Photoinitiators and UV-crosslinkable acrylic polymers for pressure sensitive adhesives
View Patent ↗UV-crosslinkable acrylic hotmelt pressure sensitive adhesives comprising acrylic and vinyl monomers, and a polymerizable UV photoinitiator. The photoinitiator comprises a spacer comprising both ethylene oxide and urethane, or urea, carbonate, or siloxane functional groups. The ethylene oxide is directly bonded to the chromophore (e.g., benzophenone) moiety, while the urethane (or urea, carbonate, siloxane) is closely linked to the polymerizable moiety (e.g., styrenic C═C double bond).
1. A photoinitiator having the structural formula
where
Z is S, O, CH 2 , or NH,
R 1-8 are independently H, Cl, Br, I, F, C 1-24 alkoxy, C 1-24 alkyl, or aryl; and wherein at least one of R 1-8 must comprise a —W—X—Y group, where
W is a C 1-12 oxyalkylene,
X comprises tetramethyldisiloxane, and
Y is —R 9 —C(R 10 )═CH 2 , where R 9 is a linear or branched C 2-10 alkylene or C 2-10 oxyalkylene, or arylene or derivative thereof, and R 10 is H or CH 3 .
2. A photoinitiator having the structural formula
where n=1-12.
3. The photoinitiator of claim 2 wherein n=1.
4. A photoinitiator having the structural formula
where n=1-12.
5. The photoinitiator of claim 4 wherein n=1.
6. A photoinitiator having the structural formula
7. A UV curable acrylic polymer comprising the following monomer components:
(a) from about 70 to about 95 parts by weight of acrylic or methacrylic acid derivative of the formula CH 2 ═CH(R 1 )(COOR 2 ), where R 1 is H or CH 3 and R 2 is a C 1-20 alkyl chain,
(b) 0 to about 30 parts by weight of an acrylic or methacrylic acid derivative of the formula CH 2 ═CH(R 1 )(COOR 2 ), where R 1 is H or CH 3 and R 2 is an hydroxyl-functional C 1-20 alkyl chain,
(c) 0 to about 20 parts by weight of an acrylic or vinyl compound containing a carboxy or anhydride functional group,
(d) 0 to about 30 parts by weight of acrylic or vinyl compounds containing an amine, amide, urethane, epoxide or isocyanate functional group and
(e) from about 0.01 to about 15 parts by weight of a photoinitiator having the structural formula
where n=1-12.
8. A UV curable acrylic polymer comprising the following monomer components:
(a) from about 70 to about 95 parts by weight of acrylic or methacrylic acid derivative of the formula CH 2 ═CH(R 1 )(COOR 2 ), where R 1 is H or CH 3 and R 2 is a C 1-20 alkyl chain,
(b) 0 to about 30 parts by weight of an acrylic or methacrylic acid derivative of the formula CH 2 ═CH(R 1 )(COOR 2 ), where R 1 is H or CH 3 and R 2 is an hydroxyl-functional C 1-20 alkyl chain,
(c) 0 to about 20 parts by weight of an acrylic or vinyl compound containing a carboxy or anhydride functional group,
(d) 0 to about 30 parts by weight of acrylic or vinyl compounds containing an amine, amide, urethane, epoxide or isocyanate functional group and
(e) from about 0.01 to about 15 parts by weight of a photoinitiator having the structural formula
where n=1-12.
9. A UV curable acrylic polymer comprising the following monomer components:
(a) from about 70 to about 95 parts by weight of acrylic or methacrylic acid derivative of the formula CH 2 ═CH(R 1 )(COOR 2 ), where R 1 is H or CH 3 and R 2 is a C 1-20 alkyl chain,
(b) 0 to about 30 parts by weight of an acrylic or methacrylic acid derivative of the formula CH 2 ═CH(R 1 )(COOR 2 ), where R 1 is H or CH 3 and R 2 is an hydroxyl-functional C 1-20 alkyl chain,
(c) 0 to about 20 parts by weight of an acrylic or vinyl compound containing a carboxy or anhydride functional group,
(d) 0 to about 30 parts by weight of acrylic or vinyl compounds containing an amine, amide, urethane, epoxide or isocyanate functional group and
(e) from about 0.01 to about 15 parts by weight of a photoinitiator having the structural formula
10. A UV curable hot melt pressure sensitive adhesive comprising
(a) from about 70 to about 95 parts by weight of methyl acrylate, methyl methacrylate, n-butyl acrylate, 2-ethylhexyl acrylate, and/or isooctyl acrylate,
(b) 0 to about 30 parts by weight of hydroxyethyl acrylate and/or hydroxypropyl acrylate,
(c) 0 to about 20 parts by weight of acrylic acid or maleic anhydride,
(d) 0 to about 30 parts by weight of 1 -vinyl-2-pyrrolidinone (NVP), t-octyl acrylamide, 2-(tert-butylamino)ethyl methacrylate (t-BAEM), acrylamide, glycidyl methacrylate, 3-Isopropenyl-α, α-dimethylbenzyl isocyanate (m-TMI®), or a compound of the following formula
and
(e) from about 0.01 to about 15 parts by weight of a photoinitiator selected from the group consisting of
and
where n=1-12.
11. The adhesive of claim 10 wherein component (e) of the acrylic polymer is
where n=1-12.
12. The adhesive of claim 10 wherein component (e) of the acrylic polymer is
where n=1-12.
13. The adhesive of claim 10 , wherein component (e) of the acrylic polymer is