Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
2002-03-25
2004-12-21
Copenheaver, Blaine (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S327000, C526S328500, C526S329700
Reexamination Certificate
active
06833041
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to the use of free-radically polymerized, UV-crosslinkable addition polymers which consist to the extent of at least 50% by weight of C
2
to C
18
alkyl(meth)acrylates as adhesives for the bonding of carriers coated with the polymer on substrates, wherein from 0.1 to 30% by weight of the monomers of which said polymer is composed are monomers A without carboxylic acid or carboxylic anhydride groups and with a water solubility of more than 5 g of monomers per liter of water and said substrates are moist substrates, especially refrigerated substrates.
BACKGROUND OF THE INVENTION
UV-crosslinkable polymers and their use as adhesives—as hot-melt pressure-sensitive adhesives, for example—are known from DE-A-2 411 169, EP-A-246 848, DE-A-4 037 079 or DE-A-3 844 444, for example.
These adhesives have not been used to date for moist substrates, especially refrigerated substrates.
For producing labels for refrigerated product it is normal to use block polymers of the styrene-isoprene-styrene or styrene-butadiene-styrene type. A general disadvantage of these block copolymers lies in their softness, which leads to difficulties in the course of processing and use.
There is a desire for alternative polymers as adhesives for moist, refrigerated substrates.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide alternative polymers for such a use.
We have found that this object is achieved by the use defined at the outset.
For crosslinking with UV light, the addition polymer may contain a photoinitiator. The photoinitiator may be attached to the polymer but may also be unattached and merely mixed with the polymer.
Customary photoinitiators that can be added to the polymer are, for example, acetophenone, benzoin ethers, benzil dialkyl ketals, or derivatives thereof.
The amount of photoinitiator mixed in is preferably from 0.05 to 10 parts by weight, with particular preference from 0.1 to 2 parts by weight, per 100 parts by weight of polymer.
Through irradiation with high-energy light, especially UV light, the photoinitiator or photoinitiator group brings about a crosslinking of the polymer, preferably by means of a chemical grafting reaction of the photoinitiator group with a spatially adjacent polymer chain. Crosslinking can be effected in particular by inserting a carbonyl group of the photoinitiator into an adjacent C—H bond to form a —C—C—O—H grouping.
The wavelength range within which the photoinitiator group can be activated, i.e., that in which the principal absorption band of the photoinitiator group lies, is preferably from 200 to 450 nm, with particular preference from 250 to 350 nm, with very particular preference from 250 to 280 nm.
Preferably, the photoinitiator is attached to the polymer.
The polymer is obtainable by free-radical addition polymerization from ethylenically unsaturated free-radically polymerizable compounds.
In the preferred case where the photoinitiator is attached to the polymer an ethylenically unsaturated compound having a photoinitiator group is preferably incorporated by copolymerization.
REFERENCES:
patent: 4737559 (1988-04-01), Kellen et al.
patent: 24 11 169 (1974-09-01), None
patent: 38 44 444 (1990-08-01), None
patent: 40 37 079 (1992-05-01), None
patent: 0 246 848 (1987-11-01), None
patent: 03 237181 (1991-10-01), None
patent: 06 158006 (1994-06-01), None
patent: 93 13148 (1993-07-01), None
Barwich Jürgen
Düsterwald Uwe
Fink Ralf
Meyer-Roscher Bernd
Schumacher Karl-Heinz
BASF - Aktiengesellschaft
Copenheaver Blaine
Haran John T.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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