatiny is cured into a hard,
mar- and abrasion-resistant film. The invention also contemplates articles of
manufacture cornprising a substrate having a desired geornetrical configuration
15 and size having thereon a cured wear coating, said coating being formulated,
applied and cured according to the concepts of the herein-described invention.
The novel unsaturated oligomers of the present invention are charac-
terized by the presence of at least one ethylenically unsaturated group having
the structure - CH = C , preferably having the structure CH2 = C = , said
20 group preferably being terminally located; and having a main chain or backbone
containing the residue of at least one poly(alkylene oxide) polyol, said main
chain being separated from said ethylenically unsaturated group by at least one
ester group or at least two urethane groups, as the case may be. Such unsaturated
oligomers comprise
I) the reaction product of
A) at least one olefinically unsaturated compound having a single
reactive moiety selected from the group consisting of carboxyl and hydroxyl;
- and
B) at least one organic compound having in its rnain chain a unit
30 having the structure (YO )n; wherein Y is a hydrocarbon chain having at leastone carbon atorn and which can be interrupted by one or more ether oxygen atoms;n is at least two; said organic compound having at least two hydro~yl groups or
two carboxyl groups; said orga~ic compound being selected from the group
-
3~
consisting of
1 ) poly(alkylene oxide) polyhydroxy compounds;
2) polyetherester polyhydroxy compounds; and
3) polyetherester polycarboxy compounds;
said polyetherester compounds (1) and (2) comprising the
reaction product of
i) from 3 to 100, preferably 40 to 100, mol percent of at
least one poly(alkylene oxide) polyol having at least two hydroxyl groups;
ii) from 97 to zero, preferably 60 to ze.ro;
iii) from 97 to zero, preferably 60 to zero, mol percent of
at least one monomeric polyol having at least two hydroxyl groups; and
iv) from 97 to zero, preferably 60 to zero, mol percent of
at least one polyester which does not contain poly(alkylene oxide) polyol residues
in its backbone;
said mol percents being based on total mols of precursor
materials (i) - (iv), inclusively; and
v) at least one polycarboxylic acid characteri~ed by the
presence of at least two carboxyl groups, including anhydrides of such acids;
and
II) the reaction product of
A) at least one organic isocyanate compound having at least tw
isocyanate groups;
B) at least one polyetherester polyol having at least two hydro~yl
groups~ said polyetherester polyol comprising the reaction product of
2~ . 1) from 3 to 100, preferably 40 to 100 mol percerlt of at least
one poly(alkylene oxide) polyol having at least two hydroxyl groups;
2) from 97 to zero mol percent of at least one polymeric non-
poly(alkylene oxide) polyol having at least two hydroxyl groups;
3) from 97 to æero mol percent of at least one monomeric polyol
having at least two hydroxyl groups; and
4) from 97 to zero mol percent of at least one pol-yester which
does not contain poly(alkylene oxide) polyol residues in its backbone;
said mol percents being based on total mols of precursor
.... ,~................. o
1~L3~4
materials (B)(l) - ~B)(4), inclusively; and
5) at least one organic polycarboxylic acid characterized by the
presence of at least two carboxyl groups; and
C) at least one unsaturated addition-polymerizable monomeric
5 compound having a single isocyanate-reactive active hydrogen group;
there being present an excess of isocyanat~ compound with
respect to the hydroxyl gxoups of said polyetherester polyol;
said unsaturated addition-polymerizable compound having a
single isocyanate-reactive active hydrogen group being present in an amount
10 sufficient to provide at least one rnolar equivalent of active hydrogen group with
respect to isocyanate reactivity. The invention contemplates unsaturated oligomers
having at least one olefinically unsaturated moiety and residual hydroxyl, carboxyl
or isocyanate functionality, as well as oleEinically unsaturated oligomers having
substantially no residual hydroxyl, carboxyl or isocyanate functionality, with
15 the latter fully-capped olefinically unsaturated oligomers being especially prefer-
red. An expecially preferred class of unsaturated oligomers are the acrylated
oligorners, including acrylated urethane oligomers, that is, oligorners which
have been rnodified by incolrporating into the oligomeric molecule one or more
acrylic groups having the structure
CH2 = C - C - O -;
X O
wher~in X is hydrogen, halogen, an alkyl group having from 1 to 8 carbon atoms
and ClI2 = C -, wherein X is as previously defined.
The poly(alkylene oxide~ polyols having at least two hydroxyl groups
which are essential to the present invention are normally obtained from the
25 polymerization, including block copolyrnerization, of cyclic ethers such as
alkylene oxides, dioxolane and tetrahydrofuran, the condensation of glycols, or
the condensation of cyclic ethers with glycols. They are well-known articles of
comrnerce, and are also called polyalkylene ether glycols7 polyalkylene glycols,polyaLkylene oxide glycols, polyglycols and polyoxyalkylene glycols. They may
'
.. . .. . . .
~3~4~i;
- 10 -
be represented by the formula HO(RO)n H, in which R i5 an alkylene radical
and n is at least 2. The alkylene radical can be a single chain or can consist
of two or more alkylene chains separated from each other by an ether o~ygen
atom. Preferred poly(alkylene oxide) polyols have fro n 1 to 9, preferably 1 to
5 8 carbon atoms and have a number average molecular weight in the range fro~
about 250 to about ~aoo, preferably about 250 to about 2500. Not all the a~kylene
units need be the same. Poly(alkylene oxide) polyols forrned by the copoly-
merlzation or condensation of mixtures OI different cyclic ethers, glycols, or
glycols and cyclic ethers can be used; as can poly(alkylene oxide) polyol
10 derived from cyclic ethers such as dioxocane, which affords a polyol having the
formula HO(CH2-0-CH2-CH2)n E, where n is greater than 1. The alkylene can
be a straight or a branched chain, as in poly(propylene oxide) polyol. In the
case where the alkylene unit is ethylene, it can be advantageous to incorporate
the unit into a copolymer, Eor example. As a copolymer of ethylene o~ide and
15 propoylene oxide, with up to 80 percent of such copolymer comprising ethyleneoxide. Representative poly(alkylene oxide) polyols include poly(ethylene oxide)
polyols, poly(propylene oxide) polyols, poly(tetramethylene oxide) polyols, poly(nonamethylene oxide) polyols, poly(oxymethylene-ethylene oxide copolymer)
polyols, and poly(pentaerythritolethylene oxide) polyols. Thus the poly(alkylene20 oxide) polyols will generally have from 2 to 6 hydroxyl groups, with such polyols
having 2 hydroxyl groups being currently preferred. Preferred poly(alkylene
oxide) polyols are poly(tetramethylene oxide) polyols, poly(propylene oxide)
polyols, poly(ethylene oxide-propylene oxide) polyols, and poly~ethylene oxide)
polyols, including diethylene glycol, poly(aL'{ylene oxide) polyol wherein n is 2,
25 with poly(ethylene oxide) polyols being currently especially preferred.
Another useful group of poly~alkylene oxide) polyols which ca~ be
employed in the practice OI the invention are poly(alkylene ether-thioether) com-
pounds, which compounds have the identical formula as the poly(alkylene oxide)
polyols except that some of the ether oxygens have been replaced with sulfur
30 atoms. Such polyols are conveniently prepared by the reaction of a compound
such as thiodiglycol with ethylene glycol in the presence of a catalytic amount
amount of p-toluene sulfonic acid. Other polyethers, such as poly~alkylene oxide-
arylene ether) polyols may be used.
.... . .
4~ii
11 -
It is essential that the polyetherester polyhydroxy and polycarboxy
compounds which are utilized to form unsaturated oligorners, including unsaturated
urethane oligomers, in accordance with the invention have, as an i~tegral paxt
of the backbone or main polyrneric chain, the residue of at least one poly-
5 (alkylene oxide) polyol, that is, the poly(a~ylene oxide~ recurring unit of thestructure ~ YO ~n, in the main chain, said recurring unit being the residue
of at least one poly(alkylene oxide) polyol, n is at ]east 2, and Y is a hydro-
carbon chain which can be interrupted by one or more ether oxygen atoms. As
noted the polyetherester can be, and is pre:Eerably, derived ~rom poly(alkylene
10 oxide) polyols having at least two hydroxyl groups or can contain up to 97 mol
percent of at least one non-poly(aLkylene oxide) polyol monomeric polyol or
polymeric polyhydroxy or polycarboxy compound having at least two hydroxy or
carboxy groups, said mol percent being based on total mols ~f poly(alkylene oxide)
polyol and non-poly(alkylene oxide) polyol rnaterials.
Substantially any of the known monomeric alcohols having at least two
hydroxyl groups, polyrnerlc non-poly(alkylene oxide) polyol materials having at
least two hydroxyl or carboxyl groups, and polyesters having at least two
hydroxyl or carboxyl groups but which do not contain poly(a~ylene oxide) polyol
residues in the backbone or rnain chain can be employed in combination with
poly~alkylene oxide) polyols to form the polyhydroxy and polycarboxy polyether-
ester compounds which serve as precursor materials for the unsaturated
oligomers of this invention. Representative monomeric and polymeric polyhydroxy
and polymeric polycarboxy compounds which can optionally provide up to about
9'7 mol percent with respect to the composition of the polyetherester starting
materials include 1, 4-butane diol; 1, 3-butylene glycol; 1, 6-hexane diol; 1, 4-
cyclohexane diol; 4, 4'-methylene-bis-(cyclohexynol); glycerol; trimethylolpropane;
1, 2, 6-hexanetriol; erythritol; pentaerythritol; neopentyl glycol; polycaprolactone
diols and triols; poly~butadiene) diols and dicarboxylic acids, hydroxylate poly-
(butadiene) diols and diacids; poly(tetramethylene adipate) diols and diacids;
poly(ethylene succinate) diols and diacids; poly(l, 3 butylene sebacate) diols and
diacids; and (17 3-butylene glycol/glycerine/adipic acid/isophthalic acid) poly-hydroxy materials and the corresponding polycarboxy materials. Migtures of
~3~4
- 12 -
such monomeric and polymeric compounds can be employed.
Polycarboxylic acids which may be employed in forming the polyhydroxy
and polycarboxy polyetherester materials which are utilized in the present
invention consist primarily of monomeric carboxyLic acids having at least two
carboxyl groups or their anhydrides having from 2 to 14 carbon atoms per molecule,
with dicarboxylic acids or their anhydrides being currently preferred. Among
such useful acids are phthalic acid, isophthalic acid, tel ephthalic acid, tetra-
hydrophthalic acid, hexahydrophthalic acid, adipic acid, sebacic acid, maleic
acid, glutaric acid, chlorendic acid, tetrachlorophthalic acid, itaconic acid,
trimellitic acid, tricarballylic acid, and other known polycarobxylic acids of
varying type. It is currently preferred that the polyethester include an aliphatic
dicarboxylic acid as at least part oE the acid cornponent.
The isocyanate compounds which are employed in formin~ the unsatur-
ated urethane oli~omers in accordance with the present invention can be any
organic isocyanate compound having at least two free isocyanate groups. In-
cluded within the purview of suitable polyisocyanates are aliphatic, cycloaliphatic,
and aromatic polyisocyanates, as these terms are generally interpreted in the
art. Thus it will be appreciated that any of the known polyisocyanates such as
alkyl and alkylene polyisocyanates, cycloalkyl and cycloaLkylene polyisocyanates,
aryl and arylene polyisocyanates, and combinations such as alkylene, cycloaLkylene
and alkylene arylene polyisocyanates, ca~ be employed in the practice of the
present invention.
Suitable polyisocyanates include, without limitation, tolylene-2, 4-
diisocyanate, 2, 2, 4-trimethylhexamethylene-1, 6-diisocyanate, hexamethylene-l,6-diis~cyanate, diphenylmethane-4, 4'-diisocyanate, triphenylmethane-4, 4', 4"-
triisocyanate, polymethylene polyphenylisocyanate, m-phenylene diisocyanate,
p phenylene diisocyanate, 2, 6-tolylene diisocyanate, 1, 5-naphthalene diisocyanate,
naphthalene-l, 4-diisocyanate, diphenylene-4, 4'-diisocyanate, 3, 3'-bi-tolylene~
4,4'~diisocyanate, 1, 4-cyclohexylene dimethylene diisocyanate, xylylene-
1, 4-diisocyanate, xylylene-l, 3-diisocyanate, cyclohexyl-l, 4-diisocyanate,
4, 4' methylene-bis(cyclohexyl isocyanate), 3, 3'-dhnethyldiphenylmethane-
4, 4'-diisocyanate, isophorone diisocyanate, the product obtained by reacting
trimethylol propane and 2, 4-tolylene diisocyanate in a ratio of 1:3, and the like.
~3
- 13
The diisocyallate compounds are preferred, with 4, 4' methylene-bis~cyclohexyl
isocyanate) being especially preferred.
Ethylenically unsaturate carboxylic acids which are reacted with the
above-described polyhydroxy poly(alkylene oxide) and polyhydroxy-polyether-
5 ester compounds include acrylic acid~ methacrylic acid, crotonic acid, alpha-
phenylacrylic acid, cyanoacrylic acid, me-thoxy acrylic acid, alpha-cyclo-
hexylacrylic acid, and the like. There can also be used the unsaturated partial
esters OI unsaturated and saturated aliphatic, cycloaliphatic and aromatic poly-carboxylic acids which are monobasic in nature, that is, the polycarboxylic
10 partial ester has only one free reactive carboxyl group, which group is
available for reaction with the hydroxyl groups of the poly(alkylene oxide) polyol
and the polyhydroxy polyether ester. Such partial esters are readily formed
by reacting polycarboxylic acids such as adipic acid, -fumaric acid, maleix acid,
alpha-chloromaleic acid, succinic acid, terephthalic acid, te-trahydroterephthalic
~5 acid and the like with an unsaturated monofunctional compound such as 2-hydroxy-
0thyl acrylate, 2-hydroxyethyl methacrylate, the corresponding thiols and allyl
alcohol and the like under conditions such that all carboxyl groups but one are
esterified. Currently, the unsaturated aliphatic monocarboxylic acids having from-
3 to lO carbon atoms are preferred, particularly acrylic and methacrylic acids.
20 It is understood that mixtures OI carboxylic acids can be employed.
Substantially any known compound which has at least one polymerizable
ethylenically unsaturated linkage or molety and a single reactive hydroxyl groupcan be employed as a reactant with the herein-described carboxyl-terminated
polyetheresters to form unsaturated oligomers suitable for use in the present
25 invention. A particularly preferred class of such compounds are the hydroxyalkyl
esters of acrylic and methacrylic acids representative of which are 2-hydro~y-
ethyl acrylate, 2-hydroxy~thyl methacrylate, 2-hydroxypropyl acrylate, 2-
hydroxypropyl methacrylate, diethylene glycol acrylate7 diethylene glycol
methacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, 3-chloro~
30 2-hydroxypropylacrylate, 3-chloro 2-hydroxypropyl methacrylate, trimethylol-
propane acrylate, trimethylolpropane dimethacrylate, pentaerythritol tri-
acrylate and pentaertyhritol trimethacrylate~ Also useful are the diol esters ofother lmsaturated acids, particularly alpha, beta-olefinically unsaturated acids,
~L~.31~
- 14 -
including crotonic acid, tiglic acid, and undecylenLc acid. The hydroxy-functional
partial esters of diols and half-esters of dicarboxylic acids are also useful.
Representative of these partial esters are 2-hydroxypropyl ethyl ~umarate, 2-
hydroxypropyl methyl itaconate, 2-hydroxyethyl fumarate diethylene glycol ethyl
5 mal ate. Other unsaturated dicarcaboxylic acids whose half esters can be
employed include, without limitation thereto, angelic acid, cirmamic acid,
aconitic acid, citraconic acid, mesaconic and glutaconic acid. Another useful
class of such ethylenically unsaturated compounds are unsaturated alcohols such
as allyl alcohol, methallyl alcohol, methyl vinyl carbinol, betaallyloxyethanol,10 para-allylbenzyl alcohol, crotyl alcohol, and unsaturated phenols such as ~-,meta-, or para-hydroxys~yrene and ortho- or para-allyl phenol. Other useful
ethylenically unsaturated monohydroxy compounds which are equivalent to those
herein recited will be readily apparent to the person of ordinary skill in the art.
Unsaturated addition-polymerizable monomeric organic compounds having
15 a single isocyanate-reactive hydrogen group which can be employed in the practice
of the present invention include any of such compounds which have been previously
used to introduce an unsaturated polymeri~able moiety into a molecule via
reaction between the active hydrogen group and a reactive isocyanate moiety.
Preferably, the active hydrogen group is hydroxy. Illustrative of unsaturated
20 addition-polymerizable monomeric organic compounds having a single iso-
cyanate-reactive active hydrogen group are 2 hydroxyethyl acrylate, 2-hydroxy-
ethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl rnethacrylate,
N-hydroxymethyl acrylamide, N-hydroxymethyl methacrylamide, diethylene
glycol monoacrylate, diethylene glycol monomethacrylate~ glycerine dimeth-
25 acrylate, trimethylol propane dimethacrylate, and the like. The amount of suchcompounds will be sufficie~t to provide at least one molar equivalent of activehydrogen group with respect to isocyanate functionality, and preferably is suf-
ficient to a~ford an active hydrogen group; NCO ratio, wlth respect to the amount
of total free hydroxyl functions, of at least 1:1, with a small excess,l0 rnol
30 percent or less, being especially preferred.
The polyetherester precursor materials for the unsatura~ed oligomers,
including unsaturated urethane oligomers, of the invention are prepared by con-
ventional esterification techniques employLng conventional apparatus.
.~ 3~9
- 15 -
Esterification is generally effected in the presence of an inert atmosphere
such as nitrogen. The poly(alkylene oxide) polyol and non-(polyalkylene oxide)
polyol monomeric and polymeric materials are mixed in a suitable reactor and
heater with agitation to from 60 C to 100 C or higher. The acid components
are then added and heating with agitation continued at a temperature and rate
such that the water of esterification can be rapidly rernoved, generally by
distillation. When producing hydroxy-functional polyetherester materials, the
esterification reaction is continued until the acid number is 10 or less and sub-
stantially all of the water of esterificat~on and low-boiling impurities are re-moved. In the case of carboxy-function~polyetherester materials, the ester-
ification reaction is terminated when there is reached an acid number cor-
responding to the desired equivalent weight of the resulting carboxy-functional
polyetherester. The reaction proceeds smoothly with heating. If desired,
esterification catalysts such as tertiary amines and organometallic compounds
can be employed.
The unsaturated oligomers which form the basis of the novel compositions
of the invention are conveniently obtained by reacting~ (1), at least one poly
(alkylene oxide) polyol or polyhydroxy polyetherester, including mixtures there-of, and at least one compound containing at least one polymerizable ethylenically
unsaturated moiety and a single reactive carboxyl group; and, (2), at least
one polycarboxy polyetherester and at least one compound containing at least
one polymerizable ethylenically unsaturated moiety and a single reactive hydroxyl
group; under well-known esterifying conditions, for example, at a temperature
in the range from 70 - 250 C for 3 to 20 hours, in the presence or absence of
an esterification catalyst such as sulfuric acid, para-toluene sulfonic acid andmethane sulfonic acid to result in esterification of the hydrogy groups with
carboxyl groups. Preferably, the hydroxy- and carboxy-containing materials
will be used in amounts su~icient to o~tain a completely esterified unsaturated
oligomer.
The novel unsaturated urethane oligomers can be prepared by any of
several known reaction routes, including (1) simultaneous reaction of poly-
isocyanate, polyetherester polyol and unsaturated addition-polyrnerizable
monomeric compound having a single isocya~ate-reactive active hydrogerl group;
1~3094i j
- 16 -
and (2) reaction of polyisocyanate and unsaturated addition-polyrnerizable monomeric
compound having a single isocyanate-reactive active hydrogen group to form
an unsaturated isocyanate-functional compound which is then reacted with the
polyetherester polyol, the amount of unsaturated isocyanate being sufficient
to consume all hydroxyl groups of the polyol with excess isocyanate functions being
preferably reacted with additional unsaturated polymerizable monomeric compound.The preferred method of forming the herein described oligomers is, (3) a two-
step process comprising, (I ), contacting polyetherester polyol with sufficient
polyisocyanate to form a~ isocyanate-functional urethane prepolymer, and, (II),
contacting such urethane prepolymer with unsaturated addition-polymerizable
monomeric organic compound having a single isocyanate-reactive active hydrogen
group to produce the desired oligomer having at least one unit of ethylenic un-
saturation per molecule, with acrylated urethane oligomers, especially acrylatedurethane oligomers having substantially no free isocyanate functionality, being
especiallypreferred. In formingthe herein described oligomers, there willbe
eraployed at least a slight excess of polyisocyanate with respect to the hydroxyl
functions of the polyol. Preferably, the amount of polyisocyanate will be suf-
ficient to provide an NCO:OH ratio, with respect to the hydroxyl groups of the
poly(alkylene oxide ether) polyol, of at least 2.1:1, preferably at least 2.3:1,and especially at least 2. 5:1, with an NCO:OH ratio in the range of about 2. 5-5:1 being particularly preferred. The oligomers of this invention can be prepared
neat, as can the intermediates in the multi-step processes, but are preferably
perpared in the presence of a diluent phase which is copolymerizable with the
unsaturated urethane oligomer but is otherwise inert during the particular
process of preparing the oligomers. Because the various methods of preparing
unsaturated urethane resins are well-known, for example, see U. S. Patent
No. 3, 700, B43, it is considered that any detailed discussion of such methods
is unnecessary.
The unsaturated oligomers, including unsaturated urethane oligomers
prepared according to the concepts of this invention are readily cured when
combined with the described photocatalyst systems when exposed to actinic
radiation in the presence of oxygen. Preferably, the unsaturated oligomers are
admixed with a reactive diluent system as described in more detail hereinafter.
.~
..... ,, .. .. , ..... , . .. , - - ~
0~
- 17 -
The energy-curable compositions of this invention can optionally contain an
effective amount of at least one chain transfer agent, and, also optionally, up
to about 75 percent by weight, based on total resin solids, of at least one other
unsaturated oligomer, preferably at least one unsaturated urethane oligomer,
5 especially at least one acrylated urethane oligomer, which other unsaturated
oligomer does not contain any poly(alkylene ether~ polyol residues in its main
chain.
Reactive diluent systerns which can be employed in the energy curable
compositions of this invention include any of such systems which have been or
10 are being used for this purpose. Broadly, suitable reactive diluent systems
comprise at least one unsaturated addition-polymerizable monomeric compound
which is copolymerizable with the unsaturated urethane oligomer upon exposure
to acting radiation. The reactive diluent can be monofunctional or polyfunctional,
with respect to polymerizable moieties. A single polyfunctional reactive diluent15 can be used, as can rnixtures thereof; or a combination of one or more mono-
functional reactive diluents and one or more polyfunctional reactive diluents
can be used. Such combinations of mono- and polyfunctional reactive diluents
are presently preferred. Generally, the reactive diluent system will comprise
from about 10 to about 65, preferably about 15 to about 50, weight percent,
20 based on total weight of unsaturated urethane oligomer and reactive diluent, of
the energy curable compositions of the invention. Particularly preferred r eactive
diluents are unsaturated addition-polymerizable monofunctional monomeric
compounds selected from the group consisting of esters having the general
formula
o
CH2 = C - C - O - R,
R
wherein R is hydrogen or methyl, and R is an aliphatic or cycloaliphatic group
having from 4 to 18 carbon atoms. Representative of such preferred reactive
monomeric diluents, without limitation thereto, are hexyl acrylate, cyclohexyl
acrylate, 2-ethylhexyl acrylate octyl acrylate, nonyl acrylate, stearyl acrylate,
30 and the corresponding methacrylates. Illustrative of other reactive monofu~ctional
1~30~3~6
- 18 -
and polyfunctional monomeric diluents which can be employed are styrene,
methyl methacxylate, butyl acrylate, isobutyl acrylate, 2-phenoxy acrylate,
2-methoxyethyl acrylate, 2-~N, N-diethylamino)-ethyl acrylate, the correspondingmethacrylates, acrylonitrile, methyl acrylonitrile" methacrylamide, neopentyl
5 glycol diacrylate, ethylene glycol diacrylate, hexyLene glycol diacrylate,
diethylene glycol diacrylate, trimethylol propane triacrylate, pentaerythritol
di-" tri-, or tetra-acrylate, the corresponding methacrylates, vinyl pyrrolidone~
and the like. At the present time, it is preferred that the reactive diluent system
contain at least one acrylic and/or methacrylic acid ester having at least 6
10 carbon atoms in the non-acid moiety, with such acrylic acid esters being prefer-
red. Reactive diluent systems are well-known to those skilled in the art of
radiation curing and the selection of an appropriate diluent system in any giveninstance is suEf~ciently encompassed by such knowledge as to require no furth0r
discussion here.
When curing is effected in the presence of oxygen by exposure to actinic
radiation, the energy-curable compositions of the present invention must have
incorporated therein an effective amount of a photocatalyst system selected
from the group consisting of, (I), at least one compound which promotes free
radical addition polymerization through bimolecular photochemical reactions of
20 the energy donor or transfer type, of the hydrogen abstraction type, or by the
formation of a donor-acceptor complex with monomers or additives leading to
ionic or radical species or, (II), at least one compound which promotes free
radical addition polymerization through bimolecular photochemical reactions of
the energy donor or transfer type, of the hydrogen abstraction type, or by the
25 forrnation of a donor-acceptor complex with monomers or additives leading to
ionic or radical species in combination with at least one compound which
promotes free radical addition polymerization by generating a radical pair by
way of unimolecular homolysis resulting from photoe~citation.
Compounds (1) which are effective to promote free raclical addition
30 polymerization through bimolecular photochemical reactions of the energy
donor or transfer type of hydrogen abstraction type of by formation of a
donor-acceptor complex with monomers or additives leading to ior~ic or radical
spacies are well-known, as are compounds (2) which are effective to promote
.. . .....
~3~
- 19 -
free radical add tion polymerization by generating reactive specie, such as
free radicals, by way of unimolecular scission resulting from photoexcitation.
Such compounds (1) and (2) are described as photosensitizers and photoinitiators,
respectively, by at least one patentee, see Gruber U. S. Patent No. 4, 017, 652
and, for the purpose of establishing sorne measure of consistency with respect
to nomenclature, that description will be followed herein, With respect to
photopolymerization processes, photosensitizers are not good initiators per
se, but do readily absorb protons to produce an excited molecule which then
acts through energy transfer, hydrogen abstraction or formation of a donor-
acceptor complex with a second molecule to produce free radicals which are
capable of initiating additional polymerization reactions. Unlike the photo-
sensitizers which form free radicals through interaction with a second molecule,photoinitiators absorb protons to produce an excited molecule which can cleave
to produce ree radicals which are capable of initiating addition polymerizationreactions.
Particularly preferred photosensitizers are aroraatic ketones and aro-
matic aldehydes which can exist in a triplet st~te, especially such ketones and
aldehydes which have a triplet energy in the range from 35 to 85, preferably
42 to 72, kilocalories per mole. Such photosensitizers are described in Gruber
U.S. Patent No. 4, 017, 652 and Osborn et al U.S. Patent No. 3, 759, 807,
Currently,
benzophenone, benzil, 4, 4'-dichlorobenzophenone, 4-methocy-benzophenone and
dibenzosubsrone are preferred.
Photoinitiators are preferably selected from compounds having the
formula
O
1. ~--C - C - R2
R3
wherein R1, R2 and R3 are independently hydrogen, hydroxyl,
halogen, alkyl of 1 to 12, preferably 1 to 8, carbon atoms7 alkoxy of 1 to 12,
preferably 1 to 8, carbon atoms, or phenyl, providin~ that R1, R2 and R3 are
,~
3094
- 20 -
not concurrently all hydroge~ hydroxyl, halogen7 or alkyl; and wherein at
least one of Rl, R2 or R3 is preferably hydroxyl or alkoxy. The alkyl,
alkoxy and phenyl groups can be substituted with moieties which will not
interfere with the function of the compound as a photoinitiator. Representati~Te5 substituent moieties or groups include halogen, alkyl of 1 to 8 carbon atoms,
alkoxy having from 1 to 8 carbon atoms in the alkyl group, carboxy and carW
balkoxy having from 1 to 8 carbon atoms in the alkyl groups. Photoinitiators
in which the alkyl, alkoxy and phenyl groups are unsubstituted are preferred.
A second class of preferred photoinitiators has the formula
O O
R4~3 C - C' - oR5,
wherein R4 is hydrogen, halogen, alkoxy containing from 1
to 8, preferably 1 to 4, carbon atoms or alkyl containing from 1 to 8, preferably
1 to 4 carbon atoms; and R5 is hydrogen, alkyl containing from 1 to 22 carbon
atoms, benxyl, phenyl, hydroxyalkyl containing from 1 to 12 carbon atoms,
15 haloalkyl containing frorn 1 to 12 carbon atoms, alkoxyalkyl wherein the alkoxy
portion contains from 1 to 8 carbon atoms and the alkyl portion contains from
1 to 12 carbon atoms, and phenoxyalkyl wherein the alkyl portion contains i~rom
1 to 12 carbon atoms, R4 being preferably hydrogen, alkyl OI 1 to 12 carbon
atoms, benxyl or phenyl.
Particularly preferred photoinitiator compounds are represented by
the formulae
... .. . . . . . . . . . .
1~3~9
21
o o o
~- C - C~ - R6,(~_ C - CHz- R6,(~ 1 6
O oR7 O
(~- C - C _ ~8 <~,- C - CH ~,
OR oR7
wherein R6 is halo~en; R7 is an alkyl group having from 1 to
12, preferably 1 to 8, carbon atoms; and R8 is hydrogen, aL{yl of 1 to 12 carbon5 atoms, aryl of 6 to 14 ring carbon atoms, and cycloalkyl of 5 to 8 ring carbonatoms. Where a plurality of R6 or R7 groups are found on the rnolecule, they
ca~ be the same or different.
The photoinitiators which are ernployed in combination with the hereto-
fore described photosensitizers in the practice of the invention are well-~mown
10 articles of commerce. A representative listing of such compounds can be found-
in U. S. Patent No. 4, 017, 652, column 4, lines 46-63; U. S Patent No.
4, 024, 296, column 4, lines 18-37; and U. S. Patent No. 3, 715, 293, column 1,
line 4,1 through column 2, line 13.
Presently preferred photocatalyst systems comprise admixtures of,
15 (a), benzophenone and benzoin isobutyl ether, and, (b), benzophenone and 2,2- diethoxyacetophenone.
It has also been found that the inclusion of chain I:ransfer agents in the
energy-curable compositions employed in the practice of this invention can
beneficially affect ultimate cured film properties. Substantially a~y of the
20 known chain transfer agents ca~ be so employed. Generally, such compounds,
when utilized, will be employed at levels not exceeding about 15 parts by
weight, per 100 parts of combined weight of unsaturated urethane oligomer
- and reactive diluent, and preferably will be employed in the range ~orn about
... .. ...
--
~30946
- 22 -
0.1 to about 5 parts by weight. Representative chain transfer agents for ad-
dition polymerization reactions include benzene; toluene; ethylbenzene, iso-
propylbenzene; ;~-butylbenzene; cyclohexane; heptane; n-butyl chloride; n-
butyl bromide; n-butyl iodine; n-butyl alcohol; n-butyl disulflde; acetone;
5 acetic acid; chloroform; carbon tetrachloride; carbon tetrabromide; butylami~le;
triethylamine; ~-butyl mercaptan; n-butyl mercaptan; tertiary aliphatic amines
such as triethanolamine andk-butyl diethanolamine; 2-ethylhexane-1, 3-
dithiol; 1,10-decanedithiol' 1, 2-ethanedithiol; 1, 3-propanedithiol' 1, 6-
octanedithiol; 1, 8-octanedithiol; 1,10-octadecanedithiol; rn-benzenedithiol;
10 bis-(2-mercaptoethyl) sulfide; p-xylylenedithiol; pentaerythritol tetra-7-
mercaptoheptanoate; mercaptoacetic acid triglyceride; penthanethiol; dodecano
thiol; glycol mercaptoacetate; ethyl mercaptoacetate; and esters of thioglycolicand mercaptopropionic acids. :@referred chain transfer agents include both
monothiols and polythils; the polythioly having a molecular woight in the range
from about 95 to about 20, 000 and having the general formula
R9 (SH)rn~
wherein R9 is polyvalent organic moiety and m is at least 2,
being especially preferred. Particularly preferred polythiols include glycerol
trithioglycolate; pentaerythritol tetrathioglycolate; pentaerythritol tetrakis
20 (~ -mercaptopropionate); trimethylolpropane tris(thioglycolate); trimethylol-propane tris(,~ -m~rcaptopropionate); ethylene glycol bis(thioglycolate);
ethylene glycol bis(~ -mercaptopropionate) and poly(propylene oxide ether)
glycol bis(~B -mercaptopropionate).
As noted, unsaturated oligomers which do not contain any poly(alkylene
25 oxide) polyol residues in the main chain can be blerl~ed with the unsaturatedoligomers of the present invention. In such cases, the coatin~ compositions
should contain at least about 25 percent by total weight of combined unsaturatedoligomers of at least one poly(alkylene oxide) polyol-based unsaturated oligomer.
Representative polyol precursors for such other unsaturated oligomers are
30 polyesters, including caprolactone polyol polyesters.
.. ... . . . . . .
~L3~ 6
23 -
Preferably, the coating compositions of the invention will also cor~ain
from about 0.1 to about 10 parts by weight~ per 100 parts combined weight of
acrylic urethane oligomer and reactive diluent, of acrylic acid.
The invention compositions can also include pigrnents, fillers, wetting
5 agents, ilatting agents, flow control agents, and other additives typically
present in coating compositions. In sorne applicatlons, the inclusion of minor
amounts of inert solvents can be advantageous. Such additive materials are
well-known to those skilled in the art and do not require further elaboration
herein. Also well-known are the concentrations at which such additives are used.The coating compositions of this invention are prepared by conventional
methods such as blending. The compositions can be applied to wood, metal"
fabric and plastic substrates in an economic~al and eI~icient manner using
conventional industrial techniques and provide smooth, unifarm fikns which
are rapidly cured to dried films havlng e~cellent physical and chemical
15 properties. The compositions are particularly noteworthy in that they can be
cured in the presence of air at rates equivalent to those obtained in inert
atmospheres.
The improved coating compositions of this invention can be applied and
cured by any of the conventional known methods. Application can be by roll
20 coating, curtain coating, airless spray, dipping or by any other procedure.
The cure can be effected by exposure to any high energy source, such as
ionizing radiation, or low energy source, and are especia~ly suitable for curingby exposure to actinic radiation, such as ultraviolet light radiation, in the
presence of molecular oxygen. The equipment utilized for curing, as well as
25 the appropriate time for curing and the conditions under which the curing is
effected are well-known-to those skilled in the art of radiation curing and do
not require further elaboration herein.
The invention is illustrated in greater detail by the followirlg Examples~
but these examples are not be to construed as limiting the present invention.
30 All parts, percentages aMd the like are in parts by weight, unless otherwise
indicated.
3L:IL3~946
- 24 -
EXAl~PLE I
A reaction vessel equipped with stirrer, condenser, Dean Stark trap
and thermorneter is charged with 210 g trimethyloLpropane, 98 g neopentyl
glycol, 380 g adipic acid, 216 g isophthalic acid, 1. 4 g p-toluene sulfonic acid
and 258 g 1, 3-butylene glycol. The reaction ~ixture is heated at 243 C for
5 3 hours under nitrogen, during which tirne 134 ml water are removed.
To 600 g of the thus-prepared hydroxyl-terminated polyester, there
is added 173 g acrylic acid, 193 g mineral spirits and 4 g methane sulfonic
acid. The mixture is heated at 100 C under dry air for 10 hours, during which
time 44 ml water are removed in an axeotrope with mineral spirits. The
10 reaction product is stripped o~ solvent and cooled. There is obtained a clearviscous syrup of acrylated polyester oligorner which does not contain poly-
(alkylene oxide) polyol residues in the main chain.
EXA~IPLE II
:E?ollowing the procedure of Example I, 344 g adipic acid, 196 g iso-
phthalic acid, 158 g 1, 3-butylene glycol, 354 g tetraethylene glycol, and 178
g of trimethylolpropane are reacted to af Eord a hydroxy-functional polyetherester
containing poly(ethylene oxide) polyol residues in the rnain chain. The thus-
prepared polyhydroxy polyetherester (600 g), acrylic acid (149 g), methoxy-
hydroquinone (100 ppm), phenothiazine (100 ppm), and enough hexane to maintain
20 a reflux at 100 C are reacted to a~Eord a clear, viscous acrylated polyether-
ester oligorner containing poly(ethylene oxide) polyol residues in the main chain.
EXA~IPLE III
Following the procedure of Example I, 196 g polytetraethylene glycol,
150 g acrylic acid, 100 pprn methoxyhydroquinone, 100 ppm phenothiazine, 3. 6
25 g methane sulfonic acid and sufficient hexane to maintain a reflux at 100 C are
reacted for 14 hours at 100 C, during which time 36 ml water are removed.
-
- 25 -
The hexane is vacuum stripped from the reaction product. There is recovered
a clear, viscous syrup of acrylated polyether oligomer containing poly(ethylene
oxide) residues in the main chain.
EXAMPLE IV
To 100 parts by weight of each acrylated oligomer composition OI
Exa~nples I-III at 100% total resin solids, there are added 3 parts by weight
benzophenone and 1 part by weight benzoin butyl ether. The formulations are
coated onto aluminum panels, vinyl asbestos tile and vinyl sheet goods at a
1. 5 mil wet film thickness and cured in air using one 200 W/linear inch medium
pressure mercury vapor lamp at a transport speed of 100 feet/min. The
acrylated olig~omer composition of Example I requires 3 passes to obtain a
tack-free, mar-resistant surface finish whereas the acrylated oligomer com-
positions of Examples II and III each require only one pass to obtain the same
level of cure. At a transport speed of 200 feet/min., the acrylated oligomer
composition of Example I requires 5 passes to obtain a tack-free, rnar-resistantsurface finish, whereas the acrylated oligomer compositions of Exa~ples II
and m require only one pass to obtain the same level of cure.
Each acrylated oligomer composition is diluted to 80% resin solids
content in 2-ethylhexyl acrylate. To 100 parts by weight of each diluted com-
position there is added 4 parts of a 3:1 mixture of benzophenone and benzoin
butyl ether. The diluted compositions are coated onto alurninum panels, vinyl
asbestos tile and vinyl sheet goods and cured in air using one 200 W/linear
inch medium pressure mercury vapor larnp at transport speed of 100 feet/min.
Example I acrylated oligomer compositions require 5 passes to obtain a tack
frae~ mar-resistallt surface finish, whereas Example II and E~ample m
acrylated oligomer compositions require only 3 passes to obtain the sar~Le levelof cure.
.. . . . . .
L3~
- 26 -
EXAMPLE V
To 100 parts by weight of acrylated oligomer compositions (100% resin
solids content ~ of Example II are added 1~ 2 and 3 parts by weigrht of benzo-
phenone and benzoin isobutyl ether, individually. The compositions are coat:ed
5 onto aluminum panels at 1. 5 mil wet film thickness and cured in air followingthe procedure of Example IV at a transport speed of 100 ft. /sec. The number of
passes which are required to obtain a tack-free, mar-resistant surface finish
is as follows:
Photocatalyst System, PBW
Formulation BenzoPhenone Benzoin isobut~Tl ether Passes to cure
- 4
2 2
3 3 - 1
4 - 1 10
- 2 5
6 - 3 2
At a transport speed of 200 ft. /min., Formulation 3 containing benzo-
phenone alone requires 1 pass to obtain a tack-free, mar-resistant surface
while Formulation 6, which contains only benzoin isobutyl etherj requires 4
20 passes. The data demonstrate that cure in air is more effective with benzophe-
none alone than with benzoin isobutyl ether alone with unsaturated oligorners
containing poly(alkylene oxide) polyol residues.
EXAMPLE VI
Coating compositions are prepared from the acrylated oligomers
25 (100% resin solids content) of Examples I and II as follows:
... . . ... .. . . .
~_309L9~f6
- 27 -
Formulation 1 2 3 4 5
Example I oligomer 0 25 50 75 100
Example II oligomer100 75 50 25 0
Benzophenone 3 3 3 3 3
Benzoin isobutyl ether
The compositions are coated onto aluminum panels at 1. 5 mil wet
film thic~mess and cured in air according to the procedure of Egample IV
at a transport of 200 ft. /min. The number of passes which is required to
obtain a tack-free, mar-resistant surface finish is as follows:
Formulation Passes to cure
2 2
3 2
4 2
EXAMPLE VII
Following the procedure of Example I, 374 g adipic acid, 212 g isophthalic
acid, 312 g 1, 3-butylene glycol, 76 g tetraethylene glycol, 178 g trimethylol-
propane and 1. 2 g p-toluene sulfonic acid are reacted for 10 hrs., during whichtime 12~ ml water are removed. To 600 g of the resulting hydroxy~-functional
polyetherester containing poly(ethylene oxide) polyol residues in the main chainare added 149 g acrylic acid, 100 ppm methoxyhydroquinone, 100 ppm pheno-
thiazine, 3. 6 g methane sulfonic acid and sufficient hexane to maintain a
reflux at 100 C. The reaction proceeds for 8 hours, during which time 29 ml
water are removed. The hexane i5 vacuum-stripped from the reaction product
and there is obtained a clear viscous syrup (100% resin solids content) of
acrylated oligomer containing residues of poly(ethylene oxide) polyol in the
main chain.
To 100 parts by weight of the thus-prepared ac~ylated oligomer com
position are added 3 parts by weight benzophenone and 1 part by wei~ht benzoin
isobutyl ether. The formulation is coated onto aluminurn panels and cured in
air following the procedure of Example IV. Even though the oligorner contains
9~6
- 28 -
only 5% tetraethylene glycol, only 2 passes are required to obtain a tack-free,
mar-resistant surface finish compared to 3 passes which are required to obtain
the s~me level of cure with coating formulations prepared from the acrylated
oligomer of Example I, which does not contain any residues of poly(alkylene
5 oxide) polyols in the ~ain chainO
EXAMPLE VIII
Acrylated polyesters and polyetherester oligomer compositions at 100%
resin solids content are prepared as follows:
Acrylated polyester AP-VIII: A reaction vessel similar to that employed
in the procedure of Example I is charged with 317 g adipic acid, 40 g isophthalic
acid, 284 g 1, 3-butylene glycol and 46 g glycerine. The reaction mixture is
heated at 242 C for 8 hours, during which time 86 g water are removed. 509 g
g of the resulting hydroxyl-functional polyester containing no residues of poly-(alkylene oxide) polyol in its main chain, 190 g acrylic acid, 100 ppm methoxy-
hydroquinone, 100 ppm phenothiazine, 3. 6 g methane sul~onic acid and enough
hexane to maintain a reflux at 100 C are heated for 8 hours at 100 C under dryair. The contents of the reaction vessel are stripped of solvent and cooled.
There is obtained a clear viscous syrup of acrylated polyester oligomer (100%
resin solids content) containing no residues of poly(aLkylene oxide~ polyols in
20 its main chain.
Acr~,7lated pol Tetherester APR-VIll: Following the procedure employed
for the preparation of acrylated oligomer AP-~III, supra 313 g adipic acid,
228 g diethylene glycol and 136 g trimethylolpropane are reacted for 8 hours,
during which time 77 g water are removed. 508 g of the resulting hydroxyl-
25 terminated polyetherester containing residues of poly(ethylene oxide) polyol inits main chain, 192 g acrylic acid, 100 ppm methoxyhydroquinone, 100 ppm
phenothia~ine, 3. 6 g methane suLfonic acid and sufficient hexane to maintain a
reflux at 100 C are reacted for 8 hours at 100 C under dry air~ The hexane
is stripped from the reaction product. There is recovered a clear viscous
30 syrup (100% resin solids content~ of acrylated polyetherester oligomer having residues of poly(ethylene oxide) polyol in its main chain.
~L~L3~6
- 29 -
To 100 parts of each of AP-VIII- and APE-VIII acrylated oligomer
compositions there is added 3 parts benzophenone and 1 part benzoin isobutyl
ether. The formulations are coated onto aluminum panels at 1. 5 mil wet filrn
thickness and cured in air using one 200 in. /linear inch medium pressure
5 mercury vapor lamp at a transport speed of 100 ft . /min. Formulations
containing AP-VIII acrylated oligomer require 5 passes to obtain a tack-free,
mar-resistant surface finish. Formulations containi~g APE-vm acrylated
oligomer require only 3 passes to obtain a tack-free, mar-resistant surface
finish.
EX~PLE IX
Following the procedure of Example I, 438 g adipic acid and 212 g
diethylene glycol are reacted over an 8-hour period during which time 72 ml
H2O are removed to afford a carboxy functional polyetherester. The thus-
prepared polycarboxy functional polyetherester (578 g), hydroxyethylacrylate
(232 g), methoxyhydroquinone (100 ppm), phenothiazine (100 ppm), and enough
hexane to rnaintain a reflux at 100 C are reacted over a 5-hour period during
which time 36 ml of water are removed to afford a clear, viscous acrylated
polyetherester oligomer containing ether residues in the main chain.
EXAMPLE X
Following the procedure of Example I, 438 g adipic acid and 180 g 1, 3-
butylene glycol are reacted over an 8-hour period during which time 72 ml
H2O are removed to afford a carboxy functional polyester. The thus-prepared
polycarboxy functional polyester (546 g), hydroxyethyl acrylate (23w g),
methoxyhydroquinone (100 ppm), phenothiazene (100 ppm), and enough hexane
to maintain a reflux at 100 C are reacted over a 5-hour period during which
time 36 ml of water a~e removed to afford a clea~, viscous acrylated polyester
olîgomer without ether linkages in the rnain chain.
.. . . .
`` 1~L3~94~
- 30 -
EXAMPLE XI
To 100 parts of each acrylated oligomer composition of Exarnples
IX and X are added 3 paxts by weight benzophenone and 1 part by weight
benzoin butyl ether. The formulations are ~oated onto aluminum panels and
5 cured in air using one 200 W/linear inch medium pressure mercury vapor
lamp, at a transport speed of 100 ft. /min. The acrylated polyester of Example
IX, containing ether linkages, required two passes to obtain a tack-free, mar-
resistant surface while the acrylated polyester of Example X, without ether
linkages, required five passes to achieve the sa~ne degree of surface cure.
EXAMPLE XII
Following the procedure of Example I, 116 g maleic acid, 116 g of
hydro~y ethyl acrylate, 100 ppm rnethoxy hydroquinone, 100 ppm phenothiazene,
and enough hexane to maintain a reflu~ at 100 C are reacted while removing 18
ml of water to afford a mono-functional carboxylic acid with terminal acrylic
unsaturation. To the resultant product are added 98 g of tetraethylene glycol
and the reaction continued at 100 C until an additional 18 ml of water are
removed, resulting in an acrylated polyetherester.
To 100 parts of the product are added 3 parts by weight benzophenone
a~d 1 part benzoin butyl ether. When cast on alurninum panels at 1. 5 ml thick-
ness and cured in air using one 200 W/linear inch medium pressure mercury
vapor lamp at a transport speed of 100 ft. /in., a tack-free, mar-resistant
surface is obtained in two passes.
EXA~PLE XIII
Following the procedure OI Example I, 200 g of a hydroxyl polyester
having an equivalent weight of 200 and functionality of 2. 3, prepared from
1, 3-butylene glycol, glycerine, and a 9/10 mole ratio of adipic acid a~d
isophthalic acid, 292 g adipic acid, and 106 g diethylene glycol were reacted
over a 7-hour period during which time 54 ml of water are removed to afford
~:~L3~
- 31 -
a carboxy functional polyetherester.
To the thus prepared carbo~y functional polyetherester are added 116 g
of 2-hydroxyethylacrylate, 100 ppm methoxy hydroquinone, 100 ppm
phenthiazine and enough hexane to rnaintain a pot temperature of 100 C. The
reaction is conducted over a 5-hour period during ~hich time 18 ml of water
are removed. A clear, viscous acrylated polyetherester oligomer is obtained.
To 100 parts of the resultant polyetherester oligomer are added 3 parts
benzophenone and 1 part benzoin butyl ether. When cast on aluminuYn panels
at 1. 5 ml thickness and cured using one 200 W/linear inch medium pressure
mercury vapor lamp only two passes are required to obtain a tack-free, mar-
st t s f
resl an ur ace.
EXA~PLE XIV
Acrylated urethane resins are prepared employing as precursor com-
pounds 4, 4'-methylene-bis(cyclohexyl isocyanate), 2-hydroxyethyl acrylate
and (a) poly(l, 3-butylene glycol adipate) non-poly(alkylene oxide) polyester
polyol, (b) poly(diethylene glycol adipate) polyetherester polyol, and (c) poly-(dipropylene glycol adipate) polyetherester polyol. Each polyol has an approximate
equivalent weight of 200 and a 2. 3 hydroxyl functionality. In each instance, there
is added to a reaction vessel equipped with stirrer, condensor, thermometer
and gas inlet one equivalent of polyol, 3 equivalents of polyisocyanate and 15
parts by weight of 2-ethylhexyl acrylate. The contents of the reaction vessel are
heated to 70 C under dry air and 0.1 wt. % dibutyl tin dilaurate are added. Thereaction is continued until substantially all of the hydroxyl groups are consumed.
Two equivalents of 2-hydroxyethyl acrylate are added to the reaction vessel and
the reaction is continued until all of the isocyanate groups are consumed. The
reaction vessel is cooled to room temperature. In each instance there is ob-
tained a viscous syrup of acrylated urethane oligomer in 2 ethylhexyl acrylate
reactive monomer diluent at a resin solids concentration of 85 percent by
weight.
Each oligomer is then reduced to 70% total resin solids in 2-ethyl-
hexyl acrylate. To 100 parts of each unsaturated uretha~e oligomer composition
are added four parts of a 1/3 mixture o-f benzoin butyl ether and benzophenone.
.,
- ~3~6
- 32 -
The formulations are cast on aluminum panels at 1. 5 mil thickness and cured
in air using one focused 200 W/linear inch medium pressure mercury vapor
Lamp at a transport speed of 100 ft. /min. The poly(l, 3-butylene glycol adipate)
polyester polyol-based unsaturated urethane compositi~ requires 8 passes to
5 obtain a tack-free, mar-resistant finish; whereas the poly(diethylene glycol
adipate) polyetherester polyol-based and poly(dipropylene glycol adipate) poly-
etherester polyol-based unsaturated urethane compositions require 4 passes
and 5 passes, respectively, to obtain the same level of cure.
EXAMPLE XV
The poly(l, 3-butylene glycol adipate) polyester polyol-based and poly-
(dipropylene glycol adipate) polyetherester polyol-based unsaturated urethane
compositions OI Example I are reduced to 70% total resin solids in 2~ethylhexyl
acrglate. To 100 parts of each composition there is added 7 parts by weight of
a 1/3/3 rnixture of benzoin butyl ether/benzophenone/pentaerythritol tetrakis-
tp-mercaptopropionate). The formulations are cast on aluminum panels at 1. 5
mil thickness and cured in air followins the procedure of Example I. The poly-
ester polyol-based compositions require 8 passes to obtain a tack-free, mar-
resista~t finish; whereas the polyetherester polyol-based compositions require
but 3 passes.
EXAMPLE XVI
To a reaction vessel similar to that employed in Example 1 is added
47.16 g glycerine, 411. 06 g poly(tetraethylene oxide) polyol, 106. 35 g adipic
acid and 21. 02 g isophthalic acid. The reaction mixture is heated to 234 C
and the reaction continued to an acid number of 0. 36. There is obtained a viscous
polyetherester polyol having a hydroxy number of 278 and an acid number of 0. 3 6.
To one equivalent of the thus prepared polyetherester polyol is added
3 equivalents of 4, 4'-methylene-bis(cyclohexyl isocyanate) and 15 parts by
weight 2-ethylhexyl acrylate. The reaction mixture is heated at 70 C until sub-stantially all of the hydroxyl groups are consurned, at which time 2 equivalents
.. .
1~3~
- 33 -
of hydroxyethyl acrylate are added. The reaction is continued until all of the
isocyanate groups are consl~med. There is obtained a viscous syrup of poly-
(tetraethylene oxide) polyetherester-based unsaturated uretha~e oligomer at a
resin solids content of 85 percent by weight.
EXAMPLE XVII
The poly(l, 3-butylene glycol adipate) polyester polyol-based unsaturated
urethane composition (85% resin solids) of Example I and the poly(tetraethylene
oxide adipate) polyetherester polyol-based unsaturated urethane composition
(85 resin solids) of Example III are diluted to 70% resin solids in 2-ethylhexylacrylate. To 100 parts of each diluted composition is added 4 parts by weight ofa 3/1 mixture of benzophenone/benzoin butyl ether. Each of the Iormulations is
coated onto vinyl asbestos lloor tiles and vinyl sheet goods at 1. 5 mil thickness
and cured following the procedure of Example II. The polyester polyol-based
compositions require at least 8 passes to obtain a tack-free, mar-resistant
surface, whereas the polyetherester polyol-based compositions require only 3
passes to obtain a tack-free, mar-resistant surface.
EXAMPLE XVIII
:
A reaction vessel similar to that employed in Example I is charged with
322 g polycaprolactone diol, 319 g 4, 4'-methylene-bis(cyclohexyl isocyanate)
and 200 g 2-ethylhexyl acrylate. The reaction mixture is heated at 70 C until
substantially all of the hydroxyl groups are consumed. 176 g 2-hydroxyethyl
acrylate are added and the reaction continued at 70 C until substantially all
isocyanage functionality is consumed. There is obtained a viscous syrup of
polycaprolactone-based unsaturated urethane oligomer in 2-ethylhexyl acrylate
at a resin solids content of 85 percent by weight.
The thus-prepared unsaturated urethane composition is diluted to 70%
resin solids in 2-ethylhexyl acrylate. To 100 parts of the diluted composition
are 2dded 3 parts by weight benzophenone and 1 part by weight benzoin butyl
ether. The formulation is cast onto aluminum panels at 1. 5 mil wet film thickness
and curing is effected following the procedure of Example I. The polycaprolactone
, . .... . .. . . . ..
~3~46
- 34 -
polyol-based unsaturated urethane compositions require 16 passes to obtain
a tack-free, mar-resistant surface.
E~ PLE XIX
Following the procedure of Example III~ 13. 88 g glycerine, 418. 59 g
~oly(tetraethylene oxide) polyether polyol, 185. 95 g adipic acid and 34. 7 g
isophthalic acid are reacted to form a polyetherester polyol having a hydroxyl
number of 129 and an acid number of 0. 77. One equivalent OI the thus-prepared
polyetherester polyol, three equivalents of 4, 4'-methylene-bis~cyclohexyl
isocyanate) and two e~uivalents of 2-hydroxyethyl acrylate are reacted in 2-
10 ethylhexyl acrylate following the procedure of Example I to obtain a poly-
etherester polyol-based unsaturated urethane oligomer composition at a resin
solids content OI 85 percent by weight.
The thus-prepar~d polyetherester polyol-based unsaturated urethane
oligomer composition ~85~o RSC) and the poly(1, 3-butylene glycol adipate)
polyester polyol-based unsaturated urethane oligomer composition of Example
I (85% RSC) are diluted with N-vinyl pyrrolidone to a solution viscosity of 4000cps at 25 C. Then to 100 parts of each composition are added 4 parts by weight
of a 1/3 mixture of benzoin butyl ether and benzophenone. The resulting
formulations are cast onto aluminum panels at 1. 5 mil wet ~ilm thickness and
20 cured in air by exposure to actinic radiation according to the procedure of
Example II. The polyester polyol-based compositions require 8 passes to
obtain a tack-free, mar~resistant surface. The polyetherester polyol-based
compositions require three passes to obtain the same level of cure.
EXAl~PLE XX
The poly(1, 3-butylene glycol adipate) polyester polyol-based unsaturated
urethane composition (85% RSC) of Example I and the poly(tetraethylene oxide)
polyol polyetherester-~ased unsaturated urethane composition ~85% RSC) of
Example VI are diluted with N-vinyl pyrrolidone to a solution viscosity of
4000 cps at 25 C. Coating compositions containing benzophenone, benzoin
- 35 -
butyl ether and benzophenone/benzoin butyl ether photocatalyst systems are
coated onto aluminum panels at 1. 5 mil wet film thickness and cured in air
by exposure to actinic radiation following the procedure of E2ample I. The
results are reported in the following Table (Table XX-I).
TABLE XX-I
Unsaturated Urethane Type Photocatalyst System
Butyl
Benzoin Passes
Sample Polyester Polyetherester Benzophenone Ether to Cure
1 100 - 1 _ 15
' 2 - 100 1 - 5
3 100 - 2 - 9
4 - 100 2 - 4
100 - 3 8
6 _ 100 3 _ 3
7 100 - 2 1 9
8 - 100 2 1 4
9 - 100 - 1 71 10
- 100 1 2 ~ 3
11 100 - 1 1 10
12 - 100 1 1 4
13 100 - 1 3 q
14 - 100 1 3 2
- 100 - 1 12
16 - 100 _ 3 7
The formulations containing the polyetherester polyol-based unsaturated
urethane resins of the invention cure two to four times faster than equivalent
forrnulations using the non-invention compositions containing polyester polyol-
based unsaturated urethane resins. Formulations containing only benzophenone
and -formulations containing benzophenone/benzoin butyl ether mixtures are
.. . . ~ . . .. .. . . .
- 36 -
effective with the polyetherester polyol-based unsaturated urethane resin
compositions for cure in air by exposure to actinic radiation.
EXAMPLE XXI
Compositions a~ and 12 of Example VI are cast onto alurninum panels
at 1. 5 and 8 mil wet film thickness and cured in air using one 200 W/linear
inch medium pressure mercury vapor larnp at a transport speed of 200 ft. /min.
All coatings obtained a tack-free, mar-resistant surface finish in four passes.
The thin film (1. 5 mil) coatings are completely cured. The underlying regions
of the 8 mil film of cornposition 4 which contains only 2 parts benzophenone is
incompletely cured. Complete cure, surface and bulk, of the 8 mil film o~
composition 12, which contains a 1/1 admixture of benzophenone and benzoin
butyl ether, is obtained.
EXAl!~PLE XXII
To 100 parts of each N-vinyl pyrrolidone-diluted (4000 cps at 25 C)
composition of Example VII are added 4 parts by weight of 1:3 mixture of
benzoin butyl ether and benzophenone. Blends of the compositions are prepared,
cast onto aluminum panels at 1. 5 mil wet film thickness and cured by exposure
to actinic radiation in air following the procedure of Example VIII. The
results are reported in Table XXII-I.
TABLE XXII-I
Unsaturated Urethane Passes
Sample PolyesterPolyetherester To Cure
__
0 100 3
2 25 75 3-4
3 50 50 3-4
4 75 25 4-5
lQ0 0 8
, . . , ~ . . ... . .
- 37 ~
The data indicates that unsaturated urethane compositions containLng
at least about 25 weight percent (based on total unsaturated urethane component)of at least one polyetherester polyoL-based unsaturated urethane resin prepared
according to the invention can be effectively cured in air without significant
5 compromising of cure rate.
EXAMPLE XXIII
Following the procedure of Example VI, a polyetherester polyol is
prepared empLoying as precursor materiaLs 244 g adipic acid, 45 g isophthalic
acid, 250 g poLy(tetraethyLene oxide) poLyol, 110 g 1, 3-butylene gLycol and 20 g
10 glycerine. An unsaturated urethane resin composition is prepared according to- the procedure of Exarnple I from 339 g Oe the thus-prepared poLyetherester polyol,
339 g 4, 4'-methylene-bis(cyclohexyl isocyanate) and 232 g 2~-hydroxyethyl
acrylate in 421. 7 g 2-ethylhexyl acrylate. To 100 parts by weight oF the unsaturated
urethane cornposition there is added 4 parts by weight of a 1:3 mixture of benzoin
15 butyl ether and benzophenone. The formulations are cast onto aluminum panels
at 1. 5 mil wet filrn thickness and cure is effected following the procedure of
Example IX. Only 4 passes are required to obtain a tack-free, mar-resistant
surface (cf. the polyester polyol-based compositions of Example IV require at
least 8 passes at a slower transport speed to obtain the same level of cure).
EXAMPLE ~IV
Following the procedure of Example VI, a polyetherester polyol is prepared
employing as precursor mater~als 200. 0 g (1 eq. ) of 1, 3-butylene glycol/glycerine/
adipic acid/isophthalic acid polyester polyol having a hydroxy functionality of 2. 3,
53. 0 g diethylene glycol and 146. 0 g adipic acid. An unsaturated oligomer com-
25 position (70~O RSC in 2-ethylhexyl acrylate) is prepared according to the pro-
cedure of Example I from 273. 0 g of the thus-prepared polyetherester polyol~
269. 0 g 4, 4'- nethylene-bis(cyclohexyl isocyanate3, and 159. 0 g 2-hydroxy
ethyl acrylate in 300. 0 g 2-ethylhexyl acrylate To 100 parts of the resulting
polyetherester polyol-based unsaturated urethane composition is added 4 parts
30 by weight of a 3:1 mixture of benzophenone and benzoin butyl ether. The
. .. . . .
~3
~ 3~ -
for~nulation is coated onto aluminum panels at 1. 5 mil wet film thickness and
cured in air by exposure to actinic radiation in accordance with the procedure.
Three passes are required to obtain a tack-free, mar-resistant surface finishO
The data demonstrate that unsaturated urethane oligomer composi~ions
derived from poly(alkylene oxide) polyols cure ln air at a rate significa~tly
greater than do such oligomer compositions derived from polyester polyols which
do not contain residues of poly(alkylene oxide) polyols in -the main chain. The
data also dernonstrate that acrylated polyether and polyetherester compositions
derived from poly(alkylene oxide) polyols cure in air at a rate significantly greater
than do such oligomer compositions derived from polyester polyols which do
not contain residues of poly(alkylene oxide) polyols in the main chain.
... ..
