| 摘要 |
1. A tracer (marking agent) containing a) at least 1 per cent by weight of iron powder and/or powder of a ferromagnetic alloy and at least two of the following groups of substances : b) fluorescent pigments ; c) organic solvent-soluble, water-insoluble fluorescent materials ; d) colorant pigments ; e) sparingly soluble and heat-stable oxides and/or salts of rarer metals ; f) oxides and/or sparingly soluble salts of rare-earth metals ; in microanalytically well detectable amounts in the form of a homogeneous mixture with a thermoplastic material, characterized in that the thermoplastically processable material is a high molecular weight synthetic materials having a low water absorption capacity, a high specific heat capacity, a low thermal conductivity, and a low specific gravity, more specifically a synthetic material selected from the group consisting of polyethylenes, polypropylenes, polyamides, polycarbonates, polyesters, polyoxymethylenes and acrylonitrile-butadiene-styrene copolymers. |
