Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
1998-09-21
2001-06-05
Seidleck, James J. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Compositions to be polymerized by wave energy wherein said...
C522S003000, C522S181000, C522S120000, C522S121000, C522S910000, C427S516000, C427S517000, C427S513000, C427S208400, C427S508000, C427S496000, C427S505000, C428S333000, C428S332000, C428S339000, C428S343000, C156S060000, C156S272200, C156S275100, C156S275300, C156S307100, C156S325000, C156S332000
Reexamination Certificate
active
06242504
ABSTRACT:
The invention relates to a method of crosslinking pressure-sensitive adhesive films by controlled-dose irradiation, especially with UV light.
With conventional pressure-sensitive adhesives (PSAs) based on acrylate, SBC or NR [SBC=styrene block copolymers such as SIS (styrene-isoprene-styrene) or SBS (styrene-butadiene-styrene), or SBR (styrene-butadiene rubber); NR=nitrile rubber=butadiene-acrylonitrile rubber] applied as hotmelts, dispersions or in solvent, the PSA properties can be influenced by adding tackifiers. These include both tackifying resins and plasticizers, such as oils.
Modem PSAs are based on solvent-free hotmelt PSAs which are applied as a film to a substrate and then can be crosslinked by irradiation, especially with UV light. Adhesives of this kind have been described, for example, by Auchter, Barwich, Rehmer and Jäger in the article “UV-vernetzbare Acrylat-Schmelzhaftklebstoffe” [UV-crosslinkable acrylate hotmelt pressure-sensitive adhesives] in “kleben & dichten” 37 (1993), pages 14 to 20 and in EP-A 377 199 and 448 741. The base polymer is prepared in such a way that it is close to what is known as the gel point. The polymer is sensitized to high-energy radiation, especially UV-A radiation, with the aid of photoinitiators, which are either mixed in or attached chemically. Controlled exposure to a defined UV dose enables the degree of crosslinking of the polymer to be adjusted. It is this degree of crosslinking which is the critical determinant of the ultimate properties of the PSA. For instance, using a single polymer it is possible merely by irradiation with different UV doses to produce a very tacky adhesive label which adheres even to moist substrates or an adhesive label which has crosslinked so much that it can be redetached without residue from any surface.
Such ultimate properties can be adjusted in principle as described above. Irradiation is carried out solely with the level of UV light required to establish the desired properties. Otherwise, “overexposure” would drastically alter the properties of the product.
Optimum PSA properties, however, which are described by the tack, the peel resistance and the shear strength (holding power and shear adhesion failure temperature (SAFT)), are difficult to combine in a homogeneous PSA composition. High tack and peel resistance are associated with poor shear strength, and vice versa.
It is an object of the invention to exert a controlled influence over the properties of a radiation-crosslinkable PSA film in such a way as to obtain, overall, an optimum combination of the above-described properties.
We have found that this object is achieved by a method of crosslinking radiation-crosslinkable pressure-sensitive adhesive films by controlled-dose exposure to actinic radiation, which comprises exposing the film surface to a regular or irregular radiation pattern made up of regions of different intensity.
REFERENCES:
patent: 4181752 (1980-01-01), Martens et al.
patent: 4330590 (1982-05-01), Vesley
patent: 5183833 (1993-02-01), Fisher et al.
patent: 5504391 (1996-04-01), Turner et al.
patent: 5891530 (1999-04-01), Wright
patent: 5998096 (1999-12-01), Umemoto et al.
patent: 96/00740 (1996-01-01), None
patent: 97/39837 (1997-10-01), None
patent: 97/400090 (1997-10-01), None
Zhang et al. Modifiaction of polymers with UV excimer radiation from lasers and lamps. J. Adhesion Science and Technology. vol. 8, No. 10 pp. 1179-1210 (1994).*
The American Heritage Dictionary of the English Language, 3rd Ed. (1992).
Brockmann Walter
Geiss Paul Ludwig
Meyer-Roscher Bernd
Schrof Wolfgang
Urban Dieter
BASF - Aktiengesellschaft
Keil & Weinkauf
McClendon Sanza L.
Seidleck James J.
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