The ornamental design for a syntheticresinpaper, as shown and described.
FIG. 1 is a top plan view of a synthetic resin paper;
FIG. 2 is a rear view thereof;
FIG. 3 is a side view thereof; and,
FIG. 4 is an enlarged view of FIG. 1.
The broken lines in the drawings indicate that the synthetic resin paper has no specific length and that the surface pattern repeats uniformly throughout the entire length of the paper. The broken lines form no part of the claimed design.