  We derive new examples for algebraic relations of interacting fields in local
perturbative quantum field theory. The fundamental building blocks in this
approach are time ordered products of free (composed) fields. We give explicit
formulas for the construction of Poincare covariant ones, which were already
known to exist through cohomological arguments.
  For a large class of theories the canonical energy momentum tensor is shown
to be conserved. Classical theories without dimensionful couplings admit an
improved tensor that is additionally traceless. On the example of phi^4-theory
we discuss the improved tensor in the quantum theory. Its trace receives an
anomalous contribution due to its conservation.
  Moreover we define an interacting bilocal normal product for scalar theories.
This leads to an operator product expansion of two time ordered fields.
