Silicone-based pressure-sensitive adhesive
Silicone-based pressure-sensitive adhesives, reaction mixtures used to form the pressure-sensitive adhesives, methods of making the silicone-based pressure-sensitive adhesives, and articles containing the silicone-based pressure-sensitive adhesives are described. More particularly, the silicone-based pressure-sensitive adhesives include silicone-based elastomeric materials that are prepared by polymerizing a silicone compound having at least two ethylenically unsaturated groups in the presence of actinic radiation (e.g., ultraviolet radiation) and a controlled radical initiator. The controlled radical initiator is a bis-dithiocarbamate or bis-dithiocarbonate compound having a single carbon between the two dithiocarbamate or dithiocarbonate groups.
1. A silicone-based pressure-sensitive adhesive composition comprising a polymerized product of a reaction mixture comprising:
a) a silicone compound having at least two ethylenically unsaturated groups, the silicone compound being of Formula (I)
wherein
Q 1 is a polydiorganosiloxane group;
each Y 1 is an alkylene, arylene, aralkylene, or a combination thereof;
each R 2 is a hydrogen or methyl;
each R 3 is a single bond or is a divalent group that is a carbonyl, carbonylimino, carbonyloxy, imino, oxy, alkylene, alkylene substituted with a hydroxyl group, aralkylene, or a combination thereof; and
each R 4 is hydrogen or an alkyl;
b) a photoinitiator of Formula (II)
wherein
each R 10 is an alkoxy, aryloxy, alkaryloxy, aralkyloxy, alkenoxy, or N(R 13 ) 2 ;
R 11 is a group of formula (OR 14 ) p —OR 15 or a group of formula —(CO)A-R 16 ;
R 12 is a hydrogen, alkyl, aryl, aralkyl, alkaryl, a group of formula —(CO)OR 17 , or a group of formula —(CO)N(R 18 ) 2 ;
each R 13 is an alkyl or two adjacent R 13 are combined with the nitrogen to which they are both attached to form a first heterocyclic ring having 1 to 3 heteroatoms selected from nitrogen, oxygen, and sulfur, the first heterocyclic ring being saturated or unsaturated and optionally fused to one or more second rings that are carbocyclic or heterocyclic;
each R 14 is an alkylene;
R 15 is an alkyl;
R 16 is hydrogen, alkyl, aryl, aralkyl, or alkaryl;
R 17 is an alkyl, aryl, aralkyl, or alkaryl;
each R 18 is an alkyl, aryl, aralkyl, or alkaryl;
X is oxy or —NR 19 —;
R 19 is hydrogen, alkyl, aryl, aralkyl, or alkaryl; and
p is an integer equal to at least 0; and
c) a silicone tackifying resin.
2. The silicone-based pressure-sensitive adhesive composition of claim 1 , wherein the photoinitiator of Formula (II) is of Formula (II-1A) or Formula (II-1B)
wherein
each R 20 is an alkyl, aryl, alkaryl, aralkyl, or alkenyl;
R 15 is an alkyl;
R 16 is hydrogen, alkyl, aryl, aralkyl, or alkaryl;
X is oxy or —NR 19 —; and
R 19 is hydrogen, alkyl, aryl, aralkyl, or alkaryl.
3. The silicone-based pressure-sensitive adhesive composition of claim 2 , wherein the photoinitator is of Formula (II-1A) and R 20 is an alkyl.
4. The silicone-based pressure-sensitive adhesive composition of claim 2 , wherein the photoinitiator is of Formula (II-1B), R 20 is alkyl, R 16 is alkyl, X is oxy.
5. The silicone-based pressure-sensitive adhesive composition of claim 1 , wherein the photoinitiator of Formula (II) is of Formula (II-2A) or Formula (II-2B)
wherein
each R 13 is an alkyl or two adjacent R 13 groups are combined with the nitrogen to which they are both attached to form a first heterocyclic ring having 1 to 3 heteroatoms selected from nitrogen, oxygen, and sulfur, the first heterocyclic ring being saturated or unsaturated and optionally fused to one or more second rings that are carbocyclic or heterocyclic;
R 15 is an alkyl;
R 16 is hydrogen, alkyl, aryl, aralkyl, or alkaryl;
X is oxy or —NR 19 —; and
R 19 is hydrogen, alkyl, aryl, aralkyl, or alkaryl.
6. The silicone-based pressure-sensitive adhesive composition of claim 5 , wherein the photoinitiator is of Formula (II-2A) and each R 13 is an alkyl.
7. The silicone-based pressure-sensitive adhesive composition of claim 5 , wherein the photoinitiator is of Formula (II-2B), each R 13 is alkyl, X is oxy, and R 16 is alkyl.
8. The silicone-based pressure-sensitive adhesive composition of claim 1 , wherein the reaction mixture further comprises a silicone compound having a single ethylenically unsaturated group.
9. The silicone-based pressure-sensitive adhesive composition of claim 1 , wherein the reaction mixtures comprise 30 to 80 weight percent of the silicone compound of Formula (I), 0.001 to 5 weight percent of the photoinitiator of Formula (II), and 20 to 65 weight percent silicone tackifying resin.
10. The silicone-based pressure-sensitive adhesive composition of claim 1 , wherein the reaction mixture optionally further comprises 0 to 25 weight percent of a silicone compound of Formula (I) and/or 0 to 20 weight percent of a filler based on the total weight of solids in the reaction mixture.
11. The silicone-based pressure-sensitive adhesive composition of claim 1 , wherein the polymerized product comprises a mixture of a silicone-based elastomeric material and the silicone tackifying resin.
12. An article comprising a silicone-based pressure-sensitive adhesive composition of claim 1 and a substrate, wherein the silicone-based pressure-sensitive adhesive is positioned adjacent to the substrate.
13. A method of making a silicone-based pressure-sensitive adhesive comprising a silicone-based elastomeric material and a silicone tackifying resin, the method comprising:
forming reaction mixture comprising
a) a silicone compound having at least two ethylenically unsaturated groups, the silicone compound being of Formula (I)
wherein
Q 1 is a polydiorganosiloxane group;
each Y 1 is an alkylene, arylene, aralkylene, or a combination thereof;
each R 2 is a hydrogen or methyl;
each R 3 is a single bond or is a divalent group that is a carbonyl, carbonylimino, carbonyloxy, imino, oxy, alkylene, alkylene substituted with a hydroxyl group, aralkylene, or a combination thereof, and
each R 4 is hydrogen or an alkyl;
b) a photoinitiator of Formula (II)
wherein
each R 10 is an alkoxy, aryloxy, alkaryloxy, aralkyloxy, alkenoxy, or —N(R 13 ) 2 ;
R 11 is a group of formula —(OR 14 ) p —OR 15 or a group of formula —(CO)—X—R 16 ;
R 12 is a hydrogen, alkyl, aryl, aralkyl, alkaryl, a group of formula —(Co)OR 17 , or a group of formula —(CO)N(R 18 ) 2 ;
each R 13 is an alkyl or two adjacent R 13 groups are combined with the nitrogen to which they are both attached to form a first heterocyclic ring having 1 to 3 heteroatoms selected from nitrogen, oxygen, and sulfur, the first heterocyclic ring being saturated or unsaturated and optionally fused to one or more second rings that are carbocyclic or heterocyclic;
each R 14 is an alkylene;
R 15 is an alkyl;
R 16 is hydrogen, alkyl, aryl, aralkyl, or alkaryl;
R 17 is an alkyl, aryl, aralkyl, or alkaryl;
each R 18 is an alkyl, aryl, aralkyl, or alkaryl;
X is oxy or —NR 19 —;
R 19 is hydrogen, alkyl, aryl, aralkyl, or alkaryl; and
p is an integer equal to at least 0; and
c) a silicone tackifying resin; and
exposing the reaction mixture to actinic radiation to form the silicon-based elastomeric material.
14. The method of claim 12 , wherein the actinic radiation is ultraviolet radiation.