POLYMERIZABLE ACRYLIC COMPOSITIONS HAVING VINYL ETHER ADDITIVES

COMPOSITIONS ACRYLIQUES POLYMERISABLES RENFERMANT DES ADDITIFS A BASE D'OXYDE DE VINYLE

English Abstract

ABSTRACT OF THE DISCLOSURE
Polymerization of acid activated compositions of
acrylic monomers, peroxy initiators and ferrocene
derivatives is inhibited by addition of 0.5-20% of a vinyl
ether monomer. Bulk compositions activated by addition of a
strong acid can be provided with a desired polymerization
induction time directly related to the concentration of the
vinyl ether. Compositions containing compounds which
decompose to a strong acid upon exposure to actinic
radiation, thereby activating polymerization, have increased
shelf lives when vinyl ethers are included therein. The use
of vinyl ether monomers having a functionality of two or
more also provides increased adhesive bond strength after
curing.

Claims

- 11 -
CLAIMS
1. In a curable composition activatible by a strong acid
comprising an acrylic monomer, a peroxy initiator and a
ferrocene compound the improvement comprising that the
composition further comprises from 0.5-20% of a vinyl
ether monomer.
2. An activated composition as in Claim 1 further comprising
said strong acid.
3. A cured composition as in Claim 2.
4. A composition as in Claim 2, wherein said strong acid
is selected from saccharin, perchloric acid, sulfonic
acids, phosphonic acids, maleic acid, acetylene carboxylic
acid, acetylene dicarboxylic acid or malonic acid.
5. A composition as in Claim 1 further comprising a
compound which-decomposes upon exposure to actinic
radiation to release a strong acid.
6. A composition as in Claim 5 wherein the radiation
decomposible compound is a salt of a complex halogenide
having the formula [A]?[MXe]-(e-f) where A is
a cation selected from the group consisting of
iodonium, sulfonium, thiopyrylium and diazonium
cations, M is a metalloid, X is a halogen radical,
d=e-f, f=the valence of M and is an integer equal to
from 2 to 7 inclusive, e is greater than f and is an
integer having a value up to 8.
7. The composition of Claim 1 wherein the peroxy initiator
is an organic hydroperoxide.

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8. The composition of Claim 7 wherein the organic hydroperoxide
is present at levels of between 0.1 and 10% by weight
of the composition.
9. The composition of Claim 7 wherein the organic hydroperoxide
is selected from cumene hydroperoxide, t-butyl hydroperoxide
and methylethylketone hydroperoxide.
10. The composition of Claim 1 wherein the ferrocene
compound is selected from ferrocene, t-octyl ferrocene,
acetyl ferrocene, benzoyl ferrocene, hydroxyethyl
ferrocene, 1,1'-dibutyl ferrocene, n-butyl ferrocene
and ferrocene polymers.
11. The composition of Claim 1 wherein the vinyl ether
monomer is selected from the group consisting of
ketene acetals and monomers of the formulae:
(CH2=CH-O-CH2)n-G; (CH2=CH-O-C6H4)n-G;
(CH2=CH-O-CR1=CR2)n-G; or
(CH2=CH-O-C?C)n-G, where n is an integer greater
than or equal to one; G is a mono or multivalent
radical free of groups which interfere with cationic
or free radical polymerization; and R1 and R2 are
selected from H, hydrocarbonyl or halogen substituted
hydrocarbonyl.

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12. The composition of Claim 11 wherein n is greater than
1.
13. The composition of Claim 11 wherein the vinyl ether is
selected from n-butyl vinyl ether, 1,4-butanediol
divinyl ether, 2-chloroethyl vinyl ether and ethyl
vinyl ether.
14. A process of sealing or bonding substrates which
comprises applying to at least one of said substrates
an activated composition as in Claim 2, and joining
said substrates until said composition has cured
sufficiently to bond or seal said substrates.
15. The process of Claim 14 wherein said applying step
comprises: (a) applying a composition comprising said
acrylic monomer, peroxy initiator, ferrocene compound,
and vinyl ether monomer ingredients, and a compound
which decomposes upon exposure to actinic radiation to
release a strong acid, to said substrate; and (b)
irradiating said composition to release the strong
acid.

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16. A method as in Claim 14 wherein the applying step
comprises applying to at least one of said substrates a
primer comprising at least one of said strong acid or
said ferrocene ingredients and subsequently applying to
at least one of said substrates a composition comprising
the remaining ingredients of said activated composition.
17. A method as in Claim 14 wherein said composition is
activated in bulk prior to said applying step.
18. The composition of Claim 11 wherein the vinyl ether
monomer is a ketene acetal of the formula
<IMG>
wherein n and G are as defined in Claim 11; R3 is
hydrocarbonyl or halogen substituted hydrocarbonyl
and Y is a hydrocarbonyl group having between 1 and 5
carbon atoms.

Description

- 2 -
Background of The Invention
The present invention pertains to acrylic monomer
compositions which utilize a ferrocene/peroxy initiator/strong
acid initiation system. As used herein, the term acrylic
monomers refers to compounds having groups of the formula
CH2=C(R)-C(=0)-0- where R is ~ or alkyl.
In U.S. Patent 3,753,927, there are described promoter
systems for peroxide cured unsaturated polyester resins
which include certain ferrocene compounds having carbonyl
containing substituents.
In U.S. Patent 3,855,040 to Malofsky, it is disclosed
that combinations of a ferrocene compound, a strong acid and
a peroxy compound are effective initiators of acrylic
monomer compositions.
In U.S. Patent 4,076,742, anaerobic compositions
utilizing an oligocarbonate acrylate, ben~oyl peroxide,
ferrocene and a specified inhibitor are described.
In EP published application.0134677 published
March 20, 1985, there are described radiation activatable
adhesive compositions comprising an acrylic monomer, a
peroxy initiator, a ferrocene and a compound which decomposes
on exposure to actinic radiation to release a strong acid,
thereby activating anaerobic cure of the system.
Summary of The_Invention
The present invention-is an improvement in the acid
activated acrylic monomer/ferrocene/peroxy initiator systems
of U.S. Patents 3,855,040 and EP 0134677.
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Specifically, the present invention is an activated
composition comprising (a) an acrylate monomer, (b) a
peroxy free radical initiator, (c) a ferrocene compound,
and (d) 0.5-20% by weight of the curable composition
ingredients of a vinyl ether monomer.
The vinyl ether in the inventive compositions acts
as a novel cure inhibitor which provides controllable
pot life to systems activated by added acid as in U.S.
Patent 3,855,040 and increases the stability of light
activated compositions. The use of difunctional or poly-
functional vinyl ethers in the inventive compositions
provides increased adhesive bond strengths after curing.
Detailed Description of The Invention
Specific examples of the acrylic monomers utilizable
in the inventive compositions include the acrylic esters
as described in columns 3 and 4 of U.S. Patents 3,855,040,
i.e., di- and poly-(meth)acrylate (i.e., acrylate and
methacrylate) esters and monofunctional (meth)acrylate
esters having a polar group selected from labile hydrogen,
heterocyclic ring, hydroxy, amino, cyano, and halogen
groups; (meth)acrylate functional urethane block copolymers
such as described in U.S. Patents 4,018,851, 4,295,909
and 4,309,526, and acrylic functional silicone resins.
Examples of peroxy initiators usable in the inventive
compositions include the peroxy compounds mentioned at
columns 4 ana 5 of U.S. Patent 3,855,040. Preferred
peroxy compounds are organic hydroperoxides, such as cumene
hydroperoxide, t-butyl hydroperoxide and methyl ethyl
Xetone hydroperoxide. The peroxy initiators are recommended
to be used at levels between about 0.1% and 10% by weight,
preferably between about 0.5% and 5% by weight of the
total composi~ion.
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The ferrocene compounds usable i.n the inventive compositions
are also described in U.S. Patent 3,~5.~,040 and include
ferrocene (dicyclopentadienyl iron) and ferrocene
derivatives having substituents on one or both
cyclopentadienyl rings, such as acetyl ferrocene, benzoyl
ferrocene, hydroxyethyl ferrocene, butyl ferrocene,
1,1-dibutyl ferrocene and polymers having ferrocene moieties
incorporated therein, such as the polymer described at
column 12, lines 3 et seq of U.S. Patent 3,855,040.
The acid activators may be strong acids, preferably an
acid having a small pKa less than about 3. n, preferably less
than 2.0, and most pxeferably 1.5 or less. The acid should
be reasonably soluble and the remainder of the composition
to facilitate distribution throughout the polymerizable
mixture. While not absolutely essential, it is preferably
for the acid to be an organic aci.d. Typical examples are
sulfonic acids such as toluene sulfonic acid, nitrotoluene
sulfonic acid and propane sulfonic acid; dichloro- and
trichloroacetic acids; phosphonic acids such as benzene
phosphonic acid. Other useful acids include acetic, maleic,
malonic, acetylene carbox~lic, and acetylene dicarboxylic
acids and saccharin.
The acid activator may also be formed in situ by
radiation induced decomposition of a compound which decomposes
to form a strong acid. Such compounds include salts of a
complex halogenide having the formula
[ ] [ ~-(e-f)
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where A is a cation selected from the group consisting of
iodonium sulfonium, thiopyrylium and diazor.ium cations, M is
a metalloid, and X is a halogen radical, d equals e minus
f, f equals the valance of M and is an integer equal to from
2 to 7 inclusive, e is greater than f and is an integer
having a value up to 8. Suitable compounds are described in
more detail in the aforementioned copending application
515,540. Examples include di-p-tolyl iodonium hexa-
fluorophosphate, diphenyl iodonium hexafluorophosphate,
diphenyl iodonium hexafluoroarsenate and WE 1014 (trademark
of General Electric), a commercially available sulfonium
salt of a complex halogenide. The salts of the complex
halogenides may be incorporated into the adhesive compositions
of the present invention at concentrations of about 0.05 to
about 15.0% by weight and preferably about 0.075 to about
3.0% by weight of the total composition.
The vinyl ether additives which are present in the
invPntive compositions at levels of between 0.5 and 20% by
weight of the composition may be represented by the
formulas: (CH2=CH-0-CH2)n-G; (CH2=CH-0-C6H~)n G;
(CH2=CH-0-CR =CR )n~G; or (CH2=CH-0-C_C)nG, or ketene
acetals such as those of the formulas:
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CH2=C- ~ G or ~CH2 ~ Of ~
where G is a mono or multivalent radical free of groups,
such as amino, substituted amino or phenol which interfere
with cationic or free radical polymerization; n is an
integer greater than or equal to one; Rl and R2 are selected
from H, alkyl, substituted alkyl, aryl, and substituted
aryl; R3 is selected from alkylj substituted alkyl, aryl and
substituted aryl; and Y is a hydrocarbonyl group of 1~5
carbon atoms. Polyfunctional vinyl ethers are preferred.
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Exemplary of the polyfunctional vinyl ethers that may
be employed in the practice of the present invention there
may be given n-butyl vinyl ether; 1,4-butanediol divinyl
ether; 2-chloroethyl vinyl ether and ethyl vinyl ether.
The compositions of the present invention are useful
for sealing or bonding substrates. Exemplary of the
methods by which these compositions may be employed for
said processes there may be given (a) applying the
composition to the substrate and irradiating the same, (b)
applying to at least one of the substrates at least one of
the strong acids or ferrocene ingredients as a primer and
subsequently applying to at least one of the substrates a
composition comp~ising the remaining ingredients of the
instant compositions and thereafter irradiatir.g the same
and (c) activating the composition prior to applying the
same to the substrate.
; The invention is illustrated by the following nonlimiting
examples.
Example 1
A formulation was prepared consisting of 40.72 grams of
polyethylene glycol dimethacrylate tthe dimethacrylate ester
of polyethylene glycol of molecular weight 200), ~.493 grams
of ferrocene, and 1.058 grams of cumene hydroperoxoide.
Aliquots of 3.75 grams of the above formulation were poured
into three 12 x 75mm Pyrex test tubes. To the first test
tube 4 drops from a Pasteur pipette of a 0.1 ~ solution of
perchloric acid in glacial acetic acid were added. ;~
Pol~erization of the cont nts occurred in less than two
minutes. To the second tu`)e 0.15 grams of n-butyl vinyl
ether was addad and mixed thoroughly; 4 drops of a O.lN
; solution of perchloric acid in glacial acetic acid were then
added. Polymerization of the contents occurred in 5
minutes. To the third tube 0.33 grams of n-butyl vinyl
ether was added and mixed thoroughly, 4 drops of a O.lN
solution of ~erchloric acid in glacial acetic acid were then
added. Polymerization of the contents occurred in 15-30
minutes
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A formulation was prepared consisting of 40.3 grams of
polyethylene glycol dimethacrylate (the diemthacrylate ester
of polyethylene glycol of molecular weight 200), 0.34 grams
of tert-octyl ferrocene and 0.554 grams of cumene hydroperoxide.
Aliquots of 3.75 grams of the above formulation were poured
into two 12mm x 75mm Pyrex test tubes. To the first test
tube 4 drops from a Pasteur pipette of a O.lN solution of
perchloric acid in glacial ac:etic acid were added.
Polymeri~ation of the contents occurred in 1-2 minutes. To
the second tube 0.34 grams of n-butyl vinyl ether was added
and mixed thoroughly; 4 drops of a O.lN solution of
perchloric acid in glacial acetic acid were then added.
Polymerization of the contents occurred in 5-10 minutes.
Example 3
A formulation was prepared consisting of 10.0 grams of
hydroxypropyl methacrylate; 36.G6 grams of a mixture of two
related urethane-acrylate resins comprising: i) a block
copolymer prepared by first reacting a flexible polymeric
methylene ether diol with a molar excess of diisocyanate
such as toluene diisocyanate so that the product had an -NCO
group at each end of the diol, the product~of this reaction
being reacted with a molar equivalence of a hydroxyalkyl
methacrylate to form a flexible dimethacrylate block copolymer
as disclosed in Baccei, U.S. 4,309,526 and ii) a urethane-
acrylate resin of the type disclosed in U.S. 3,425,988;~1.0
gram of cumene hydroperoxide; O.Q15 grams of tetra sodium
ethylenediamine tetraacetate; 0.46 grams of~ferrocene; and
0.15 grams of di-p-tolyl iodonium hexafluorophosphate. This
formulation will be referred to as Formulation ~.
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A second formulation was prepared in which 30.0 ~rams
of formulation A was mixed with 0.5 grams of 1,4-butanediol
divinyl ether. This formulation will he referred to as
Formulation E.
A third formulation was prepared in which 30.0 grams of
formulation A was mixed with 1.5 grams of 1,4-butanediol
divinyl ether. This formualation will be referred to as
Formulation C.
A fourth formulation was prepared in which 30.0 grams
of formulation A was mixed w:ith 3.0 grams of 1,4-butanediol
divinyl ether. This formulation will be referred to as
Formulation D.
Pairs of mild steel grit blasted lapshears, 2 centimeters
wide, were coated in one face with the formulations outlined
above and irradiated at 50 mw/cm2 (measured at 365 nml for
30 seconds. The coated surfaces of each pair were firmly
placed in contact either immediately after the cessation of
irradiation or 5 minutes after the cessation of irradiation.
In each case a 0.5 inch overlap in the length direction of
the lapshear was prepared and the bonds left for 24 hours at
room temperature to cure. The ~ond strengths were measured
in the tensile shear mode, using conventional tensile
testing equipment~. The results are~summarized in Table I.
TABLE I
Delay Before Average Tensile
FormulationAssembly, Min.Strensth, _aN/om
A 0 71
A 5 55
B 0 27
B 5 127
C 0 25
C S 106
D 0 137
D 5 166
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The data in Table I indicates that formulations containing
the divinyl ether show improvementC in hond strengths
corresponding to increasing vinyl ether content.
Example 4
A formulation identical to Formulation A described in
Example 3 was prepared with the exceptions that the amount
of 2,6-di-tert-butyl~4-methyl phenol was reduced from 0.15
grams to 0.05 grams and the amount of di-p-tolyl iodonium
hexafluororphosphate was increased from 0.15 grams to 1.5
grams. This formulation will be referred to as Formulation
E.
A second formulation was prepared in which 10.0 grams
of Formulation E was mixed with 1.0 gram of 1,4-butanediol
divinyl ether. This formulation will be referred to as
Formulation F.
Two grams of each formulation were poured into ~eparate
12mm by 75mm Pyrex test tuhes and heated at 82C. The time
taken for gelation to occur was meaeured as 24 minutes for
Formulation E and 104 minutes for Formulation F. Both
formulations were useful as light-activated anaerobic
adhesives.
ExamDle 5
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A formulation identical to Formulation A described~in
Example 3 was prepared with the exceptions that the amount
of 2,6-di-tert-butyl-4-methyl phenol was reduced from O.lS
grams to 0.05 grams and the di-p-tolyl iodonium hexafluoro-
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phosphate was replaced by 0.142 grams of UVE 1014 (trademark
of General Electric), a commercially availahle sulfonium
salt of a complex halogenide. This formulation will be
referred to as Formulation G.
A second formulation was prepared in which 10.0 grams
of Formulation G was mixed with l.0 gram of 1,4-butanediol
divinyl ether. This formulation will be referred to as
Formulation H.
Preparation, irradiation, assembly and testing of bonds
was conducted as described in Example 3 with the exception
that irradiation was conducted for 60 seconds at an
intensity of 25 mw/cm2. Results are summarized in Table II.
TAELE II
Delay Before Average Tensile2
Formulation Assembly, Min. Strenath, DaN/cm
G 0 104
G 5 91
H 0 193
H 5 176
The stabilities of the formulation were measured as
outlined in Example 4. Formulation G had a gel time of 180
minutes; Formulation H had a gel t1me of 245 minutes.~
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