Exponential convergence for nonlinear SPDEs with double reflecting walls

The present article is devoted to nonlinear stochastic partial differential equations with double reflecting walls driven by possibly degenerate, multiplicative noise. We prove that the corresponding Markov semigroup possesses an exponentially attracting invariant measure through asymptotic coupling, in which Foias-Prodi estimation and the truncation technique are crucial for the realization of the Girsanov transform.