Bearings and components thereof comprising a hot-melt pressure sensitive adhesive and methods of their preparation
Methods of making bearings using pressure sensitive macromolecular adhesive polymers and pressure sensitive polymer compositions capable of integrating fluoropolymeric properties with a catechol-amine functionality to form an adhesive system that allows bonding between metallic substrates and fluoropolymers are disclosed. Also disclosed are core-shell polymeric particles comprised of a core and a shell comprising a thermoplastic polydopamine polymer that may be prepared as a colloidal suspension and used as a hot-melt pressure sensitive adhesive capable of binding low surface energy materials, such as polyolefins and fluoropolymers, to diverse materials including metals in making bearings and/or bearing components.
1. A mechanical bearing comprising:
a substrate bonded to a tribological material by an adhesive comprising hot-melt pressure-sensitive core-shell polymeric particles comprising a core and a shell around the core;
wherein the adhesive is comprised of up to about 95% by weight of the hot-melt pressure-sensitive core-shell polymeric particles based on the weight of the adhesive; and
wherein
a. the core is a polymeric particle comprised of one or more polymers or the core is an inorganic particle comprised of one or more non-metallic inorganic materials,
b. the shell comprises a thermoplastic polydopamine polymer comprised of dopamine monomers polymerized to form the polydopamine polymer with one or more carboxylic acids esterified to the polydopamine polymer, and
c. 0 to 100 percent of the shell's thermoplastic polydopamine polymer is grafted onto the core.
2. The bearing of claim 1 , wherein the core comprises the polymeric particle.
3. The bearing of claim 1 , wherein the core comprises polytetrafluoroethylene (PTFE).
4. The bearing of claim 1 , wherein the shell comprises from 2% to 100% of the polydopamine polymer on a dry weight basis.
5. The bearing of claim 1 , wherein at least one of the one or more carboxylic acids esterified to the polydopamine polymer are selected independently from the group consisting of: R1C(O)O— and R1R2CHC(O)O—, where R1 and R2 are each selected independently from the group consisting of —H, phenyl, benzyl; —(CH 2 ) n CH 3 where n is 0-16; amino acids; ethylenically unsaturated carboxylic acids, and vinyl carboxylic acids;
wherein any one or more of the carboxylic acids esterified to the polydopamine polymer may be substituted with one or more functionalities selected from the group consisting of: —F, —Cl, —Br, —OH, carboxy, amino, nitro, methyl, ethyl, and propyl.
6. The bearing of claim 5 , wherein each of the one or more carboxylic acids esterified to the polydopamine polymer is selected independently from the group consisting of: formic, acetic and propanoic acid.
7. The bearing of claim 1 , wherein the adhesive has a resistance-to-peel strength from about 21 to about 80 N as measured by ASTM D6862-11 at 20° C.
8. The bearing of claim 1 , wherein the tribological material is comprised of a fluoropolymer or perfluoropolymer.
9. The bearing of claim 1 , wherein the tribological material is comprised of polytetrafluoroethylene (PTFE).
10. The bearing of claim 1 , wherein the substrate is comprised of a metal or metal alloy.