High temperature sterilizable adhesive articles
Sterilization indicators include a first substrate and a second substrate. The first substrate has a compartment containing a fusible indicator material, and a channel in contact with the compartment for the molten indicator material to flow, and a wicking material in contact with the channel. The second substrate has a transparent segment aligned to overlay the wicking material. A high temperature sealing pressure sensitive adhesive layer adheres the first substrate to the second substrate. The adhesive layer includes a (meth)acrylate-based pressure sensitive adhesive matrix and a high temperature sealing agent. The high temperature sealing agent is essentially unreactive at ambient temperature but upon exposure to elevated temperatures forms a heat-sealed adhesive bond.
1 . A sterilization indicator comprising:
a first substrate with a first major surface and a second major surface, wherein the second major surface comprises a compartment containing a fusible indicator material, and a channel in contact with the compartment for a molten indicator material to flow, and a wicking material in contact with the channel;
a second substrate with a first major surface and a second major surface, wherein the second major surface comprises a transparent segment aligned to overlay the wicking material; and
a high temperature sealing pressure sensitive adhesive layer in contact with at least a portion of the second major surface of the first substrate and the first major surface of the second substrate,
wherein the pressure sensitive adhesive layer comprises a (meth) acrylate-based pressure sensitive adhesive matrix and a high temperature sealing agent, the high temperature sealing agent is essentially unreactive with the (meth) acrylate-based pressure sensitive adhesive matrix at ambient temperature and reacts with the (meth) acrylate-based pressure sensitive adhesive matrix at temperatures of at least 121° C. to form a heat-sealed adhesive bond, and the heat-sealed adhesive bond has increased adhesion compared to the bond of the pressure sensitive adhesive layer without the high temperature sealing agent.
2 . The sterilization indicator of claim 1 , wherein the (meth) acrylate-based pressure sensitive adhesive matrix comprises at least one (meth) acrylate copolymer comprising at least one alkyl (meth) acrylate comprising 1-12 carbon atoms, and at least one copolymerizable acid-functional monomer.
3 . The sterilization indicator of claim 2 , wherein the at least one (meth) acrylate copolymer further comprises a crosslinker.
4 . The sterilization indicator of claim 2 , wherein the at least one alkyl (meth) acrylate comprises 4-12 carbon atoms.
5 . The sterilization indicator of claim 1 , wherein the high temperature sealing agent comprises a combination of a thermal free radical generator capable of hydrogen abstraction and an acid-reactive compound.
6 . The sterilization indicator of claim 5 , wherein the thermal free radical generator comprises a peroxide with an activation temperature of at least 100° C.
7 . The sterilization indicator of claim 6 , wherein the thermal free radical generator comprises an alkyl or aryl peroxide.
8 . The sterilization indicator of claim 7 , wherein the thermal free radical generator comprises benzoyl peroxide.
9 . The sterilization indicator of claim 5 , wherein the acid-reactive compound comprises an epoxy-functional compound or a multi-functional compound comprising epoxy-functionality.
10 . The sterilization indicator of claim 5 , wherein the acid-reactive compound comprises an epoxy-functional silane.
11 . The sterilization indicator of claim 10 , wherein the epoxy-functional silane comprises (3-glycidyloxypropyl) trimethoxysilane.
12 . The sterilization indicator of claim 1 , wherein the first substrate comprises a metal foil, and the second substrate comprises a polymeric film.
13 . A method of using a sterilization indicator comprising:
providing a sealable sterilization package;
providing medical instruments to be sterilized;
providing a sterilization indicator of claim 1 ;
sealing the medical instruments and the sterilization indicator in the sterilization package; and
heating the sealed package to sterilize the medical instruments, wherein the indicator comprises;
a first substrate with a first major surface and a second major surface, wherein the second major surface comprises a compartment containing a fusible indicator material, and a channel in contact with the compartment for the molten indicator material to flow, and a wicking material in contact with the channel;
a second substrate with a first major surface and a second major surface, wherein the second major surface comprises a transparent segment aligned to overlay the wicking material; and
a high temperature sealing pressure sensitive adhesive layer in contact with at least a portion of the second major surface of the first substrate and the first major surface of the second substrate,
wherein the pressure sensitive adhesive layer comprises a (meth) acrylate-based pressure sensitive adhesive matrix and a high temperature sealing agent, wherein the high temperature sealing agent is essentially unreactive with the (meth) acrylate-based pressure sensitive adhesive matrix at ambient temperature and reacts with the (meth) acrylate-based pressure sensitive adhesive matrix at temperatures of at least 100° C. to form a heat-sealed adhesive bond, wherein the heat-sealed adhesive bond has increased adhesion compared to the bond of the pressure sensitive adhesive layer without the high temperature sealing agent.
14 . The method of claim 13 , wherein the sterilization indicator passes the ISO 11140-1 (2014) standard.