Example 3
The composition of Example 3 is a high performance PSA with moisture curable oligomer (Cure In Place Adhesive), In order to incorporate the in-situ moisture cure into a high performance pressure sensitive adhesive system, an acrylic polymer, tackifer, and reactive oligomer are admixed or otherwise combined in solvent. This system is coated into tape form under conditions which leaves a portion of the oligomer latent to react after application and exposure to humidity.
TABLE 3
Formulation of Example 3 PSA
Weight PercentComponent
54.45%DEV-8631U (acrylic base polymer)
25%Terpene phenolic tackifier (softening point 110-120° C.)
20%Terpene phenolic tackifier (softening point 110-120° C.)
0.55%Metal chelate aluminum acetyl acetonate (crosslinker
&catalyst)
The acrylic base polymer is a high molecular weight (400-600 k g/mol) random copolymer including (a) an alkyl acrylate base monomer; (b) vinyl acetate; (c) methyl acrylate; (d) acrylic acid; and (e) a silane crosslinking monomer.
An example of the acrylic base polymer is DEV8631U, which is a random copolymer having a molecular weight (Mw) of about 518,000 g/mol, which includes the following constituents.
TABLE 4
Acrylic Base Polymer (i.e., DEV8631U) in Example 3 PSA
ComponentWeight Percent
2-Ethylhexyl acrylate (base monomer)57.95
Vinyl acetate (modifying monomer)25
Methyl acrylate15
Acrylic acid (high Tg monomer, crosslinking site)3
methacroyloxypropyltrimetoxy silane 0.05
(crosslinking monomer)
The reactive oligomer is a silane-terminated polyether (an oligomer) such as STPE-30 from Wacker as shown below as formula (22). STPE-30 is a silane terminated polyether. The two silane-terminated polypropylene glycols shown are based on the same polyether. The difference is in the end group.
[Figure (not displayed)]
The crosslinker and catalyst is aluminum acetylacetonate and is shown below as formula (23):
[Figure (not displayed)]
The adhesive bonding process is depicted in FIG. 6. Referring to FIG. 6, generally, a bonding process 200 in accordance with the present subject matter is as follows. In operation 210, a composition as described herein is coated or otherwise applied onto a film or substrate. An example of such a film is a release film. After appropriate application, the composition is dried which typically also includes removal of at least a portion of any solvent in the composition, as depicted as operation 220. Representative conditions for drying include exposure to 80° C. for about 5 minutes. In operation 230, the composition is then cured in place by exposure to heat and/or humidity, to thereby form a high strength adhesive, 240. The condensation reaction taking place is shown below:
˜Si—OCH3+H2O→˜Si—O—Si˜+CH3OH
FIG. 1 depicts a dynamic mechanical analysis of the cure in place pressure sensitive adhesive of Example 3.
