Improved Adhesion of RF Plasma Treated Rubbers by Isocyanate Incorporation to Polyurethane Adhesive

Abstract

The effect of addition of isocyanate to a polyurethane adhesive has been investigated. Polyurethane adhesive was used for bonding a thermoplastic (TR) and a vulcanized (VR) synthetic butadiene-styrene rubber. CO 2 plasma treatment has oxidized the rubber surfaces, increasing surface energy (wettability), roughness, and favoring mechanical interlocking of rubber surface with the adhesive. Adhesion of TR rubber towards PU polyurethane adhesive was enhanced by these mechanisms; however, migration of antiadherent low molecular weight moieties to the VR rubber/polyurethane adhesive interface produced a lack of adhesion. In this case, it was necessary to produce the crosslinking with isocyanate of the polyurethane adhesive and of the VR rubber surface.

Surface Modification of Surface Wave-Excited Plasma-Treated Chloride-Isobutene Rubber for Adhesion Reduction

“…In general, the oxygen plasma treatment for CIIR rubber produces an important effect in decreasing the contact angle (or increasing the surface free energy) due to an increase in C-O peak and the increase of surface free energy increases adhesive force [21]. Because this chemical interaction produced a remarkable insertion of polar species (oxygen-containing species) increase in surface wettability and adhesive property [2]. However, an opposite trend was observed in this study.…”

“…In order to control the adhesive bonding, plasma treatment has been proposed as one of environmentally friendly surface treatment for rubber [2]. Adhesion between the die and the rubber may be controlled by the surface energies of the materials in contact using the plasma treatment [3].…”

Modification of nitrile‐butadiene rubber surface by immersion into 1,1,2‐trifluoro‐1,2,2‐trichlor‐ethane and its physio‐chemical properties

“…However, prolonged surface etching by sulfuric acid may strongly influence the bulk rubber properties 49 . A surface modification technique widely described in the literature is cold plasma treatment (oxygen or nitrogen plasma) 49–77 . However, plasma treatment affects only the near surface of the rubber, leaving the bulk rubber untreated 49 …”

Improvement of the adhesive capacity of SBR for footwear outsoles by surface activation and coating deposition with atmospheric pressure plasma

“…[ 13 ] Focusing on the improvement of the adhesive capacity of rubber surfaces, plasma treatments have been proved beneficial by removing low molecular weight moieties, inducing roughness, and providing polar species to the surface chemistry. [ 4,14 ] Ortíz‐Magán et al [ 15 ] used oxidizing (air, CO 2 and O 2 ) and nonoxidizing (Ar and N 2 ) low‐pressure plasmas to treat SBR. The plasma treatments produced removal of low molecular weight species by surface ablation as well as oxidation by the creation of C–O, C═O, and RO–C═O moieties.…”

“…This lack of adhesion is due to the nonpolar nature of the rubber and low molecular weight of additives, such as antiozonant paraffin wax and processing oils, which are used in its manufacture, and tend to migrate from the bulk to the rubber surface after vulcanization and generate a weak boundary layer. [ 2–4 ]…”