Heat-activatable siloxane-based adhesives

A heat-activatable transfer tape comprising:

• an optically transparent heat-activatable adhesive layer with a first major surface and a second major surface, the optically transparent heat-activatable adhesive layer comprising:
• a siloxane-based elastomeric polymer comprises a segmented copolymer of Formula 1 or Formula 2:
• wherein each R is a moiety that, independently, is an alkyl moiety, having about 1 to 12 carbon atoms, and may be substituted with, for example, trifluoroalkyl or vinyl groups, a vinyl radical or a higher alkenyl radical, a cycloalkyl moiety having from about 6 to 12 carbon atoms and may be substituted with alkyl, fluoroalkyl, and vinyl groups, or an aryl moiety having from about 6 to 20 carbon atoms and may be substituted;
• each Z is a polyvalent radical that is an arylene radical or an aralkylene radical having from about 6 to 20 carbon atoms, an alkylene or cycloalkylene radical having from about 6 to 20 carbon atoms;
• each Y is a polyvalent radical that independently is an alkylene radical of 1 to 10 carbon atoms, an aralkylene radical or an arylene radical having 6 to 20 carbon atoms;
• each D is selected from the group consisting of hydrogen, an alkyl radical of 1 to 10 carbon atoms, phenyl, and a radical that completes a ring structure including B or Y to form a heterocycle;
• where B is a polyvalent radical selected from the group consisting of alkylene, aralkylene, cycloalkylene, phenylene, heteroalkylene, and copolymers and mixtures thereof;
• m is a number that is 0 to about 1000;
• n is a number that is at least 1;
• and
• p is a number that is at least 10, in some embodiments 15 to about 2000, or even 30 to 1500;
• wherein each R1 is independently an alkyl, haloalkyl, aralkyl, alkenyl, aryl, or aryl substituted with an alkyl, alkoxy, or halo;
• each Y is independently an alkylene, aralkylene, or a combination thereof;
• subscript a is independently an integer of 40 to 1500;
• subscript b is an integer of 1 to 10;
• G is a divalent group that is the residue unit that is equal to a diamine of formula R3HN-G-NHR3 minus the two —NHR3 groups;
• each R3 is hydrogen or an alkyl having 1 to 10 carbon atoms, or R3 taken together with G and with the nitrogen to which they are both attached forms a heterocyclic group;
• each asterisk (*) indicates a site of attachment of the repeat unit to another group in the copolymer;
• and
• wherein the heat-activatable adhesive is non-tacky and non-adhesive to substrates at a temperature of less than 50° C. and is adhesive to substrates at a temperature of greater than 50° C. up to a temperature of 10° C. below the decomposition temperature of the siloxane-based elastomeric polymer;
• and wherein at least one of the first major surface or the second major surface comprises a microstructured pattern on the surface such that the microstructured pattern is a permanent feature of the adhesive surface, and wherein the microstructured surface alters the direction of light.

A method of preparing an adhesive article comprising:

• providing a first substrate with a first surface and a second surface;
• providing a heat-activatable adhesive, wherein the heat-activatable adhesive comprises:
• a hot melt processable siloxane-based elastomeric polymer, wherein the siloxane-based elastomeric polymer comprises a segmented copolymer of Formula 1 or Formula 2:
• wherein each R is a moiety that, independently, is an alkyl moiety, having about 1 to 12 carbon atoms, and may be substituted with, for example, trifluoroalkyl or vinyl groups, a vinyl radical or a higher alkenyl radical, a cycloalkyl moiety having from about 6 to 12 carbon atoms and may be substituted with alkyl, fluoroalkyl, and vinyl groups, or an aryl moiety having from about 6 to 20 carbon atoms and may be substituted;
• each Z is a polyvalent radical that is an arylene radical or an aralkylene radical having from about 6 to 20 carbon atoms, an alkylene or cycloalkylene radical having from about 6 to 20 carbon atoms;
• each Y is a polyvalent radical that independently is an alkylene radical of 1 to 10 carbon atoms, an aralkylene radical or an arylene radical having 6 to 20 carbon atoms;
• each D is selected from the group consisting of hydrogen, an alkyl radical of 1 to 10 carbon atoms, phenyl, and a radical that completes a ring structure including B or Y to form a heterocycle;
• where B is a polyvalent radical selected from the group consisting of alkylene, aralkylene, cycloalkylene, phenylene, heteroalkylene, and copolymers and mixtures thereof;
• m is a number that is 0 to about 1000;
• n is a number that is at least 1;
• and
• p is a number that is at least 10, in some embodiments 15 to about 2000, or even 30 to 1500;
• wherein each R1 is independently an alkyl, haloalkyl, aralkyl, alkenyl, aryl, or aryl substituted with an alkyl, alkoxy, or halo;
• each Y is independently an alkylene, aralkylene, or a combination thereof;
• subscript a is independently an integer of 40 to 1500;
• subscript b is an integer of 1 to 10;
• G is a divalent group that is the residue unit that is equal to a diamine of formula R3HN-G-NHR3 minus the two —NHR3 groups;
• each R3 is hydrogen or an alkyl having 1 to 10 carbon atoms, or R3 taken together with G and with the nitrogen to which they are both attached forms a heterocyclic group;
• each asterisk (*) indicates a site of attachment of the repeat unit to another group in the copolymer;
• and
• wherein the heat-activatable adhesive is non-tacky and non-adhesive to substrates at a temperature of less than 50° C. and is adhesive to substrates at a temperature of greater than 50° C. up to a temperature of 10° C. below the decomposition temperature of the siloxane-based elastomeric polymer;
• heating the heat-activatable adhesive to a temperature of greater than 50° C. up to a temperature of 10° C. below the decomposition temperature of the siloxane-based elastomeric polymer;
• applying the heat-activatable adhesive to at least a portion of the surface of the first substrate;
• and
• cooling the heat-activatable adhesive to room temperature.