Stable, low cure-temperature semi-structural pressure sensitive adhesive

A method of preparing a post curable pressure sensitive adhesive (PSA) comprising the steps of:

• ( 1) preparing a polymerizable composition consisting essentially of
• (a) at least one free-radically polymerizable monomer,
• (b) at least one thermal free-radical initiator,
• (c) at least one cationically-polymerizable monomer,
• (d) a photoactivatable catalyst system for the cationically-polymerizable monomer comprising at least one organometallic complex salt or at least one onium salt, and
• (e) optionally, a monohydric or polyhydric alcohol;
• and
• (2) applying sufficient thermal energy to the mixture to effect essentially complete polymerization of the free-radically polymerizable monomer;
• and wherein there is essentially no conversion of the cationically-polymerizable monomer component of the curable pressure sensitive adhesive for at least 10 days at 20.degree. C., 50% relative humidity, when the curable pressure sensitive adhesive is stored in a manner to exclude actinic radiation.

A method for preparing a curable pressure sensitive adhesive (PSA) comprising the steps:

• (1) preparing a first polymerizable composition consisting essentially of a mixture of
• (a) at least one free-radically polymerizable monomer,
• (b) at least one free-radical initiator,
• (c) at least one cationically-polymerizable monomer, and
• (d) optionally, a monohydric or polyhydric alcohol;
• (2) applying sufficient energy to the mixture to effect essentially complete polymerization of the free-radically polymerizable monomer;
• (3) mixing into the polymerized composition,
• (a) a photoinitiated catalyst system for the cationically-polymerizable monomer comprising at least one organometallic complex salt or at least one onium salt, and
• (b) optionally, a monohydric or polyhydric alcohol;
• and wherein there is essentially no conversion of the cationically-polymerizable monomer component of the curable pressure sensitive adhesive for at least 10 days at 20.degree. C., 50% relative humidity, when the curable pressure sensitive adhesive is stored in a manner to exclude actinic radiation.

A method for preparing a curable pressure sensitive adhesive (PSA) comprising the steps:

• (1) preparing a first polymerizable composition consisting essentially of a mixture of
• (a) at least one free-radically polymerizable monomer, and
• (b) at least one free-radical initiator;
• and
• (2) applying sufficient energy to the mixture to effect essentially complete polymerization of the free-radically polymerizable monomer;
• (3) mixing into the polymerized composition, a second polymerizable composition comprising a mixture of:
• (a) at least one cationically-polymerizable monomer,
• (b) a photoinitiated catalyst system for the cationically-polymerizable monomer comprising at least one organometallic complex salt or at least one onium salt, and
• (c) optionally, a monohydric or polyhydric alcohol;
• and wherein there is essentially no conversion of the cationically-polymerizable monomer component of the curable pressure sensitive adhesive for at least 10 days at 20.degree. C., 50% relative humidity, when the curable pressure sensitive adhesive is stored in a manner to exclude actinic radiation.