Note: Descriptions are shown in the official language in which they were submitted.
13(~)307
Case 3-13925/ARZ 324/+
PHOTOPOLYMERISATION BY MEANS O~ ORGANOMETALLIC SALTS
THIS INVENTION relates to compositions comprising 1,2-epoxides
and certain types of organometallic salts, and optionally certain
types of photoaccelerators. It also relates to the polymerisation
of such compositions by means of actinic radiation, to the further
crosslinking of polymerised products so obtained by means of heat
in the presence of heat-curing agents, and to the use of the
compositions as surface coatings, in printing plates, in printed
circuits, and in reinforced composites, and as adhesives.
For a number of reasons it has become desirable to induce
polymerisation by means of actinic radiation. Employing
photopolymerisation procedures may, for example, avoid the use
of organic solvents with their attendant risks of toxicity,
flammability, and pollution, and the cost of recovering the
solvent. Photopolymerisation enables insolubilisation of a
composition to be restricted to defined areas, i.e., those which
have been irradiated, and so permits the production of printed
circuits and printing plates or allows the bonding of substrates
to be confined to required zones. Further, in production processes,
irradiation procedures are often more rapid than those involving
heating and a consequential cooling step.
In United States Patent Specification No, 3 709 861 there
are described curable compositions comprising (a) an epoxide
.
~ '
'7
130~3Q~
resin, (b) a polycarboxylic acid anhydride or polymercaptan as curing
agent, and (c) a cyclopentadienylmanganese tricarbonyl as a light-
activated accelerator. When curing i9 desired, the compositions
are exposed to actinic radiation for 10 minutes to 8 hours
(irradiation times from 15 minutes to 3 hours are used in the
Examples). Exposure at room temperature produces a cure that is
dry to the touch, but the composition can be heated, simultaneously
with or subsequent to the exposure, at 50 to 250 C for 1 hour to
3 days to accelerate and complete the cure.
We have now found that 1,2-epoxides can be photopolymerised
by means of certain salts of complexes of transition metals with
arenes and cyclic dienes. These salts are in general soluble
in liquid 1,2-epoxides and so are readily incorporated to form a
photopolymerisable composition without the need to use toxic
or inflammable solvents or complex dispersion means.
The salts used in the compositions of this invention
have little or no effect on heating with 1,2-epoxides in the
absence of actinic radiation. Thus, a composition comprising
2 parts by weight of tricarbonyl(cyclohexa-2,4-dienylium)iron
tetrafluoroborate and 100 parts by weight of a commercially-
available epoxide resin, the diglycidyl ether of 2,2-biSC4-
hydroxyphenyl~propane, did not gel on heating at 150C for
40 hours. It follows that, protected from actinic radiation,
compositions of the present invention have desirably long pot-
lives.
.
13V0307
~ 3 ~
Accordmg to the present invention there is providedpolymerisable compositions comprising
(a) a compound, or mixture of compounds, containing at
least one 1,2-epoxide group,
(b) an effective amount of a salt of the formula
r 1+
LY - Q ~ (C)a ~ n
where
Y represents an arene group or a diénylium group,
Q represents an atom of a d-block transition element chosen
from titanium, vanadium, chromium, manganese, iron, cobalt,
nickel, copper; niobium, molybdenum, ruthenium, rhodium,
palladium, silver; tantalum, tungsten, rhenium, osmium,
iridium, platinum, and gold,
a is a positive integer such that the atom Q has a
closed electron shell configuration,
M represents an atom of a metal or metalloid,
E
13~03(~
-- 4 --
n is 4, 5, or 6, and is one more than the valency of M, and
X represents a fluorine or chlorine atom, with the proviso
that if M represents antimony, n is 6, and five of the symbols X
represent fluorine, then one may alternatively represent a hydroxy
group; and
(c) a photoaccelerator, said photoaccelerator ~eing selected
from the group consisting of:
(i) a ketal of an aromatic diketone;
(ii) an aromatic-aliphatic ketone of one of the for~ulae
~ R 1 X
L Rll I
R'13 R13
Arl CO C R12 C CO-A 1 XI
Rll R 11
R R
1 0 C Rlh C CO-Arl XII
R.ll ~1
XlII
E
13~)03~7
- 4~ -
where
Ar represents a phenyl group which is unsubstituted or is substi-
tuted by up to 3 substituents chosen from halogen atoms, alkyl or
allcoxy gro~ll)s of l to /~ c~rbon atollls,a~ >l~cl)yl ~rouls,
R and R each denote a monovalent aliphatic, cycloaliphatic,
or araliphatic group, or together with the attached carbon atom may
denote a cycloalkylene group,
R is a carbon-carbon bond or a divalent organic radical,
R represents a hydroxyl group or an amino group, or a
monovalent etherified or silylated such group,
R represents a divalent amino, ether, or siloxy group,
R represents a direct chemical bond or -CH2-, and
R represents -O-, -S-, -S02-, -CH2-, or -C(CH3)2-; and
(iii) a 2-substituted thioxanthone of formula
~ CO ~ Rl7 XIV
where R 7 denotes either a c~lorine atom or an alkyl group of
1 to 6 carbon atoms.
Another aspect of this invention provides a process for the
transformation into higher-molecular weight material of a compound
containing at least one 1,2-epoxide group, or a mixture of such
compounds, comprising subjecting a said composition of this
invention to actinic radiation.
When Y denotes an arene group i.e., is itself a 6-electron
ligand, this may be a mononuclear or polynuclear group, including
E
13~t~3U7
- 4b -
a condensed ring group. Preferably it is a hydrocarbon group,
optionally substituted by one or more alkoxy groups, and preferably
it contains from 6 to 18 carbon atoms, such as benzene, toluene,
mesitylene, naphthalene, biphenyl, phenanthrene, fluorene, and
anthracene.
When Y denotes a dienylium group it is preferably a cyclic
group of one of the following formulae
Rlb~ Rlb~
II III I~
E
-- 13V03(~7 --
~ 5 _
Rlb~3 Rl~
V VI
where
R denotes an alkyl group of 1 to 4 carbon atoms, an alkoxy
group of 1 to 4 carbon atoms, or an alkyl group interrupted by
one or more oxycarbonyl groups and containing up to 12 carbon
atoms, and
b is æero, 1,2, or 3.
Q preferably represents chromium, cobalt, nickel, and
particularly iron or manganese.
The atom M may represent, for example, iron, tin, bismuth, aluminium,
gallium, indium, titanium, æirconium, scandium, vanadium, chromium, or
manganese, but preferably it represents antimony, arsenic, boron, or
phosphorus. The cation MXn may thus denote tetrachloroaluminate or
hexachloroferrate, for example, but it preferably denotes
tetrafluoroborate, hexafluoroarsenate, hydroxopentafluoroantimonate,
hexafluoroantimonate, or hexafluorophosphate.
Salts of formula r where Y denotes an arene group may be
prepared by heating, for e~ample, pentacarbonylmanganese bromide
with an arene in the presence of alu~inium chloride and
treating the product in aqueous solution with, for example,
potassium hexafluorophosphate, to precipitate the
E
l3ua3~7
arenetricarbonylmanganese hexafluorophosphate (T.H, Coffield,
V. Sandel, and R.D. Closson, J. Amer. Chem. Soc., 1957, 79, 5826).
Individual salts of formula I, where Y denotes an arene
group, which are particularly preferred include the hexafluoro-
phosphates of ~-toluenetricarbonylmanganese, ~-benzenetricarbonyl-
manganese, ~-mesitylenetricarbonylmanganese, ~ methyl-5,6,7,8-
tetrahydronaphthalenetricarbonylmanganese, ~-hexylbenzenetricarbonyl-
manganese, ~-methoxybenzene tricarbonylmanganese, and ~-hexyloxy-
benzenetricarbonylmanganese.
These salts satisfy the requirement that the central atom
(manganese) has a closed electron shell configuration, i.e.,
18 electrons in its valency shell, univalent manganese in the
unipositive cation contributing 6 electrons, the arene group
contributing 6 electrons, and the three carbonyl groups
contributing 2 electrons each.
Salts of formula I where Y denotes a dienylium group are
likewise in general known.
For example, a diene is heated with a metal carbonyl such
as iron pentacarbonyl to form a neutral complex, e.g., tricarbonyl-
(cyclohexa-1,3-diene)iron, and abstraction of a hydride ion from
the complex by means of triphenylmethyl tetrafluoroborate yields
the corresponding tricarbonyl(cyclodienylium)iron tetrafluoro-
borate (EØ Fischer and R.D. Fischer, Angew. Chem., 1960, 72,
919; A.J. Birch, K.B. Chamberlain, M.A, Haas, and D.J. Thompson,
J. Chem. Soc., Perkin 1, 1973, 18822. The hexafluorophosphate
or other desired salt of formula I may be made similarly, using
13~t~;!3~
triphenylmethyl hexafluorophosphate and sinilar salts.
Reaction of cyclopentadienyliron dicarbonyl bromide with
carbon monoxide in an inert solvent in the presence of
aluminium tribromide as catalyst followed by hydrolysis and
then treatment with ammonium hexafluorophosphate affords
tricarbonyl(cyclopentadienyl)iron hexafluorophosphate
(E.O. Fischer and K. Fichtel, Chem. Ber., 1961, 94, 1200).
Reaction of a cyclopentadienyliron dicarbonyl halide with
carbon monoxide in acetone solution with sodium tetraphenylborate
yields tricarbonyl(cyclopentadienyl~iron tetraphenylborate
(A. Davison, M.L.H. Green, and G. Wilkinson, J. Chem. Soc,,
1961, 3172), from which salts such as the tetrafluoroborate
may be prepared.
Or such a cyclodienyliron dicarbonyl halide may be carbonylated
in the presence of a mixture of hexafluorophosphoric acid and propionic
anhydride to afford tricarbonyl(cyclopentadienyl)iron,
tricarbonyl(cycloheptatrienyl~iron, and tricarbonyl(cyclo-octa-
tetraenyl)iron hexafluorophosphates (R.B. King, Inorg. Chem.,
1962, 1, 964).
Tetracarbonyl(cyclopentadienylium)molybdenum hexafluoro-
phosphate and tetracarbonyl(cyclopentadienylium)tungsten hexa-
fluorophosphates can be made by reaction of cyclopentadienyl-
molybdenumtricarbonyl chloride and the corresponding tungsten
compound with carbon monoxide in the presence of aluminium chloride
followed by treatment of the tetracarbonyl(cyclopentadienylium~
tetrachloroaluminate with ammonium hexafluorophosphate (E.O. Fischer,
13U~307
- 8 -
K. Fichtel, and K. Ofele, Chem. Ber., 1962, 95, 249~252~.
Tetracarbonyl(cyclopentadienyl)chromium tetrafluoroborate
can be obtained by reaction of hydridotricarbonyl(cyclopentadienyl~-
chromium with boron trifluoride dimethyl etherate in benzene under
an atmosphere of carbon monoxide (EØ Fischer and K. Ulm, Z.
Naturforsch., 1961, 16 B, 757).
Individual salts of formula I, where Y denotes a cyclic
dienylium group, which are particularly preferred include
tricarbonyl(cyclohexa-1,3-dienylium)iron tetrafluoroborate,
tricarbonyl(l-methylcyclohexa-2,4-dienylium)iron hexafluorophosphate,
tricarbonyl(l-methyl-4-methoxycyclohexa-2,4~dienylium)iron
hexafluorophosphate, tricarbonylC2-methoxybicyclo L4.4.~ deca-
2,4-dienylium)iron hexafluorophosphate, tricarbonyl(l-(acetoxy-
methyl)-2-(methoxycarbonylacetoxy~ethylcyclohexa-2,4-dienylium)-
iron hexafluorophosphate, tricarbonyl(l-ethyl-4-isopropoxycyclohexa-
2,4-dienylium)iron hexafluorophosphate, and tricarbonyl(l-(methoxy-
carbonyl)-4-methoxycyclohexa-2,4-dienylium)iron tetrafluoroborate.
These salts likewise satisfy the requirement that the central
atom tiron ) has a closed electron shell configuration, the iron
contributing 7 electrons, the dienylium group contributing 5,
and the carbonyl groups also contributing 2 each ~i.e., 18 in all~.
~3003~7
g
The compositions of this inyention preferably contain 0.5 to
7.5, and particularly 1 to 5.0, parts by weight of (b? per 100
parts by weight of (a).
Suitable mono-1,2-epoxides include epichlorohydrin, propylene
oxide, glycidyl ethers of monohydric alcohols or phenols, such as
n-butyl glycidyl ether or phenyl glycidyl ether, and glycidyl
esters of monocarboxylic acids, such as glycidyl acrylate or
glycidyl methacrylate. Preferably ~a~ is an epoxide resin,-i.e.,
a compound containing on average more than one 1,2-epoxide group
per molecule, such as a resin containing more than one terminal
group of formala
~0~
- CH - C - CH VII
12 R3 R4
directly attached to an atom of oxygen, where either R and R4
each represent a hydrogen atom, in which case R3 denotes a hydrogen
atom or a methyl group, or R2 and R4 together represent -CH2CH2-,
in which case R denotes a hydrogen atom.
As examples of such resins may be mentioned polyglycidyl
and poly(~-methylglycidyl) esters obtainable by reaction of a
compound containing two or more carboxylic acid groups per molecule
with epichlorohydrin, glycerol dichlorohydrin, or ~-methyl-
epichlorohydrin in the presence of an alkali. Such polyglycidyl
esters may be derived from aliphatic polycarboxylic acids, e.g.,
succinic acid, glutaric acid, adipic acid, pimelic acid, suberic
~3()V3~
-` 10 ~
acid, azelaic acid, sebacic acid, or dimerised or trimerised
linoleic acid; from cycloaliphatic polycarboxylic acids such as
tetrahydrophthalic acid, 4-methyltetrahydrophthalic acid,
hexahydrophthalic acid, and 4-methylhexahydrophthalic acid; and
from aromatic polycarboxylic acids such as phthalic acid, iso-
phthalic acid, and terephthalic acid. Other suitable polyglycidyl
esters are obtainable by polymerisation of glycidyl esters of
vinylic acids, especially glycidyl acrylate and glycidyl methacrylate.
Further examples are polyglycidyl and poly(~-methylglycidyl)
ethers obtainable by reaction of a compound containing at least two
free alcoholic hydroxyl and/or phenolic hydroxyl groups per molecule
with the appropriate epichlorohydrin under alkaline conditions or,
alternatively, in the presence of an acidic catalyst and subsequent
treatment with alkali. These ethers may be made from acyclic
alcohols such as ethylene glycol, diethylene glycol, and higher
poly(oxyethylene) glycols, propane-1,2-diol and poly(oxypropylene)
glycols, propane-1,3-diol, poly(oxytetramethylene) glycols, pentane-
1,5-diol, hexane-2,4,6-triol, glycerol, l,l,l-trimethylolpropane,
pentaerythritol, sorbitol, and poly(epichlorohydrin), from
cycloaliphatic alcohols such as resorcitol, quinitol, bis(4-hydroxy-
cyclohexyl)methane, 2,2-bis(4-hydroxycyclohexyl)propane, and
1,1-bis(hydroxymethyl)cyclohex-3-ene; and from alcohols having
aromatic nuclei, such as N,N-bis(2-hydroxyethyl)aniline and
p,p'-bis(2-hydroxyethylamino)diphenylmethane. Or they may be made
from mononuclear phenols, such as resorcinol and hydroquinone, and
from polynuclear phenols, such as bis(4-hydroxyphenyl)methane
i300;~7
(otherwise known as bisphenol F), 4,4'-dihydroxydiphenyl, bis(4-
hydroxyphenyl) sulphone, 1,1,2,2-tetrakis(4-hydroxyphenyl)ethane,
2,2-bis(4-hydroxyphenyl)propane (otherwise known as bisphenol A),
2,2-bis(3,5-dibromo-4-hydroxyphenyl)propane, and novolaks formed
from aldehydes such as formaldehyde, acetaldehyde, chloral, and
furfuraldehyde, with phenol itself, and phenol substituted in the
ring by chlorine atoms or by alkyl groups each containing up to
nine carbon atoms, such as 4-chlorophenol, 2-methylphenol, and
4-tert.butylphenol.
Poly(N-glycidylj compounds may also be used, e.g., N-glycidyl
derivatives of amines such as aniline, n-butylamine, bis(4-amino-
phenyl)methane, and bis(4-methylaminophenyl)methane; triglycidyl
isocyanurate; and N,N'-diglycidyl derivatives of cyclic alkylene
ureas, such as ethyleneurea and 1,3-propyleneurea, and of hydantoins
such as 5,5'-dimethylhydantoin. In general, however, they are not
preferred.
Poly(S-glycidyl) compounds may also be used, e.g., di(S-
glycidyl) derivatives of dithiols such as ethane-1,2-dithiol and
bis(4~mercaptomethylphenyl) ether, but they also are not preferred.
Examples of epoxide resins having groups of formula Y where
R 2 and R 4 conjointly denote a -C~2CH2- group are bis(2,3-epoxy-
cyclopentyl) ether, 2,3-epoxycyclopentyl glycidyl ether, and
1,2-bis(2,3-epoxycyclopentyloxy)ethane.
Epoxide resins having the 1,2-epoxide groups attached to
different kinds of hetero atoms may be employed, e.g., the glycidyl
ether-glycidyl ester of salicylic acid.
~3(J0307
- 12 ~
Epoxide resins in which some or all of the epoxide groups are
not terminal may also be employed, such as vinylcyclohexene dioxide,
limonene dioxide, dicyclopentadiene dioxide, 4-oxatetracyclo-
r 6.2.1.02'7Ø3'5] undec-9-yl glycidyl ether, 1,2-bis(4-
oxatetracyclo r6.2.1.0 '7Ø ' ~undec-9-yloxy)ethane, 3,4-
epoxycyclohexylmethyl 3',4'-epoxycyclohexanecarboxylate and its
6,6'-di~ethyl derivative, ethylene glycol bis(3,4-epoxycyclohexane-
carboxylate), 3-(3,4-epoxycyclohexyl)-8,9-epogy-2,4-dioxaspiro-
[5,5] undecane, and epoxidised butadienes or copolymers of
butadiene with ethylenic compounds such as styrene and vinyl acetate.
If desired, a mixture of epoxide resins may be used.
Especially preferred epoxide resins used in this invention are
diglycityl ethers, which may have been advanced, of dihydric phenols
such as 2,2-bis(4-hydroxyphenyl)propane and bis(4-hydroxyphenyl)-
methane and of dihydric aliphatic alcohols such as butane-1,4-diol.
Nhen Y denotes an arene group it will normally be necessary
to apply heat as well as actinic radiation to bring about curing
if the epoxide groups in (a) are of formula VII: with such salts
the use of epoxide resins where the 1,2-epoxide groups are directly
linked to cycloaliphatic carbon atoms is preferred,
Preferably the compositions of this invention also contain a
photoaccelerator. We have found that, by incorporation of suitable
photoaccelerators, the speed of curing is further increased, thereby
permitting the use of shorter exposure times and/or of less powerful
sources of irradiation.
~300307
- 13 -
Substances suitable for use as the photoaccelerator include
ketals of aromatic diketones, particularly compounds of
formula
Arl -- C=O Arl--C=O
Ar C(OCH2R ~2 or Ar - C \ R6
VIII IX
where
R5 represents a hydrogen atom, an alkyl group of 1 to 5
carbon atoms, an alkenyl group of 2 or 3 carbon atoms, an
aralkyl group of 7 to 9 carbon atoms, an aralkenyl group of
8 or 9 carbon atoms, or a group of formula -(CH2~mR
wherein
R denotes a halogen atom or a group of formula _oR8 ,
-SR8 -OAr3, -SAr3, -OCOR8 , or -COOR
m is 1, 2, or 3,
R6 represents a group of formula -CH2CH(R9 )- or
-CH2CH(R )CH2 ,
R denotes an alkyl group of 1 to 4 carbon atoms,
R 9 denotes a hydrogen atom or an alkyl group of 1 to
18 carbon atoms, and
Arl, Ar2, and Ar3 each independently represent a phenyl
group which is unsubstituted or is substituted by up to 3
substituents chosen from halogen atoms, alkyl or alkoxy groups
~of 1 to 4 carbon atoms, and phenyl groups.
13V0307
Examples of compounds of formula VIII are benzil dimethyl ketal,
benzil diethyl acetal, benzil di(2-methoxyethyl) ketal, and benzil
di(2-chloroethyl) ketal. Examples of compounds of formula IX are
2-phenyl-2-benzoyl-4-methyl-1,3-dioxolane and 2-phenyl-2-benzoyl-
1,3-dioxane. The particularly preferred photosensitiser is benzil
dimethyl ketal.
Compounds of formula VIII or of formula IX are described in
British Patent Specification ~o. 1 390 006, where they are
employed for the photopolymerisation and photocrosslinking of
ethylenically-unsaturated compounds such as methyl acrylate,
styrene-containing polyesters based on maleic acid, and diallyl
phthalate prepolymers.
Other substances suitable for use as the photoaccelerator
include aromatic-aliphatic ketones of one of the formulae
Arl ~ CO - C - R ~ X
R
R13 R13
A 1 CO C R12 C CO Arl XI
Rll R 11
R10 10
A 1 CO C R14 C CO Arl XII
R 11 ~.1.
13~037
R
~ 16 ~ XIII
where
Ar has the meaning assigned above,
R10 and Rll each denote a monovalent aliphatic, cyclo-
aliphatic, or araliphatic group, or together with the attached
carbon atom may denote a cycloalkylene group,
R is a carbon-carbon bond or a divalent organic radical,
Rl3 represents a hydroxyl group or an amino group, or
a monovalent etherified or silylated such group,
R represents a divalent amino, ether, or siloxy group,
Rl5 represents a direct chemical bond or -CH2-, and
R represents -O-, -S-, -S02-, -C~2-, or -C(CH3)2-.
These compounds, preferred members of which include
2-allyloxy-2-methylpropiophenone, 2-benzyloxy-2-methyl-
propiophenone, 2-hydroxy-2-methyl-p-phenoxypropiophenone,
l-benzoylcyclohexanl. l-benzoylcyclopentanol, and bis(4-(~-
hydroxyisobutyryl2phenyl2 ether, are likewise described as
photopolymerisation catalysts for ethylenically-unsaturated
compounds and as photocrosslinkers for polyolefins in European
Patent Application ~o. 0 003 002 (published July ll, 1979).
Other compounds which may be used to enhance the
photopolymerising rate of 1,2-epoxides by the salts of formula I
~3(~J3C~7
- 16 -
are 2-substituted thioxanthones of formula
~ 5 ~ R17 XIV
where R17 denotes either a chlorine atom or an alkyl group of
1 to 6 carbon atoms such as an isopropyl or tert.butyl group.
Compounds of formula XIV, especially the 2-chloro compound, are
used commercially as photopolymerisation catalysts for
ethylenically-unsaturated compounds and as photocrosslinkers
for polyolefins.
That compounds of formula VIII to XIV accelerate the
photoinduced polymerisation of 1,2-epoxides by means of
organometallic salts is therefore unexpected.
We prefer to include from 0.5% to 7.5%, and especially from
1% to 5%, by weight of the photoaccelerator, calculated on the
weight of (a).
In the photopolymerising step actinic radiation of
wavelength from 200 to 600 nm is preferably used. Suitable
sources of actinic radiation include carbon arcs, mercury vapour
arcs, fluorescent lamps with phosphors emitting ultraviolet
light, argon and xenon glow lamps, tungsten lamps, and photo-
graphic flood lamps. Of these, mercury vapour a.cs, particularly
sun lamps, fluorescent sun lamps, and metal halide lamps are
most suita~le. The time required for the exposure will depend
~3(~0307
~ 17 ~
upon a variety of factors which include, for example, the
individual polymerisable s~bstance used, the type of light
source, and its distance from the irradiated material.
Suitable times may be readily determined by those familiar with
photopolymerisation techniques. If, as in a process described
below, it is necessary that the product so photcpolymerised
must still be curable on heating with a heat-curing agent
admixed therewith, then, of course, irradiation is carried
out at a temperature below that at which substantial heat-
curing of the photopolymerised product by means of the heat-
curing agent would occur.
The compositions of this invention may be used as surface
coatings. They may be applied to a substrate such as steel,
aluminium, copper, ca*m;um, zinc, paper, or wood, preferably as
a li~uit, and irradiated. By polymerising part of the coating,
as by irradiation through a mask, those sections which have not
been exposed may be washed with a solvent to remove the unpolymerised
portions while leaving the photopolymerised, insoluble portions
in place. Thus the compositions of this invention may be used
in the production of printing plates and printed circuits.
Methods of producing printing plates and printed circuits from
photopolymerisable compositions are well known (see, e.g.,
British Patent Specification No. 1 495 746).
The compositions may also be used as adhesives. A layer of the
composition may be sandwiched between two surfaces of objects, at
least one of which is transparent to the actinic radiation, e.g.S
~3()03(~7
- 18 -
of glass, then the assembly is irradiated and, if desired. heated
~ to complete the polymerisation.
The compositions are also useful in the production of fibre-
reinforced composites, including sheet moulding compounds.
They may be applied directly, in liquid form, to reinforcing
fibres ~including strands, filaments, and whiskers), which may be
in the form of woven or nonwoven cloth, unidirectional lengths, or
chopped strands,
The fibre-reinforced composite may be made by a batch process,
the fibrous reinforcing material being laid on a film of the
photopolymerised composition, which is advantageously under slight
tension, when a second such film may, if desired, be laid on top,
and the assembly is pressed while being heated. It may also be
made continuously, such as by contacting the fibrous reinforcing
material with a film of the photopolymerised composition, then, if
desired, placing a second such film on the reverse face of the
fibrous reinforcing material and applying heat and pressure. More
conveniently, two such films, preferably supported on the reverse
side by belts or strippable sheets, are applied simultaneously to the
fibrous reinforcing material so as to contact each exposed face.
When two such films are applied, they may be the same or different.
Multilayer composites may be made by heating under pressure
interleaved films and layers of one or more fibrous reinforcing
materials. ~hen unidirectional fibres are used as the reinforcement
material, successive layers of them may be oriented to form cross-
13VC~30'7
-- 19 --
ply structures.
With the fibrous reinforcing material there may be used
additional types of reinforcement such as a foil of metal or a
sheet of a plastics material or of a rubber.
In the production of sheet moulding compounds, a composition
of this invention, together with the chopped strand reinforcing
material and any other components, are exposed to irradiation
in layers through supporting sheets.
The polgmerisable composition is preferably applied so that
the composite contains a total of from 20 to 80% by weight of
the said composition and, correspondingly, 80 to 20~ by weight
of the reinforcement. More preferably, a total of 30 to 50
by weight of the composition is employed.
The compositions of this invention are useful in the
production of putties and fillers. They may be used as dip-coatings,
an article to be coated being dipped in the liquid composition,
withdrawn, and the adhering coating being irradiated to photo-
polymerise, and hence solidify it, and subsequently, if desired,
being heated.
We have found that it is possible, using the compositions
of this invention, to cure epo~ide resins in two stages; the
resin is first converted into the partially cured B-stage by
exposing it to actinic radiation in the presence of a said
organometallic salt and a latent, heat-activated crosslinking
agent for the epoxide resin and, in a second stage, the partially
13UC~3(.~7
- 20 -
cured composition is heated so that curing is completed by means
of the heat-activated crosslinking agent. Thus, a liquid or
semiliquid composition may be prepared, which may then be shaped
or used to impregnate a substrate while being irradiated to
solidify it; then the solidified body is heated when desired,
to complete the cure of the resin.
According, therefore, to another embodiment of this invention,
an epoxide resin is.irradiated, in the presence of an amount of
an organometallic salt of formula I effective for the polymerisation
of the epoxide resin and of a curing amount of a latent heat-curing
agent for the epoxide resin, to form a B-stage product and, when
desired, curing of the composition is completed by heating it.
A further embodiment comprises a composition containing an
epoxide resin, an amount of an organometallic salt of formula I
effective for polymerisation of the said epoxide resin on exposure
of the composition to actinic radiation, and a curing amount of
a latent heat-curing agent for the epoxide resin.
Suitable heat-activated crosslinking agents for the epoxide
resin compositions include polycarboxylic acid anhydrides, complexes
of amines, especially primary or tertiary aliphatic amines such as
ethylamine, trimethylamine, and n-octyldimethylamine, with boron
trifluoride or boron trichloride, and latent boron difluoride
chelates. Aromatic polyamines and imidazoles are usually not
preferred, because indifferent results are obtained, possibly due to
reaction between the acid catalyst ~iberated and the amine.
Dicyandiamide can be used successfully, providing it is in relatively
coarse particles.
13()~3~7
The temperature and duration of heating required for the thermal
curing and the proportions of heat-activated curing agent are readily
found by routine experimentation and easily derivable from what is
already well known concerning the heat-curing of epoxide resins.
By virtue of the compositions having groups through which
they can be heat-cured after photopolymerisation, they are
particularly useful in the production of multilayer printed circuits,
Conventionally, a multilayer printed circuit is prepared from
several double~sided printed circuit boards of copper, stacked one
on top of another and separated from each other by insulating sheets,
usually of glass fibre impregnated with an epoxide resin in the
B-stage. If a heat-curing agent is not admixed with the layer of
pho~opolymerisable epoxide resin in the circuit board, it can be
incorporated in the insulating layers which alternate with the
plates, these layers conveniently being of an epoxide resin
prepreg; sufficient of the heat~curing agent contained in the
prepreg, providing the latter is not too thick, migrates to induce
crosslinking of the photopolymerised epoxide resin. The stack
is heated and compressed to bond the layers together. Conventional
photopolymerisable materials, however, do not form strong bonds
either with copper or with resin-impregnated glass fibre sheets.
A stack which is bonded with the photopolymer still covering the
copper is therefore inherently weak and in use can become delaminated.
It is therefore normal practice to remove the residual photopolymer
after the etching stage, either by means of powerful solvents or by
a mechanical method, e.g., by means of brushes. Such a stripping
process can damage the copper of the printed circuit or the surface
130~;~0~
- 22 -
of the laminate on which the circuit rests, and so there is a need
for a method which would avoid the necessity of removing the
photopolymerised material prior to bonding the boards together.
The presence of residual 1,2-epoxide groups means that cross-
linking can occur when the hoards axe bonded, resulting in goodadhesion to the copper and to the resin~impregnated glass fibre
substrate, so avoiding the necessity just referred to.
Another application involving heat-curing after photopolymerisation
of the compositions of this invention is in filament winding. Thus,
a continuous tow of fibrous reinforcement is impregnated with a
composition containing a latent heat-curing agent for epoxide resins
and then wound around a mandrel while exposing the winding the
actinic radiation. Such filament windings still have a degree of
flexibility, permitting the mandrel to be removed more readily
than when a rigid winding is formed in one step. When required,
the winding is heated to crosslink the composition.
In a further such application, a layer of the composition
in liquid form is irradiated until it solidifies, producing a
film adhesive which is then placed between, and in contact with,
two surfaces which are to be bonded together, and the assembly is
hea~ed to complete crosslinking of the composition. The film may
be provided on one face with a strippable backing sheet.
Manipulation of the assembly is often easier if the film has a
tacky surface. This may be produced by coating the film with a
substance which is tacky at room temperature but which crosslinks
1300~07
- 23 -
to a hard, insoluble, infusible, resin under the conditions of heat
employed to complete crosslinking of the composition. However, an
adequate degree of tackiness often exists without additional
treatment, especially if polymerisation of the composition has
not proceeded too far. Suitable adherends include metals such as
iron, zinc, cadmium, copper, nickei, and aluminium, ceramics, glass,
and rubbers.
The following Examples illustrate the invention. Unless
otherwise indicated, parts are by weight.
Epoxide Resin I denotes a diglycidyl ether of 2,2-bis(4-
hydroxyphenyl)propane, of epoxide content 5.2 equiv./kg.
Epoxide Resin II denotes 3,4-epoxycyclohexylmethyl
3,4-epoxycyclohexanecarboxylate.
Epoxide Resin III denotes an advanced epoxide resin of epoxide
content 2.30 equiv./kg, made by reaction in a conventional manner
of bisphenol A diglycidyl ether (38.56 parts) and bisphenol A
(10.82 parts).
Epox~de Resin rv denotes a diglycidyl ether of 1,4
butanediol, of epoxide content 9.35 equiv./kg.
Epoxide Resin V denotes an epoxidised bisphenol A novolak
having a softening point of 72 C and an epoxide content of
4.9 equiv./kg.
Organoiron salts employed in these Examples are prepared
as described by A.J. Birch et al., loc. cit.
~ Methyl-5,6,7,8-tetrahydronaphthalene-tricarbonylmanganese
hexafluorophosphate
This is made following the method of T,H, Coffield,
V. Sandel, and R.D. Closson, loc. cit.
~3(~0307
- 24 ~
A mixture of pentacarbonylmanganese bromide (2,5 g),
aluminium chloride (2 g), and l-methylnaphthalene is stirred for
6 hours under nitrogen at 100 C, The mixture is cooled and
hydrolysed with 100 g of ice water, and to the separated aqueous
S solution is added potassium hexafluorophosphate (1.7 g? dissolved
in 30 ml of water. The yellow precipitate is filtered off, washed
with ice water~and dried for 16 hours at 40C/13000 N/m . The
product has a m.pt. 175 C (decomp.~
OEound: C, 39.55; H, 3.25; F, 26.6; Mn, 12.6; P, 7.2;
C14H14F6MnO3P requires C, 39.09; H, 3.28; F, 26.50; Mn, 12.77;
P, 7.20%).
-Toluene-tricarbonylmanganese hexafluorophosphate
This is made similarly, by the method of T.H. Coffield et al.
(loc. cit.). The product melts at above 250C.
(Found: C, 31.9; H, 2.2; F, 31.7; Mn, 14.8. Calc, for
ClOH8F6MnO3P;C, 31.94; H, 2.14; F, 30.31; Mn, 14.61; 0, 12.76;
P, 8.24Z).
~-Methoxybenzene-tricarbonylmanganese hexafluorophosphate
A mixture of pentacarbonylmanganese bromide (2.5 g~,
aluminium chloride (2 g) and methoxybenzene (30 ml) is heated
to 110C for 3.5 hours with stirring under nitrogen. The mixture
is cooled and hydrolysed with 100 g ice-water and to the
separated aqueous solution is added potassium hexafluorophosphate
(1.7 g) dissolved in 30 ml of water. The yellow precipitate
is filtered off, washed with ice-water and dried for 16 hours
at 40C/13000 N/m2. The product melts at above 290C.
130030~
- 25 -
(Found: C, 30.5; H, 2.2; F, 29.6; Mn, 13.4.
ClOH8F6MnO4P requires C, 30.64; H, 2.06; F, 29.07; Mn, 14.01. )
~-Hexyloxybenzene-tricarbonylmanganese hexafluorophosphate
This is made similarly to the corresponding methoxybenzene
compound, hexyloxybenzene ~30 ml) being used in place of the
methoxybenzene. The product melts at 146-151 C.
~-Hexylbenzene-tricarbonylmanganese hexafluorophosphate
This is made similarly to the corresponding methoxybenzene
compound, hexylbenzene (10 ml.2 being used together with
octane t20 ml2in place of the methoxybenzene. The product
melts at 148-151C.
(Fount: C, 39.9; H, 4.1; F, 25.8; Mn, 12Ø
C15H18F6MnO3P requires C, 40.38; H, 4.07; F, 25.55; Mn, 12.31.
EXAMPLES 1-6
Epoxide Resin I and tricarbonyl(cyclohexadienylium)iron salts
are mixed as listed in the following Table, the compositions
are drawn as films ~m thick on tinplate and then subjected
at a distance of 20 cm to radiation from a medium pressure mercury
arc lamp (80 w per cm) for the indicated time. The results obtained
2 are also shown in Table I.
1300307
- 25 -
TABLE I
Example Complex
No. Name Amount on Irradiation Result
weight of time
resin
. _
1 Tricarbonyl(cyclohexa- . .
1,3-dienylium)iron 2% 2 mlnutes Fllm sllghtly
tetrafluoroborate tacky, becomes
tack-free on
standing
2 Tricarbonyl(l-methyl- Film tack-
cyclohexa-2,4-dienyl- free
ium)iron hexafluoro- 3% 2 minutes
phosphate
3 Tricarbonyl(l-methyl-
4-methoxycyclohexa-2,4- 2% 2 minutes Film tack-
dienylium)iron hexa- free
fluorophosphate
4 Tricarbonyl(2-methoxy-
bicyclo C4.4.0~ deca- 3% 40 seconds Film tack-
2,4-dienylium)iron free
hexafluorophosphate
13~
- 27 -
Tricarbonyl(l-~acetoxy-
methyl)-2-(methoxy- 4%2 minutes Film slightly
carbonylacetoxy)ethyl- tacky, becomes
cyclohexa-2,4-dienylium)- tack-free on
iron hexafluorophosphate standing
:
6 Tricarbonyl(l-(methoxy-
carbonyl)-4-methoxycyclo- 3% 2 minutes Film slightly
hexa-2,4-dienylium)iron tacky, becomes
tetrafluoroborate
tack-free on
__ _ _ _ _ _ __ standing
_ None _ 20 No effect
minutes
EXAMPLES 7-8
The procedure of Examples 1 to 6 is repeated, with Epoxide
Resin II. The results obtained are shown in Table II.
TABLE II
Example Complex
No. NameAmount on
weight of time Result
_ _ __ _ e sin
7 ¦ Tricarbonyl(l-methyl- Film slightly
cyclohexa-2,4-dienyl- 3% 2 minutes y, e
ium)iron hexafluoro- standing
phosphate
_ _ _ __ ~ _ _
8 Tricarbonyl(2-methoxy-
bicyclo C4.4.0] deca- 3% 5 seconds Film tack-
2,4-dienylium)iron hexa- free
fluorophosphate
13()0307
- 28 -
EXAMPLE 9
A mixture comprising 5 grams of Epoxide Resin II, 0.2 g of
1r-l-methyl-5,6,7,8-tetrahydronaphthalenetricarbonyliron
hexafluorophosphate, and 1 drop of a commercially available flow
control agent (a fluorocarbon~ is applied to tinplate as in Examples
1 to 6. The film becomes tack-free after irradiation for 12 seconds.
After the film has been heated to 100C for 10 minutes it
withstands 12-13 rubs in the ~tandard acetone rub test for solvent
resistance, in which a cotton wool swab soaked in acetone is
rubbed across the surface.
EXAMPLE 10
Epoxide Resin III (49.38 parts~ is dissolYed in a mixture
of acetone (14.81 parts) and ethyl methyl ketone (34.57 parts).
To this solution is added ~-toluenetricarbonylmanganese
hexafluorophosphate ~1.5 parts), and the homogeneous solution
is spread on a copper-coated plate of epoxide resin - glass
laminate by means of a 24 ~ roller coater (i.e., the wet film
is 24 ~ thick). The coating, after being dried at 75 C for
20 minutes, isirradiated with a 5000 w metal halide lamp for
3 minutes through a Stouffer 21 step sensitivity guide. The
plate is heated for 3 minutes at 80C and then developed with
ethyl methyl ketone. Etching in 50~ ferric chloride solution
yields a No. 2 step image.
EXAMPLES 11-13
These Examples, set out in Table III, illustrate the use
13~03~
of photoinitiators in conjunction wqth a complex of formula I to
photopolymerise Qn epoxide resin. The procedure of Examples 1-6
is followed. In Example 11 Epoxide Resin II i~ used, in
Examples 12 and 13 Epoxide Resin I is used.
13()~3~
` 3()
= .~ .
5 ~1
V ~ ~
c ~ r
P~ 8 .~
8 ~ N
~1
~1 c4-~ ~ ! ~ 1
~ I
X
_~ ~
~- o I a~ o I ~ ?~
O ra ~ J~
~ a~ C ~,C
e o c~ 4 e ~ ~ ~ e ~ ~ ~
~I O~r~ o ~ o _~ r o o ~ ; o o
,~ ~ e ~ _, ~ e -~ _ O ~
?~ ~ O ~ O p~ O ~ ~ O
.n~ P. ~ ~ ?. e~ ~
~ ~ X ,~X ~ _I
a~ ~ t~ a~ ~ aJ ~t~ o ~ u~ t~ O ?~ u~
Z h r~ i a~ J~ a~ X ~ a X
E~ ~ ~ r! E~ ,n ~ ~ E~
.
Z
i3~J~3~)7
-- 31 --
g ~E ~n 0
~1 ~ ~ 'O ~
ra O I g g
. ~.v V V
tc E ca E ~r ~
'C~
.c~ C ~
~'C
~ e ,.
~ ~ '
O
~ a ~ ~ ~ ~ ~
X .
:~ ~ l I
',
O x~ ê O O ~ e O
.
O ~ O _I
e V P C X V ~ C x
Z ~, O~ ,,~ ~~ ~n.,l a
. ~ 3
E ~ ~
1300307
- 32 -
In Examples 14 to 23 an epoxide resin is photopolymerised and
subsequently heat cured.
EXAMPLE 14
A mixture comprising 5 parts of Epoxide Resin I, 0.2 part
of tricarbonyl(l-ethyl-4-isopropoxycyclohexa-2,4-dienylium)iron
hexafluorophosphate, and 0.2 part of boron trichloride-
trimethylamine complex is applied as a coating 6 um thick
onto tinplate and irradiated with a lamp (80 w per cm) at a
distance of 20 cm for 50 seconds. The film is tack-free. On
the coating being rubbed with a cotton wool swab soaked in
acetone it is attacked after two rubs. Next, the plate is
heated at 150C for 1 hour, when the coating has appreciably
greater resistance to the solvent, withstanding 13 such rubs.
EXAMPLE-15
A mixture comprising Epoxide Resin I aoo parts), ~-methoxy-
benzenetricarbonylmanganese hexafluorophosphate (3 parts), and
acetone (3 parts) is applied as a coating 8 um thick on tinplate.
The coating is irradiated using a medium pressure mercury arc
lamp (80 w per cm) at a distance of 20 cm and then heated in an
oven at 120C. Irradiation for 30 seconds followed by heating
for 10 minutes produces a hard, tack-free film.
EXAMPLE 16
;
The procedure of Example 15 is repeated, replacing the
hexafluorophosphate with ~-hexyloxybenzenetricarbonylmanganese
13~0307
- 33 ~
hexafluorophosphate (3 parts). Irradiation of the coating for 30
seconds followed ~y heating for 3 minutes produces a tack-free film.
EXAMPLE 17
The procedure of Example 15 is repeated, replacing the
hexafluorophosphate with ~-hexylbenzenetricarbonylmanganese
hexafluorophosphate (3 parts2. Irradiation of the coating for
20 seconds followed by heating for 1 minute gives a tack-free
film.
EXAMPLE 18
The procedure of Example 15 is repeated using a mixture
of Epoxide Resin I (50 parts2~ Epoxide Resin II (30 parts2,
Epoxide Resin IV (20 parts), ~-hexylbenzenetricarbonylmanganese
hexafluorophosphate (3 parts) and acetone (3 parts) in place
of the mixture used in Example 15. Irradiation of the coating
for 10 seconds followed by heating for 1 minute gives a hard
tack-free film.
EXAMPLE 19
The procedure of Example 18 is repeated, replacing
the hexafluorophosphate with an equal weight of ~-hexyloxy~
benzenetricarbonylmanganese hexafluorophosphate. Irradiation
for 10 seconds followed by heating for 2 minutes produces a
hard, tack-free film.
EXAMPLE 20
The procedure of Example 18 is repeated, replacing the
hexafluorophosphate with an equal amount of ~-methoxybenzene-
13VO~
tricarbonylmanganese hexafluorophosphate. Irradiation for lO
seconds followed by heating for 2 minutes produces a tack-free
film.
EXAMPLE 21
A mixture of Epoxide Resin V (60 parts2, Epoxide Resin II
(40 parts), ~-methoxybenzenetricarbonylmanganese hexafluorophosphate
(3 parts) and acetone ~5 parts2 is applied as a coating 8 ~m
thick on tinplate. The coating is irradiated using a medium
pressure mercury lamp (80 w per cm~ at a distance of 20 cm and
then heated in an oven at 100C. Irradiation for 20 seconds
followed by heating for 3 minutes results in a tack-free film.
EXAMPLE 22
Example 21 i8 repeated, replacing the hexafluorophosphate
with an equal weight of ~-hexyloxybenzenetricarbonylmanganese
hexafluorophosphate. Irradiation for 20 seconds followed by
heating for 35 seconds results in a tack-free film.
EXAMPLE 23
The procedure of Example 21 is repeated, replacing the
hexafluorophosphate with an equal weight of ~-hexylbenzenetricarbonyl-
manganese hexafluorophosphate. Irradiation for 10 seconds followed
by heating for 1 minute produces a hard, tack-free film.
