US-12624257-B2 - Adhesive primer for flexographic plate mounting tape

US12624257B2US 12624257 B2US12624257 B2US 12624257B2US-12624257-B2

Abstract

Primer layers for adhesion of a pressure sensitive adhesive material to a substrate are provided. The primer layer comprises a crosslinked polymer. In some embodiments, the primer layer has an atomic nitrogen content of greater than 6 wt %, and in some a ratio of atomic weight percent of oxygen to nitrogen of less than 3.0. In some embodiments the crosslinked polymer is the reaction product of an amine-functional base polymer such as a polyethylenimine (PEI) and a crosslinker, which may be a polyaziridine crosslinker. Also provided are two-layer constructions comprising the primer layer and a substrate layer; and tapes, such as flexographic plate mounting tapes, comprising the two-layer construction and a pressure sensitive adhesive layer.

Inventors

Becky A. Jetto
David T. Amos
Jeffrey A. Peterson
Scott A. Van Wert

Assignees

3M INNOVATIVE PROPERTIES COMPANY

Dates

Publication Date: 20260512
Application Date: 20181101

Claims (20)

1 . A primer layer for adhesion of a pressure sensitive adhesive material to a substrate, the primer layer comprising a crosslinked polymer which is the reaction product of an amine-functional base polymer and a polyaziridine crosslinker, wherein the amine-functional base polymer is a branched polyethylenimine.
2 . The primer layer according to claim 1 , wherein the polyaziridine crosslinker is pentaerythritol tris (3-(1-aziridinyl) propionate).
3 . A two-layer construction comprising the primer layer according to claim 1 immediately adjacent to and directly bound to a substrate layer.
4 . The two-layer construction according to claim 3 wherein the substrate layer comprises one or more materials selected from the group consisting of polyester polymers, polypropylene polymers, and polycarbonate polymers.
5 . The two-layer construction according to claim 3 wherein the substrate layer comprises one or more polyester polymers.
6 . A tape comprising the two-layer construction according to claim 3 and a first pressure sensitive adhesive layer comprising a pressure sensitive adhesive material, wherein the pressure sensitive adhesive layer is immediately adjacent to and directly bound to the primer layer.
7 . The tape according to claim 6 which is a flexographic plate mounting tape for adhering a flexographic printing plate to a plate cylinder in a flexographic printing press.
8 . The tape according to claim 6 wherein the pressure sensitive adhesive material comprises a polyacrylate polymer comprising acidic polar monomer units.
9 . The tape according to claim 6 additionally comprising a second pressure sensitive adhesive layer borne on a face of the tape opposite the first pressure sensitive adhesive layer.
10 . The tape according to claim 6 adhered to a flexographic printing plate and a plate cylinder of a flexographic printing press.
11 . A method of making a two-layer construction according to claim 3 , the method comprising the steps of: a) providing the substrate layer; and b) coating the substrate layer with a coating mixture comprising the amine-functional base polymer and the polyaziridine crosslinker.
12 . The method according to claim 11 additionally comprising the step of: c) reacting the polyaziridine crosslinker with the amine-functional base polymer so as to generate a primer layer comprising the crosslinked polymer.
13 . The method according to claim 12 wherein step c) additionally comprises reacting the polyaziridine crosslinker with the substrate layer so as to form covalent bonds between the substrate layer and the primer layer.
14 . The method according to claim 11 additionally comprising the step of: d) stretching the substrate layer; where step d) is carried out after step b).
15 . A tape comprising a primer layer comprising a crosslinked polymer, which is the reaction product of a branched polyethylenimine and pentaerythritol tris (3-(1-aziridinyl) propionate), immediately adjacent to and directly bound to a substrate layer and a first pressure sensitive adhesive layer comprising a pressure sensitive adhesive material, wherein the pressure sensitive adhesive layer is immediately adjacent to and directly bound to the primer layer.
16 . The tape according to claim 15 wherein the pressure sensitive adhesive material comprises a polyacrylate polymer comprising acrylic acid monomer units.
17 . The tape according to claim 15 , further comprising a second primer layer immediately adjacent to and directly bound to the substrate layer on a face opposite the first primer layer.
18 . The tape according to claim 17 , wherein the second primer layer comprises the crosslinked polymer which is the reaction product of a branched polyethylenimine and pentaerythritol tris (3-(1-aziridinyl) propionate).
19 . The tape according to claim 17 , wherein the primer layer and the second primer layer differ in composition.
20 . The tape according to claim 17 , further comprising a second pressure sensitive adhesive layer, wherein the second pressure sensitive adhesive layer is immediately adjacent to and directly bound to the second primer layer.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application is a national stage filing under 35 U.S.C. 371 of PCT/IB2018/058581, filed Nov. 1, 2018, which claims the benefit of U.S. Provisional Application No. 62/582,978, filed Nov. 8, 2017, the disclosure of which is incorporated by reference in its/their entirety herein. FIELD OF THE DISCLOSURE This disclosure relates to primers for bonding pressure sensitive adhesive (PSA) to a reinforcing film, such as may be used in a flexographic plate mounting tape, as well as flexographic plate mounting tapes incorporating this primer and methods of making and using such tapes. BACKGROUND OF THE DISCLOSURE Flexographic plate mounting tapes are used to mount flexographic printing plates to plate cylinders in a flexographic printing press. The following references may be relevant to the general field of technology of the present disclosure: U.S. 2006/0145127; U.S. Pat. Nos. 5,156,904; 6,915,741; 8,962,777; U.S. 2015/0361307; U.S. Pat. Nos. 8,152,944; 8,802,226; U.S. 2011/0019280. U.S. Pat. No. 5,156,904 is titled “Polymeric Film Coated In-Line with Polyethyleneimine”. A search of this document reveals that the terms “polyaziridine” and “polyaziridine crosslinker” do not appear in this reference, nor does the reference use the term “crosslink” in connection with polyethyleneimine. SUMMARY OF THE DISCLOSURE Briefly, the present disclosure provides primer layers for adhesion of a pressure sensitive adhesive material to a substrate, where the primer layer comprises a crosslinked polymer. In some embodiments, the primer layer has an atomic nitrogen content of greater than 6 wt %, greater than 8 wt %, greater than 10 wt %, greater than 12 wt %, greater than 14 wt %, or in some embodiments greater than 16 wt %. In some embodiments, the primer layer has a ratio of atomic weight percent of oxygen to nitrogen of less than 3.0, less than 2.5, less than 2.0, or in some embodiments less than 1.5. In some embodiments the crosslinked polymer comprises at least 50 wt % of the total weight of the primer layer, at least 60 wt %, at least 70 wt %, or in some embodiments at least 80 wt % of the total weight of the primer layer. In some embodiments the crosslinked polymer is the reaction product of a base polymer and a crosslinker or the reaction product of an amine-functional base polymer and a crosslinker. In some embodiments the crosslinker is a polyaziridine crosslinker. In some embodiments the polyaziridine crosslinker comprises two or more aziridine groups, in others three or more aziridine groups. In some embodiments the polyaziridine crosslinker is pentaerythritol tris (3-(1-aziridinyl) propionate). In some embodiments the amine-functional base polymer is a polyethylenimine (PEI). In some embodiments the primer layer additionally comprises inorganic filler which may be silica or fumed silica. Additional embodiments of the primer layers of the present disclosure are described below under “Selected Embodiments.” In another aspect, the present disclosure provides two-layer constructions comprising the primer layer according to the present disclosure and a substrate layer. In some embodiments, the substrate layer may comprise polyester polymers, polypropylene polymers, and/or polycarbonate polymers. In some embodiments the substrate layer comprises an oriented film. In some embodiments the two-layer construction is in the of a roll, optionally rolled upon itself without a liner. Additional embodiments of the two-layer constructions of the present disclosure are described below under “Selected Embodiments.” In another aspect, the present disclosure provides a tape, which may be a flexographic plate mounting tape, comprising the two-layer construction according to the present disclosure and a first pressure sensitive adhesive layer comprising a pressure sensitive adhesive material. In some embodiments, the pressure sensitive adhesive material comprises polyacrylate polymer, optionally comprising acidic polar monomer units, optionally monomer units derived from acrylic acid. In some embodiments the tape comprises a second pressure sensitive adhesive layer borne on a face of the tape opposite the first pressure sensitive adhesive layer. In some embodiments the tape comprises a foam layer. Additional embodiments of the tapes of the present disclosure are described below under “Selected Embodiments.” In another aspect, the present disclosure provides the use of the tape according to the present disclosure to adhere a flexographic printing plate to a plate cylinder of a flexographic printing press. Further, the present disclosure provides methods of mounting flexographic printing plates to plate cylinders in a flexographic printing press. Additional embodiments of methods of use of the present disclosure are described below under “Selected Embodiments.” In another aspect, the present disclosure provides methods of making two-layer constructions according to the present disclosure comprising the