Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2001-03-16
2003-04-22
Zalukaeva, Tatyana (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C525S049000, C525S309000, C526S328000, C526S307500, C526S218100, C526S219500, C526S204000, C526S301000, C526S314000, C526S318420, C526S318430, C526S320000, C526S090000
Reexamination Certificate
active
06552140
ABSTRACT:
TECHNICAL FIELD
This invention relates to air-activatable polymerisable compositions and their use. The compositions of the invention include air/moisture activatable compositions and dual curing compositions with secondary air-activatable cures. The compositions are suitable for use as one-component systems or in certain cases as two-component systems for forming polymers. The compositions are useful in the field of adhesives, sealants, surface coatings, moulding resins and composite matrices, for example.
BACKGROUND ART
Free radical polymerizable compositions are disclosed in EP-A-O 356 875 of Henkel KGA. These comprise ethylenically unsaturated, polymerizable compounds together with an activator system which can be initiated by oxygen and water, comprising an N-alkyl-substituted tert.arylamine with at least one aliphatic CH bond in the alpha position, a metal compound generally used for accelerating the drying of unsaturated oil and which is at least partially soluble in the composition, and a compound of a weakly acidic carboxylic acid having a pKa value of no less than about 0.9, which can be hydrolyzed to a free carboxylic acid on contact with moisture.
The N-alkyl-substituted tert.-arylamines correspond in particular to the general formula:
in which R
1′
is an optionally substituted aryl radical, more especially an optionally alkyl-substituted phenyl radical, R
2′
has the same meaning as R
1′
or is an optionally substituted, linear or branched alkyl radical and R
3′
is a linear or branched alkyl radical which may be substituted, but contains at least one hydrogen atom in the alpha-position to the nitrogen. One particular compound used by way of example is N,N-dimethyl-p-toluidine having the formula:
These compositions depend on the action of both water and oxygen to effect a cure reaction. As such their formulations are very dependant on humidity conditions.
WO 91/10687-A of Henkel KGaA discloses air-activatable adhesive compositions comprising mixtures of free-radically polymerisable unsaturated olefinic compounds, and hydrazone compounds prepared and stored under anaerobic conditions. The hydrazones may be alkyl, cycloalkyl and/or aryl hydrazone(s) of aldehyde(s) and/or ketone(s) and are claimed to react with air to form hydroperoxides useful as polymerisation initiators. The one component compositions are stable in the absence of air.
WO 93/01218 of Henkel KGaA also describes compositions containing hydrazones as activators.
EP-A-0 502 733 (U.S. Pat. Nos. 5,506,326 or 5,610,251) of Loctite (Ireland) Limited (the contents of which are incorporated herein by reference) describes a one-part air-activatable polymerisable composition comprising:
(a) at least one free-radically polymerisable monomer, and
(b) an activator system for effective polymerisation of the free-radically polymerisable monomer, said activator system comprising at least one auto-oxidisable compound of a formula which includes the structure I:
where x is 0 or 1, and where the lines representing unfilled valencies indicate
bonds to carbon, hydrogen or hetero atoms,
alone or in combination with a weak acid;
with the proviso that:
when x=0, the nitrogen atom in structure I is not bonded to a second nitrogen atom;
and when x=1 there is a structure I in the compound in which the >C═C< moiety does not form part of a phenyl ring;
with the proviso that the composition does not contain a peroxide, or a peroxide precursor which produces peroxide in the absence of air or any ingredient which is a significant source of radicals in the absence of air.
Preferred auto-oxidisable compounds are selected from the group consisting of partially hydrogenated pyridines, condensation products of cyclic ketones and ureas, Schiff's bases, indoles, pyrroles, imidazoles, piperazines, carbazoles, tetrahydroquinolines, and substituted derivatives thereof, particularly dihydropyridines.
The presence of a weak acid is generally preferred in order to achieve a satisfactory rate of auto-oxidation for the partially hydrogenated pyridines. The majority of the working examples using dihydropyridines in EP-A-0 502 733 have acrylic acid in the formulation. Other acids used are methacrylic acid, trichloroacetic acid, cyanoacetic acid, salicylic acid, benzoic acid, acetic acid and saccharin.
The composition may also contain a soluble ionic salt, particularly a cobalt or iron salt.
The compositions as described in EP-A-0 502 733 are stable on storage in the absence of air, are activated by exposure to air, and will then cure in either the presence or absence of air.
EP-A-0 611 813 of Loctite (Ireland) Limited describes air-activatable polymerisable compositions containing onium salts and not requiring the presence of a weak acid. WO 90/02142 of Henkel KGaA describes further radical polymerisable compositions having an auto-oxidation activator system comprising an N-alkyl substituted tertiary arylamine, a metal drier compound and a weakly acidic compound.
WO 95/07304 of Henkel KGaA also describes air-activatable compositions containing certain furanones as initiators, especially optionally substituted 2,4,5-triphenylfuran-3-one. Air-activatable compositions must be stable on storage in the absence of air (i.e. under anaerobic conditions). They are activated by exposure to air and then cure in either the presence or absence of air.
It would be desirable to provide additional auto-oxidisable compounds (autoxes) with properties different from those already described.
It would be desirable to provide dual curing compositions with a secondary air-activated cure, the primary cure being either a UV or visible light initiated cure, or another air-activated cure. Dual curing compositions are particularly useful in the electronic field to overcome the problem of “shadow” which can occur with UV or light curing, i.e. part of the electronic component shields the polymerisable composition during exposure to the UV or visible light, so that a secondary cure is required to ensure polymerisation throughout the composition.
Von Helmut Bredereck et al.,
Die Makromoleculare Chemie
, 92 (1966), 70-90 describes polymerization initiators which are compounds of the general formula A—CH(R)—B wherein A and B means electron attracting groups, and R is an H atom or an alkyl group. These compounds initiate the polymerization of monomers like methyl methacrylate, acrylonitrile, styrene and vinyl acetate in the presence of Cu
++
, Cl
−
and oxygen or peroxides. The ═CHR group may be part of a carbocyclic or heterocyclic ring, like cyclic &bgr;-oxocarbonic esters, &bgr;-oxolactones, &bgr;-diketones, pyrazolones or barbituric acids. The start of polymerisation is explained as an auto-oxidation of the active CH-groups to the hydroperoxide, which starts polymerization. However this publication describes the use of copper catalysts only and makes no mention of the use of acids or latent acids.
GB 1,293,209 of Bayer AG describes polyester moulding and coating masses of unsaturated polyesters and copolymerisable ethylenically unsaturated compounds (e.g. acrylic and methacrylic compounds) which contain hydroperoxides as initiators and also contain soluble cobalt compounds as accelerators, and which contain, as additional accelerators, compounds which are derived from cyclopentanone and which are in a keto/enol equilibrium and which correspond to the formulae:
in which X is oxygen and Y is an acyl, carbocyclic acid ester, or N-substituted or unsubstituted carboxamide group.
However there is no teaching that the beta diketones included within the disclosure of the Bayer Patent would be active as autoxes and capable of initiating free radical polymerisation of monomers on contact with air.
It would also be desirable to provide additional autoxes with properties different from those already described.
SUMMARY OF THE INVENTION
More specifically, the present invention provides an air-activatable polymerisable composition comprising:
a) at least one free-radically polymerisable monomer,
b) an activator s
Barnes Rory B.
Kneafsey Brendan J.
Bauman Steven C.
Loctite (R&D) Limited
Zalukaeva Tatyana
LandOfFree
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